diff --git a/.gitattributes b/.gitattributes
index 446c698e..49f1e1b6 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -14,6 +14,7 @@
 /phpcs.xml.dist export-ignore
 /phpunit.xml export-ignore
 /phpunit.xml.dist export-ignore
+/.github export-ignore
 /Yoast/Tests export-ignore
 
 #
@@ -27,3 +28,4 @@
 #
 *.md text
 *.php text
+*.inc text
diff --git a/.phpcs.xml.dist b/.phpcs.xml.dist
index 17542c91..c7bde9e4 100644
--- a/.phpcs.xml.dist
+++ b/.phpcs.xml.dist
@@ -5,6 +5,13 @@
 
 	<description>The Coding standard for the YoastCS Coding Standard itself.</description>
 
+	<!--
+	#############################################################################
+	COMMAND LINE ARGUMENTS
+	https://github.com/squizlabs/PHP_CodeSniffer/wiki/Annotated-ruleset.xml
+	#############################################################################
+	-->
+
 	<!-- Scan all files. -->
 	<file>.</file>
 
@@ -14,6 +21,19 @@
 	<!-- Show progress, show the error codes for each message (source). -->
 	<arg value="sp"/>
 
+	<!-- Strip the filepaths down to the relevant bit. -->
+	<arg name="basepath" value="./"/>
+
+	<!-- Check up to 8 files simultaneously. -->
+	<arg name="parallel" value="8"/>
+
+
+	<!--
+	#############################################################################
+	USE THE YoastCS RULESET
+	#############################################################################
+	-->
+
 	<!-- YoastCS supports PHP 5.4 or higher. -->
 	<config name="testVersion" value="5.4-"/>
 
@@ -32,11 +52,19 @@
 	<!-- Enforce PSR1 compatible namespaces. -->
 	<rule ref="PSR1.Classes.ClassDeclaration"/>
 
+
+	<!--
+	#############################################################################
+	SNIFF SPECIFIC CONFIGURATION
+	#############################################################################
+	-->
+
 	<rule ref="Yoast.NamingConventions.NamespaceName">
 		<properties>
 			<property name="prefixes" type="array">
 				<element value="YoastCS\Yoast"/>
 			</property>
+			<property name="src_directory" value="Yoast"/>
 		</properties>
 	</rule>
 
diff --git a/.travis.yml b/.travis.yml
index 0f080913..e3870a0e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,7 +18,7 @@ php:
     - 7.1
     - 7.2
     - 7.3
-    - "7.4snapshot"
+    - 7.4
 
 env:
   # Test against the highest/lowest supported PHPCS and WPCS versions.
@@ -67,9 +67,9 @@ matrix:
     # This is a much quicker test which only runs the unit tests and linting against low/high
     # supported PHP/PHPCS/WPCS combinations.
     - stage: quicktest
-      php: 7.3
+      php: 7.4
       env: PHPCS_BRANCH="dev-master" WPCS="dev-develop" PHPLINT=1
-    - php: 7.3
+    - php: 7.4
       env: PHPCS_BRANCH="3.5.0" WPCS="2.2.0"
     - php: 5.4
       env: PHPCS_BRANCH="dev-master" WPCS="2.2.0" PHPLINT=1
diff --git a/CHANGELOG.md b/CHANGELOG.md
index bdb49937..b9298fd0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,17 @@ All notable changes to this project will be documented in this file.
 
 This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a CHANGELOG](https://keepachangelog.com/).
 
+### [2.0.1] - 2020-02-06
+
+#### Changed
+* Composer: Supported version of the [DealerDirect Composer PHPCS plugin] has been changed from `^0.5.0` to `^0.5 || ^0.6`.
+    Note: this requirement is flexible to prevent conflicts with included standards which may include the plugin as well.
+* Various housekeeping.
+
+#### Fixed
+* `Yoast.NamingConventions.NamespaceName`: fixed a potential "undefined index" notice.
+
+
 ### [2.0.0] - 2019-12-17
 
 #### Added
@@ -358,6 +369,7 @@ Initial public release as a stand-alone package.
 [DealerDirect Composer PHPCS plugin]: https://github.com/Dealerdirect/phpcodesniffer-composer-installer/releases
 [Parallel-Lint]: https://packagist.org/packages/jakub-onderka/php-parallel-lint
 
+[2.0.1]: https://github.com/Yoast/yoastcs/compare/2.0.0...2.0.1
 [2.0.0]: https://github.com/Yoast/yoastcs/compare/1.3.0...2.0.0
 [1.3.0]: https://github.com/Yoast/yoastcs/compare/1.2.2...1.3.0
 [1.2.2]: https://github.com/Yoast/yoastcs/compare/1.2.1...1.2.2
diff --git a/README.md b/README.md
index b52c57ab..74bc766a 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ Composer will automatically install dependencies, register standards paths, and
 To include standards as part of a project require them as development dependencies:
 
 ```bash
-composer require --dev yoast/yoastcs:^1.0
+composer require --dev yoast/yoastcs:^2.0
 ```
 
 Composer will automatically install dependencies and register the YoastCS and other external standards with PHP_CodeSniffer.
diff --git a/Yoast/Sniffs/Commenting/CodeCoverageIgnoreDeprecatedSniff.php b/Yoast/Sniffs/Commenting/CodeCoverageIgnoreDeprecatedSniff.php
index 7da47be2..8bd93e9d 100644
--- a/Yoast/Sniffs/Commenting/CodeCoverageIgnoreDeprecatedSniff.php
+++ b/Yoast/Sniffs/Commenting/CodeCoverageIgnoreDeprecatedSniff.php
@@ -20,11 +20,11 @@ class CodeCoverageIgnoreDeprecatedSniff implements Sniff {
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
-	 * @return array
+	 * @return (int|string)[]
 	 */
 	public function register() {
 		return [
-			T_FUNCTION,
+			\T_FUNCTION,
 		];
 	}
 
@@ -41,14 +41,14 @@ public function process( File $phpcsFile, $stackPtr ) {
 
 		$tokens = $phpcsFile->getTokens();
 		$find   = Tokens::$methodPrefixes;
-		$find[] = T_WHITESPACE;
+		$find[] = \T_WHITESPACE;
 
 		$commentEnd = $stackPtr;
 		do {
 			$commentEnd = $phpcsFile->findPrevious( $find, ( $commentEnd - 1 ), null, true );
 		} while ( $tokens[ $commentEnd ]['line'] === $tokens[ $stackPtr ]['line'] );
 
-		if ( $tokens[ $commentEnd ]['code'] !== T_DOC_COMMENT_CLOSE_TAG
+		if ( $tokens[ $commentEnd ]['code'] !== \T_DOC_COMMENT_CLOSE_TAG
 			|| $tokens[ $commentEnd ]['line'] !== ( $tokens[ $stackPtr ]['line'] - 1 )
 		) {
 			// Function without (proper) docblock. Not our concern.
@@ -83,10 +83,10 @@ public function process( File $phpcsFile, $stackPtr ) {
 			return;
 		}
 
-		$hasTagAsString = $phpcsFile->findNext( T_DOC_COMMENT_STRING, ( $commentStart + 1 ), $commentEnd, false, 'codeCoverageIgnore' );
+		$hasTagAsString = $phpcsFile->findNext( \T_DOC_COMMENT_STRING, ( $commentStart + 1 ), $commentEnd, false, 'codeCoverageIgnore' );
 		if ( $hasTagAsString !== false ) {
-			$prev = $phpcsFile->findPrevious( T_DOC_COMMENT_WHITESPACE, ( $hasTagAsString - 1 ), $commentStart, true );
-			if ( $prev !== false && $tokens[ $prev ]['code'] === T_DOC_COMMENT_STAR ) {
+			$prev = $phpcsFile->findPrevious( \T_DOC_COMMENT_WHITESPACE, ( $hasTagAsString - 1 ), $commentStart, true );
+			if ( $prev !== false && $tokens[ $prev ]['code'] === \T_DOC_COMMENT_STAR ) {
 				$fix = $phpcsFile->addFixableError(
 					'The `codeCoverageIgnore` annotation in the function docblock needs to be prefixed with an `@`.',
 					$hasTagAsString,
diff --git a/Yoast/Sniffs/Commenting/CoversTagSniff.php b/Yoast/Sniffs/Commenting/CoversTagSniff.php
index 173ca4b0..0fa8158d 100644
--- a/Yoast/Sniffs/Commenting/CoversTagSniff.php
+++ b/Yoast/Sniffs/Commenting/CoversTagSniff.php
@@ -42,11 +42,11 @@ class CoversTagSniff implements Sniff {
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
-	 * @return array
+	 * @return (int|string)[]
 	 */
 	public function register() {
 		return [
-			T_DOC_COMMENT_OPEN_TAG,
+			\T_DOC_COMMENT_OPEN_TAG,
 		];
 	}
 
@@ -80,8 +80,8 @@ public function process( File $phpcsFile, $stackPtr ) {
 			}
 
 			// Found a @covers tag.
-			$next = $phpcsFile->findNext( T_DOC_COMMENT_WHITESPACE, ( $tag + 1 ), null, true );
-			if ( $tokens[ $next ]['code'] !== T_DOC_COMMENT_STRING
+			$next = $phpcsFile->findNext( \T_DOC_COMMENT_WHITESPACE, ( $tag + 1 ), null, true );
+			if ( $tokens[ $next ]['code'] !== \T_DOC_COMMENT_STRING
 				|| $tokens[ $next ]['line'] !== $tokens[ $tag ]['line']
 			) {
 				$phpcsFile->addError(
@@ -96,7 +96,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 			$annotation                 = $tokens[ $next ]['content'];
 			$coversTags[ "$tag-$next" ] = $annotation;
 
-			if ( preg_match( '`^' . self::VALID_CONTENT_REGEX . '$`', $annotation ) === 1 ) {
+			if ( \preg_match( '`^' . self::VALID_CONTENT_REGEX . '$`', $annotation ) === 1 ) {
 				continue;
 			}
 
@@ -107,7 +107,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 			$errorThrown = false;
 
 			// Check for Union/Intersect types.
-			if ( strpos( $annotation, '&' ) !== false ) {
+			if ( \strpos( $annotation, '&' ) !== false ) {
 				if ( $this->fixAnnotationToSplit( $phpcsFile, $next, 'IntersectFound', '&' ) === true ) {
 					continue;
 				}
@@ -115,7 +115,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 				$errorThrown = true;
 			}
 
-			if ( strpos( $annotation, '|' ) !== false ) {
+			if ( \strpos( $annotation, '|' ) !== false ) {
 				if ( $this->fixAnnotationToSplit( $phpcsFile, $next, 'UnionFound', '|' ) === true ) {
 					continue;
 				}
@@ -124,16 +124,15 @@ public function process( File $phpcsFile, $stackPtr ) {
 			}
 
 			// Parentheses/Braces at the end of the annotation.
-			$expected = rtrim( $annotation, '(){} ' );
+			$expected = \rtrim( $annotation, '(){} ' );
 			if ( $this->fixSimpleError( $phpcsFile, $next, $expected, 'InvalidBraces' ) === true ) {
 				$errorThrown = true;
-
 			}
 
 			// Incorrect `<public|protected|private>` annotation.
-			if ( preg_match( '`::[{(\[]?(!)?(public|protected|private)[})\]]?`', $annotation, $matches ) === 1 ) {
+			if ( \preg_match( '`::[{(\[]?(!)?(public|protected|private)[})\]]?`', $annotation, $matches ) === 1 ) {
 				$replacement = '::<' . $matches[1] . $matches[2] . '>';
-				$expected    = str_replace( $matches[0], $replacement, $annotation );
+				$expected    = \str_replace( $matches[0], $replacement, $annotation );
 
 				if ( $this->fixSimpleError( $phpcsFile, $next, $expected, 'InvalidFunctionGroup' ) === true ) {
 					$errorThrown = true;
@@ -152,7 +151,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 			$phpcsFile->addError( $error, $next, 'Invalid', $data );
 		}
 
-		$coversNothingCount = count( $coversNothingTags );
+		$coversNothingCount = \count( $coversNothingTags );
 		if ( $firstCoversTag !== false && $coversNothingCount > 0 ) {
 			$error = 'A test can\'t both cover something as well as cover nothing. First @coversNothing tag encountered on line %d; first @covers tag encountered on line %d';
 			$data  = [
@@ -166,11 +165,10 @@ public function process( File $phpcsFile, $stackPtr ) {
 		if ( $coversNothingCount > 1 ) {
 			$error      = 'Only one @coversNothing tag allowed per test';
 			$code       = 'DuplicateCoversNothing';
-			$fixable    = true;
 			$removeTags = [];
-			foreach ( $coversNothingTags as $position => $ptr ) {
+			foreach ( $coversNothingTags as $ptr ) {
 				$next = ( $ptr + 1 );
-				if ( $tokens[ $next ]['code'] === T_DOC_COMMENT_WHITESPACE
+				if ( $tokens[ $next ]['code'] === \T_DOC_COMMENT_WHITESPACE
 					&& $tokens[ $next ]['content'] === $phpcsFile->eolChar
 				) {
 					// No comment, ok to remove.
@@ -178,7 +176,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 				}
 			}
 
-			$removalCount = count( $removeTags );
+			$removalCount = \count( $removeTags );
 			if ( ( $coversNothingCount - $removalCount ) > 1 ) {
 				// More than one tag had a comment.
 				$phpcsFile->addError( $error, $tokens[ $stackPtr ]['comment_closer'], $code );
@@ -212,11 +210,11 @@ public function process( File $phpcsFile, $stackPtr ) {
 			}
 		}
 
-		$coversCount = count( $coversTags );
+		$coversCount = \count( $coversTags );
 		if ( $coversCount > 1 ) {
-			$unique = array_unique( $coversTags );
-			if ( count( $unique ) !== $coversCount ) {
-				$value_count = array_count_values( $coversTags );
+			$unique = \array_unique( $coversTags );
+			if ( \count( $unique ) !== $coversCount ) {
+				$value_count = \array_count_values( $coversTags );
 				$error       = 'Duplicate @covers tag found. First tag with the same annotation encountered on line %d';
 				$code        = 'DuplicateCovers';
 				foreach ( $value_count as $annotation => $count ) {
@@ -231,12 +229,12 @@ public function process( File $phpcsFile, $stackPtr ) {
 						}
 
 						if ( ! isset( $first ) ) {
-							$first = explode( '-', $ptrs );
+							$first = \explode( '-', $ptrs );
 							$data  = [ $tokens[ $first[0] ]['line'] ];
 							continue;
 						}
 
-						$ptrs = explode( '-', $ptrs );
+						$ptrs = \explode( '-', $ptrs );
 
 						$fix = $phpcsFile->addFixableError( $error, $ptrs[0], $code, $data );
 						if ( $fix === true ) {
@@ -246,7 +244,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 							// Remove the whole line.
 							for ( $i = ( $ptrs[1] ); $i >= 0; $i-- ) {
 								if ( $tokens[ $i ]['line'] !== $tokens[ $ptrs[1] ]['line'] ) {
-									if ( $tokens[ $i ]['code'] === T_DOC_COMMENT_WHITESPACE
+									if ( $tokens[ $i ]['code'] === \T_DOC_COMMENT_WHITESPACE
 										&& $tokens[ $i ]['content'] === $phpcsFile->eolChar
 									) {
 										$phpcsFile->fixer->replaceToken( $i, '' );
@@ -282,7 +280,7 @@ protected function fixSimpleError( File $phpcsFile, $stackPtr, $expected, $error
 		$annotation = $tokens[ $stackPtr ]['content'];
 
 		if ( $expected === $annotation
-			|| preg_match( '`^' . self::VALID_CONTENT_REGEX . '$`', $expected ) !== 1
+			|| \preg_match( '`^' . self::VALID_CONTENT_REGEX . '$`', $expected ) !== 1
 		) {
 			return false;
 		}
@@ -323,9 +321,9 @@ protected function fixAnnotationToSplit( File $phpcsFile, $stackPtr, $errorCode,
 		if ( $fix === true ) {
 			$tokens      = $phpcsFile->getTokens();
 			$annotation  = $tokens[ $stackPtr ]['content'];
-			$annotations = explode( $separator, $annotation );
-			$annotations = array_map( 'trim', $annotations );
-			$annotations = array_filter( $annotations ); // Remove empties.
+			$annotations = \explode( $separator, $annotation );
+			$annotations = \array_map( 'trim', $annotations );
+			$annotations = \array_filter( $annotations ); // Remove empties.
 
 			$phpcsFile->fixer->beginChangeset();
 			$phpcsFile->fixer->replaceToken( $stackPtr, '' );
diff --git a/Yoast/Sniffs/Commenting/FileCommentSniff.php b/Yoast/Sniffs/Commenting/FileCommentSniff.php
index 6a112b57..efd7e763 100644
--- a/Yoast/Sniffs/Commenting/FileCommentSniff.php
+++ b/Yoast/Sniffs/Commenting/FileCommentSniff.php
@@ -40,7 +40,7 @@ class FileCommentSniff extends Squiz_FileCommentSniff {
 	 */
 	public function process( File $phpcsFile, $stackPtr ) {
 
-		$namespace_token = $phpcsFile->findNext( T_NAMESPACE, $stackPtr );
+		$namespace_token = $phpcsFile->findNext( \T_NAMESPACE, $stackPtr );
 		if ( $namespace_token === false ) {
 			// No namespace found, fall through to parent sniff.
 			return parent::process( $phpcsFile, $stackPtr );
@@ -50,18 +50,18 @@ public function process( File $phpcsFile, $stackPtr ) {
 
 		$next_non_empty = $phpcsFile->findNext( Tokens::$emptyTokens, ( $namespace_token + 1 ), null, true );
 		if ( $next_non_empty === false
-			|| $tokens[ $next_non_empty ]['code'] === T_SEMICOLON
-			|| $tokens[ $next_non_empty ]['code'] === T_OPEN_CURLY_BRACKET
-			|| $tokens[ $next_non_empty ]['code'] === T_NS_SEPARATOR
+			|| $tokens[ $next_non_empty ]['code'] === \T_SEMICOLON
+			|| $tokens[ $next_non_empty ]['code'] === \T_OPEN_CURLY_BRACKET
+			|| $tokens[ $next_non_empty ]['code'] === \T_NS_SEPARATOR
 		) {
 			// Either live coding, global namespace (i.e. not really namespaced) or namespace operator.
 			// Fall through to parent sniff.
 			return parent::process( $phpcsFile, $stackPtr );
 		}
 
-		$comment_start = $phpcsFile->findNext( T_WHITESPACE, ( $stackPtr + 1 ), $namespace_token, true );
+		$comment_start = $phpcsFile->findNext( \T_WHITESPACE, ( $stackPtr + 1 ), $namespace_token, true );
 
-		if ( $tokens[ $comment_start ]['code'] === T_DOC_COMMENT_OPEN_TAG ) {
+		if ( $tokens[ $comment_start ]['code'] === \T_DOC_COMMENT_OPEN_TAG ) {
 			$phpcsFile->addWarning(
 				'A file containing a (named) namespace declaration does not need a file docblock',
 				$comment_start,
diff --git a/Yoast/Sniffs/Commenting/TestsHaveCoversTagSniff.php b/Yoast/Sniffs/Commenting/TestsHaveCoversTagSniff.php
index c8ec5527..f6279c94 100644
--- a/Yoast/Sniffs/Commenting/TestsHaveCoversTagSniff.php
+++ b/Yoast/Sniffs/Commenting/TestsHaveCoversTagSniff.php
@@ -19,12 +19,12 @@ class TestsHaveCoversTagSniff implements Sniff {
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
-	 * @return array
+	 * @return (int|string)[]
 	 */
 	public function register() {
 		return [
-			T_CLASS,
-			T_FUNCTION,
+			\T_CLASS,
+			\T_FUNCTION,
 		];
 	}
 
@@ -43,11 +43,11 @@ public function process( File $phpcsFile, $stackPtr ) {
 
 		$tokens = $phpcsFile->getTokens();
 
-		if ( $tokens[ $stackPtr ]['code'] === T_CLASS ) {
+		if ( $tokens[ $stackPtr ]['code'] === \T_CLASS ) {
 			return $this->process_class( $phpcsFile, $stackPtr );
 		}
 
-		if ( $tokens[ $stackPtr ]['code'] === T_FUNCTION ) {
+		if ( $tokens[ $stackPtr ]['code'] === \T_FUNCTION ) {
 			return $this->process_function( $phpcsFile, $stackPtr );
 		}
 	}
@@ -66,7 +66,7 @@ protected function process_class( File $phpcsFile, $stackPtr ) {
 		$tokens = $phpcsFile->getTokens();
 		$name   = $phpcsFile->getDeclarationName( $stackPtr );
 
-		if ( substr( $name, -4 ) !== 'Test' ) {
+		if ( \substr( $name, -4 ) !== 'Test' ) {
 			// Not a test class.
 			if ( isset( $tokens[ $stackPtr ]['scope_closer'] ) ) {
 				// No need to examine the methods in this class.
@@ -78,9 +78,9 @@ protected function process_class( File $phpcsFile, $stackPtr ) {
 
 		// @todo: Once PHPCS 3.5.0 is out, replace with call to new findCommentAboveOOStructure() method.
 		$find = [
-			T_WHITESPACE,
-			T_ABSTRACT,
-			T_FINAL,
+			\T_WHITESPACE,
+			\T_ABSTRACT,
+			\T_FINAL,
 		];
 
 		$commentEnd = $stackPtr;
@@ -88,7 +88,7 @@ protected function process_class( File $phpcsFile, $stackPtr ) {
 			$commentEnd = $phpcsFile->findPrevious( $find, ( $commentEnd - 1 ), null, true );
 		} while ( $tokens[ $commentEnd ]['line'] === $tokens[ $stackPtr ]['line'] );
 
-		if ( $tokens[ $commentEnd ]['code'] !== T_DOC_COMMENT_CLOSE_TAG
+		if ( $tokens[ $commentEnd ]['code'] !== \T_DOC_COMMENT_CLOSE_TAG
 			|| $tokens[ $commentEnd ]['line'] !== ( $tokens[ $stackPtr ]['line'] - 1 )
 		) {
 			// Class without (proper) docblock. Not our concern.
@@ -131,14 +131,14 @@ protected function process_function( File $phpcsFile, $stackPtr ) {
 
 		// @todo: Once PHPCS 3.5.0 is out, replace with call to new findCommentAboveOOStructure() method.
 		$find   = Tokens::$methodPrefixes;
-		$find[] = T_WHITESPACE;
+		$find[] = \T_WHITESPACE;
 
 		$commentEnd = $stackPtr;
 		do {
 			$commentEnd = $phpcsFile->findPrevious( $find, ( $commentEnd - 1 ), null, true );
 		} while ( $tokens[ $commentEnd ]['line'] === $tokens[ $stackPtr ]['line'] );
 
-		if ( $tokens[ $commentEnd ]['code'] !== T_DOC_COMMENT_CLOSE_TAG
+		if ( $tokens[ $commentEnd ]['code'] !== \T_DOC_COMMENT_CLOSE_TAG
 			|| $tokens[ $commentEnd ]['line'] !== ( $tokens[ $stackPtr ]['line'] - 1 )
 		) {
 			// Function without (proper) docblock. Not our concern.
@@ -168,7 +168,7 @@ protected function process_function( File $phpcsFile, $stackPtr ) {
 		}
 
 		$name = $phpcsFile->getDeclarationName( $stackPtr );
-		if ( stripos( $name, 'test' ) !== 0 && $foundTest === false ) {
+		if ( \stripos( $name, 'test' ) !== 0 && $foundTest === false ) {
 			// Not a test method.
 			return;
 		}
diff --git a/Yoast/Sniffs/ControlStructures/IfElseDeclarationSniff.php b/Yoast/Sniffs/ControlStructures/IfElseDeclarationSniff.php
index d9e68782..5c654da1 100644
--- a/Yoast/Sniffs/ControlStructures/IfElseDeclarationSniff.php
+++ b/Yoast/Sniffs/ControlStructures/IfElseDeclarationSniff.php
@@ -20,12 +20,12 @@ class IfElseDeclarationSniff implements Sniff {
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
-	 * @return array
+	 * @return (int|string)[]
 	 */
 	public function register() {
 		return [
-			T_ELSE,
-			T_ELSEIF,
+			\T_ELSE,
+			\T_ELSEIF,
 		];
 	}
 
@@ -47,24 +47,24 @@ public function process( File $phpcsFile, $stackPtr ) {
 		else {
 			// Deal with "else if".
 			$next = $phpcsFile->findNext( Tokens::$emptyTokens, ( $stackPtr + 1 ), null, true );
-			if ( $tokens[ $next ]['code'] === T_IF && isset( $tokens[ $next ]['scope_opener'] ) ) {
+			if ( $tokens[ $next ]['code'] === \T_IF && isset( $tokens[ $next ]['scope_opener'] ) ) {
 				$scope_open = $tokens[ $next ]['scope_opener'];
 			}
 		}
 
-		if ( ! isset( $scope_open ) || $tokens[ $scope_open ]['code'] === T_COLON ) {
+		if ( ! isset( $scope_open ) || $tokens[ $scope_open ]['code'] === \T_COLON ) {
 			// No scope opener found or alternative syntax (not our concern).
 			return;
 		}
 
-		$previous_scope_closer = $phpcsFile->findPrevious( T_CLOSE_CURLY_BRACKET, ( $stackPtr - 1 ) );
+		$previous_scope_closer = $phpcsFile->findPrevious( \T_CLOSE_CURLY_BRACKET, ( $stackPtr - 1 ) );
 
 		if ( $tokens[ $previous_scope_closer ]['line'] === $tokens[ $stackPtr ]['line'] ) {
 			$phpcsFile->addError(
 				'%s statement must be on a new line',
 				$stackPtr,
 				'NewLine',
-				[ ucfirst( $tokens[ $stackPtr ]['content'] ) ]
+				[ \ucfirst( $tokens[ $stackPtr ]['content'] ) ]
 			);
 		}
 		elseif ( $tokens[ $previous_scope_closer ]['column'] !== $tokens[ $stackPtr ]['column'] ) {
@@ -72,7 +72,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 				'%s statement not aligned with previous part of the control structure',
 				$stackPtr,
 				'Alignment',
-				[ ucfirst( $tokens[ $stackPtr ]['content'] ) ]
+				[ \ucfirst( $tokens[ $stackPtr ]['content'] ) ]
 			);
 		}
 
@@ -82,7 +82,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 			$error = 'Nothing but whitespace and comments allowed between closing bracket and %s statement, found "%s"';
 			$data  = [
 				$tokens[ $stackPtr ]['content'],
-				trim( $phpcsFile->getTokensAsString( ( $previous_scope_closer + 1 ), ( $stackPtr - ( $previous_scope_closer + 1 ) ) ) ),
+				\trim( $phpcsFile->getTokensAsString( ( $previous_scope_closer + 1 ), ( $stackPtr - ( $previous_scope_closer + 1 ) ) ) ),
 			];
 			$phpcsFile->addError( $error, $stackPtr, 'StatementFound', $data );
 		}
diff --git a/Yoast/Sniffs/Files/FileNameSniff.php b/Yoast/Sniffs/Files/FileNameSniff.php
index 5e499e2d..19f59d2e 100644
--- a/Yoast/Sniffs/Files/FileNameSniff.php
+++ b/Yoast/Sniffs/Files/FileNameSniff.php
@@ -62,21 +62,21 @@ class FileNameSniff implements Sniff {
 	/**
 	 * Object tokens to search for in a file.
 	 *
-	 * @var array
+	 * @var (int|string)[]
 	 */
 	private $oo_tokens = [
-		T_CLASS,
-		T_INTERFACE,
-		T_TRAIT,
+		\T_CLASS,
+		\T_INTERFACE,
+		\T_TRAIT,
 	];
 
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
-	 * @return array
+	 * @return (int|string)[]
 	 */
 	public function register() {
-		return [ T_OPEN_TAG ];
+		return [ \T_OPEN_TAG ];
 	}
 
 	/**
@@ -91,13 +91,13 @@ public function register() {
 	 */
 	public function process( File $phpcsFile, $stackPtr ) {
 		// Stripping potential quotes to ensure `stdin_path` passed by IDEs does not include quotes.
-		$file = preg_replace( '`^([\'"])(.*)\1$`Ds', '$2', $phpcsFile->getFileName() );
+		$file = \preg_replace( '`^([\'"])(.*)\1$`Ds', '$2', $phpcsFile->getFileName() );
 
 		if ( $file === 'STDIN' ) {
 			return;
 		}
 
-		$path_info = pathinfo( $file );
+		$path_info = \pathinfo( $file );
 
 		// Basename = filename + extension.
 		$basename = '';
@@ -117,7 +117,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 
 		$error      = 'Filenames should be all lowercase with hyphens as word separators. Expected %s, but found %s.';
 		$error_code = 'NotHyphenatedLowercase';
-		$expected   = strtolower( str_replace( '_', '-', $file_name ) );
+		$expected   = \strtolower( \str_replace( '_', '-', $file_name ) );
 
 		if ( $this->is_file_excluded( $phpcsFile, $file ) === false ) {
 			$oo_structure = $phpcsFile->findNext( $this->oo_tokens, $stackPtr );
@@ -129,52 +129,52 @@ public function process( File $phpcsFile, $stackPtr ) {
 				$prefixes = $this->clean_custom_array_property( $this->oo_prefixes );
 				if ( ! empty( $prefixes ) ) {
 					// Use reverse natural sorting to get the longest of overlapping prefixes first.
-					rsort( $prefixes, ( SORT_NATURAL | SORT_FLAG_CASE ) );
+					\rsort( $prefixes, ( \SORT_NATURAL | \SORT_FLAG_CASE ) );
 					foreach ( $prefixes as $prefix ) {
-						if ( $name !== $prefix && stripos( $name, $prefix ) === 0 ) {
-							$name = substr( $name, strlen( $prefix ) );
-							$name = ltrim( $name, '_-' );
+						if ( $name !== $prefix && \stripos( $name, $prefix ) === 0 ) {
+							$name = \substr( $name, \strlen( $prefix ) );
+							$name = \ltrim( $name, '_-' );
 							break;
 						}
 					}
 				}
 
-				$expected = strtolower( str_replace( '_', '-', $name ) );
+				$expected = \strtolower( \str_replace( '_', '-', $name ) );
 
 				switch ( $tokens[ $oo_structure ]['code'] ) {
-					case T_CLASS:
+					case \T_CLASS:
 						$error      = 'Class file names should be based on the class name without the plugin prefix. Expected %s, but found %s.';
 						$error_code = 'InvalidClassFileName';
 						break;
 
-					case T_INTERFACE:
+					case \T_INTERFACE:
 						$error      = 'Interface file names should be based on the interface name without the plugin prefix and should have "-interface" as a suffix. Expected %s, but found %s.';
 						$error_code = 'InvalidInterfaceFileName';
 
 						// Don't duplicate "interface" in the filename.
-						if ( substr( $expected, -10 ) !== '-interface' ) {
+						if ( \substr( $expected, -10 ) !== '-interface' ) {
 							$expected .= '-interface';
 						}
 						break;
 
-					case T_TRAIT:
+					case \T_TRAIT:
 						$error      = 'Trait file names should be based on the trait name without the plugin prefix and should have "-trait" as a suffix. Expected %s, but found %s.';
 						$error_code = 'InvalidTraitFileName';
 
 						// Don't duplicate "trait" in the filename.
-						if ( substr( $expected, -6 ) !== '-trait' ) {
+						if ( \substr( $expected, -6 ) !== '-trait' ) {
 							$expected .= '-trait';
 						}
 						break;
 				}
 			}
 			else {
-				$has_function = $phpcsFile->findNext( T_FUNCTION, $stackPtr );
+				$has_function = $phpcsFile->findNext( \T_FUNCTION, $stackPtr );
 				if ( $has_function !== false ) {
 					$error      = 'Files containing function declarations should have "-functions" as a suffix. Expected %s, but found %s.';
 					$error_code = 'InvalidFunctionsFileName';
 
-					if ( substr( $expected, -10 ) !== '-functions' ) {
+					if ( \substr( $expected, -10 ) !== '-functions' ) {
 						$expected .= '-functions';
 					}
 				}
@@ -211,7 +211,7 @@ protected function is_file_excluded( File $phpcsFile, $path_to_file ) {
 		$exclude = $this->clean_custom_array_property( $this->excluded_files_strict_check, true, true );
 
 		if ( ! empty( $exclude ) ) {
-			$exclude      = array_map( [ $this, 'normalize_directory_separators' ], $exclude );
+			$exclude      = \array_map( [ $this, 'normalize_directory_separators' ], $exclude );
 			$path_to_file = $this->normalize_directory_separators( $path_to_file );
 
 			if ( ! isset( $phpcsFile->config->basepath ) ) {
@@ -227,7 +227,7 @@ protected function is_file_excluded( File $phpcsFile, $path_to_file ) {
 			}
 
 			// Lowercase the filename to not interfere with the lowercase/dashes rule.
-			$path_to_file = strtolower( ltrim( $path_to_file, '/' ) );
+			$path_to_file = \strtolower( \ltrim( $path_to_file, '/' ) );
 
 			if ( isset( $exclude[ $path_to_file ] ) ) {
 				// Filename is on the exclude list.
@@ -251,17 +251,17 @@ protected function is_file_excluded( File $phpcsFile, $path_to_file ) {
 	 * @param bool  $flip     Whether to flip the array values to keys.
 	 * @param bool  $to_lower Whether to lowercase the array values.
 	 *
-	 * @return array
+	 * @return (string|bool)[]
 	 */
 	protected function clean_custom_array_property( $property, $flip = false, $to_lower = false ) {
-		$property = array_filter( array_map( 'trim', $property ) );
+		$property = \array_filter( \array_map( 'trim', $property ) );
 
 		if ( $to_lower === true ) {
-			$property = array_map( 'strtolower', $property );
+			$property = \array_map( 'strtolower', $property );
 		}
 
 		if ( $flip === true ) {
-			$property = array_fill_keys( $property, false );
+			$property = \array_fill_keys( $property, false );
 		}
 
 		return $property;
@@ -275,6 +275,6 @@ protected function clean_custom_array_property( $property, $flip = false, $to_lo
 	 * @return string
 	 */
 	private function normalize_directory_separators( $path ) {
-		return ltrim( strtr( $path, '\\', '/' ), '/' );
+		return \ltrim( \strtr( $path, '\\', '/' ), '/' );
 	}
 }
diff --git a/Yoast/Sniffs/Files/TestDoublesSniff.php b/Yoast/Sniffs/Files/TestDoublesSniff.php
index 33359866..1898a271 100644
--- a/Yoast/Sniffs/Files/TestDoublesSniff.php
+++ b/Yoast/Sniffs/Files/TestDoublesSniff.php
@@ -31,7 +31,7 @@ class TestDoublesSniff implements Sniff {
 	 * @since 1.1.0 The property type has changed from string to array.
 	 *              Use of this property with a string value has been deprecated.
 	 *
-	 * @var array
+	 * @var string[]
 	 */
 	public $doubles_path = [
 		'/tests/doubles',
@@ -41,20 +41,20 @@ class TestDoublesSniff implements Sniff {
 	 * Validated absolute target paths for test double/mock classes or an empty array
 	 * if the intended target directory/directories don't exist.
 	 *
-	 * @var array
+	 * @var string[]
 	 */
 	protected $target_paths;
 
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
-	 * @return array
+	 * @return (int|string)[]
 	 */
 	public function register() {
 		return [
-			T_CLASS,
-			T_INTERFACE,
-			T_TRAIT,
+			\T_CLASS,
+			\T_INTERFACE,
+			\T_TRAIT,
 		];
 	}
 
@@ -70,7 +70,7 @@ public function register() {
 	 */
 	public function process( File $phpcsFile, $stackPtr ) {
 		// Stripping potential quotes to ensure `stdin_path` passed by IDEs does not include quotes.
-		$file = preg_replace( '`^([\'"])(.*)\1$`Ds', '$2', $phpcsFile->getFileName() );
+		$file = \preg_replace( '`^([\'"])(.*)\1$`Ds', '$2', $phpcsFile->getFileName() );
 
 		if ( $file === 'STDIN' ) {
 			return;
@@ -81,7 +81,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 			return;
 		}
 
-		if ( stripos( $object_name, 'mock' ) === false && stripos( $object_name, 'double' ) === false ) {
+		if ( \stripos( $object_name, 'mock' ) === false && \stripos( $object_name, 'double' ) === false ) {
 			return;
 		}
 
@@ -111,23 +111,23 @@ public function process( File $phpcsFile, $stackPtr ) {
 		 *
 		 * {@internal This should be removed in YoastCS 2.0.0.}}
 		 */
-		if ( is_string( $this->doubles_path ) ) {
+		if ( \is_string( $this->doubles_path ) ) {
 			$this->doubles_path = (array) $this->doubles_path;
 		}
 
 		$tokens    = $phpcsFile->getTokens();
 		$base_path = $this->normalize_directory_separators( $phpcsFile->config->basepath );
-		$base_path = rtrim( $base_path, '/' ) . '/'; // Make sure the base_path ends in a single slash.
+		$base_path = \rtrim( $base_path, '/' ) . '/'; // Make sure the base_path ends in a single slash.
 
-		if ( ! isset( $this->target_paths ) || defined( 'PHP_CODESNIFFER_IN_TESTS' ) ) {
+		if ( ! isset( $this->target_paths ) || \defined( 'PHP_CODESNIFFER_IN_TESTS' ) ) {
 			$this->target_paths = [];
 
 			foreach ( $this->doubles_path as $doubles_path ) {
 				$target_path  = $base_path;
-				$target_path .= trim( $this->normalize_directory_separators( $doubles_path ), '/' ) . '/';
+				$target_path .= \trim( $this->normalize_directory_separators( $doubles_path ), '/' ) . '/';
 
-				if ( file_exists( $target_path ) && is_dir( $target_path ) ) {
-					$this->target_paths[] = strtolower( $target_path );
+				if ( \file_exists( $target_path ) && \is_dir( $target_path ) ) {
+					$this->target_paths[] = \strtolower( $target_path );
 				}
 			}
 		}
@@ -138,13 +138,13 @@ public function process( File $phpcsFile, $stackPtr ) {
 				$phpcsFile->config->basepath,
 			];
 
-			if ( count( $this->doubles_path ) === 1 ) {
+			if ( \count( $this->doubles_path ) === 1 ) {
 				$data[] = 'directory';
-				$data[] = implode( '', $this->doubles_path );
+				$data[] = \implode( '', $this->doubles_path );
 			}
 			else {
-				$all_paths = implode( '", "', $this->doubles_path );
-				$all_paths = substr_replace( $all_paths, ' and', strrpos( $all_paths, ',' ), 1 );
+				$all_paths = \implode( '", "', $this->doubles_path );
+				$all_paths = \substr_replace( $all_paths, ' and', \strrpos( $all_paths, ',' ), 1 );
 
 				$data[] = 'directories';
 				$data[] = $all_paths;
@@ -162,7 +162,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 			$is_error     = true;
 
 			foreach ( $this->target_paths as $target_path ) {
-				if ( stripos( $path_to_file, $target_path ) !== false ) {
+				if ( \stripos( $path_to_file, $target_path ) !== false ) {
 					$is_error = false;
 					break;
 				}
@@ -213,6 +213,6 @@ public function process( File $phpcsFile, $stackPtr ) {
 	 * @return string
 	 */
 	private function normalize_directory_separators( $path ) {
-		return strtr( $path, '\\', '/' );
+		return \strtr( $path, '\\', '/' );
 	}
 }
diff --git a/Yoast/Sniffs/Namespaces/NamespaceDeclarationSniff.php b/Yoast/Sniffs/Namespaces/NamespaceDeclarationSniff.php
index 4fcba833..6d11b1ea 100644
--- a/Yoast/Sniffs/Namespaces/NamespaceDeclarationSniff.php
+++ b/Yoast/Sniffs/Namespaces/NamespaceDeclarationSniff.php
@@ -27,11 +27,11 @@ class NamespaceDeclarationSniff implements Sniff {
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
-	 * @return array
+	 * @return (int|string)[]
 	 */
 	public function register() {
 		return [
-			T_OPEN_TAG,
+			\T_OPEN_TAG,
 		];
 	}
 
@@ -50,7 +50,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 
 		$statements = [];
 
-		while ( ( $stackPtr = $phpcsFile->findNext( T_NAMESPACE, ( $stackPtr + 1 ) ) ) !== false ) {
+		while ( ( $stackPtr = $phpcsFile->findNext( \T_NAMESPACE, ( $stackPtr + 1 ) ) ) !== false ) {
 
 			$next_non_empty = $phpcsFile->findNext( Tokens::$emptyTokens, ( $stackPtr + 1 ), null, true );
 			if ( $next_non_empty === false ) {
@@ -58,7 +58,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 				break;
 			}
 
-			if ( $tokens[ $next_non_empty ]['code'] === T_NS_SEPARATOR ) {
+			if ( $tokens[ $next_non_empty ]['code'] === \T_NS_SEPARATOR ) {
 				// Not a namespace declaration, but the use of the namespace keyword as operator.
 				continue;
 			}
@@ -77,8 +77,8 @@ public function process( File $phpcsFile, $stackPtr ) {
 				);
 			}
 
-			if ( $tokens[ $next_non_empty ]['code'] === T_SEMICOLON
-				|| $tokens[ $next_non_empty ]['code'] === T_OPEN_CURLY_BRACKET
+			if ( $tokens[ $next_non_empty ]['code'] === \T_SEMICOLON
+				|| $tokens[ $next_non_empty ]['code'] === \T_OPEN_CURLY_BRACKET
 			) {
 				// Namespace declaration without namespace name (= global namespace).
 				$phpcsFile->addError(
@@ -89,7 +89,7 @@ public function process( File $phpcsFile, $stackPtr ) {
 			}
 		}
 
-		$count = count( $statements );
+		$count = \count( $statements );
 		if ( $count > 1 ) {
 			$data = [
 				$count,
diff --git a/Yoast/Sniffs/NamingConventions/NamespaceNameSniff.php b/Yoast/Sniffs/NamingConventions/NamespaceNameSniff.php
index ae400ffd..10830eba 100644
--- a/Yoast/Sniffs/NamingConventions/NamespaceNameSniff.php
+++ b/Yoast/Sniffs/NamingConventions/NamespaceNameSniff.php
@@ -88,18 +88,18 @@ class NamespaceNameSniff implements Sniff {
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
-	 * @return array
+	 * @return (int|string)[]
 	 */
 	public function register() {
-		return [ T_NAMESPACE ];
+		return [ \T_NAMESPACE ];
 	}
 
 	/**
 	 * Filter out all prefixes which don't have namespace separators.
 	 *
-	 * @param array $prefixes The unvalidated prefixes.
+	 * @param string[] $prefixes The unvalidated prefixes.
 	 *
-	 * @return array
+	 * @return string[]
 	 */
 	protected function filter_prefixes( $prefixes ) {
 		return $this->filter_allow_only_namespace_prefixes( $prefixes );
@@ -112,8 +112,7 @@ protected function filter_prefixes( $prefixes ) {
 	 * @param int                         $stackPtr  The position of the current token
 	 *                                               in the stack passed in $tokens.
 	 *
-	 * @return int StackPtr to the end of the file, this sniff needs to only
-	 *             check each file once.
+	 * @return void
 	 */
 	public function process( File $phpcsFile, $stackPtr ) {
 
@@ -125,19 +124,19 @@ public function process( File $phpcsFile, $stackPtr ) {
 		}
 
 		$next_non_empty = $phpcsFile->findNext( Tokens::$emptyTokens, ( $stackPtr + 1 ), null, true );
-		if ( $tokens[ $next_non_empty ]['code'] === T_NS_SEPARATOR ) {
+		if ( $tokens[ $next_non_empty ]['code'] === \T_NS_SEPARATOR ) {
 			// Not a namespace declaration.
 			return;
 		}
 
 		// Get the complete namespace name.
 		$namespace_name = $tokens[ $next_non_empty ]['content'];
-		for ( $i = ( $next_non_empty + 1 ); ; $i++ ) {
+		for ( $i = ( $next_non_empty + 1 ); $i < $phpcsFile->numTokens; $i++ ) {
 			if ( isset( Tokens::$emptyTokens[ $tokens[ $i ]['code'] ] ) ) {
 				continue;
 			}
 
-			if ( $tokens[ $i ]['code'] !== T_STRING && $tokens[ $i ]['code'] !== T_NS_SEPARATOR ) {
+			if ( $tokens[ $i ]['code'] !== \T_STRING && $tokens[ $i ]['code'] !== \T_NS_SEPARATOR ) {
 				// Reached end of the namespace declaration.
 				break;
 			}
@@ -145,6 +144,11 @@ public function process( File $phpcsFile, $stackPtr ) {
 			$namespace_name .= $tokens[ $i ]['content'];
 		}
 
+		if ( $i === $phpcsFile->numTokens ) {
+			// Live coding.
+			return;
+		}
+
 		$this->validate_prefixes();
 
 		// Strip off the plugin prefix.
@@ -153,9 +157,9 @@ public function process( File $phpcsFile, $stackPtr ) {
 		if ( ! empty( $this->validated_prefixes ) ) {
 			$name = $namespace_name . '\\'; // Validated prefixes always have a \ at the end.
 			foreach ( $this->validated_prefixes as $prefix ) {
-				if ( strpos( $name . '\\', $prefix ) === 0 ) {
-					$namespace_name_no_prefix = rtrim( substr( $name, strlen( $prefix ) ), '\\' );
-					$found_prefix             = rtrim( $prefix, '\\' );
+				if ( \strpos( $name . '\\', $prefix ) === 0 ) {
+					$namespace_name_no_prefix = \rtrim( \substr( $name, \strlen( $prefix ) ), '\\' );
+					$found_prefix             = \rtrim( $prefix, '\\' );
 					break;
 				}
 			}
@@ -168,15 +172,15 @@ public function process( File $phpcsFile, $stackPtr ) {
 		if ( $namespace_name_no_prefix !== '' ) {
 			$namespace_for_level_check = $namespace_name_no_prefix;
 			// Allow for `Tests\` and `Tests\Doubles\` after the prefix.
-			if ( strpos( $namespace_for_level_check, 'Tests\\' ) === 0 ) {
-				$namespace_for_level_check = substr( $namespace_for_level_check, 6 );
-				if ( strpos( $namespace_for_level_check, 'Doubles\\' ) === 0 ) {
-					$namespace_for_level_check = substr( $namespace_for_level_check, 8 );
+			if ( \strpos( $namespace_for_level_check, 'Tests\\' ) === 0 ) {
+				$namespace_for_level_check = \substr( $namespace_for_level_check, 6 );
+				if ( \strpos( $namespace_for_level_check, 'Doubles\\' ) === 0 ) {
+					$namespace_for_level_check = \substr( $namespace_for_level_check, 8 );
 				}
 			}
 
-			$parts      = explode( '\\', $namespace_for_level_check );
-			$part_count = count( $parts );
+			$parts      = \explode( '\\', $namespace_for_level_check );
+			$part_count = \count( $parts );
 
 			if ( $part_count > $this->max_levels ) {
 				$error = 'A namespace name is not allowed to be more than %d levels deep (excluding the prefix). Level depth found: %d in %s';
@@ -212,13 +216,13 @@ public function process( File $phpcsFile, $stackPtr ) {
 		$base_path = $this->normalize_directory_separators( $phpcsFile->config->basepath );
 
 		// Stripping potential quotes to ensure `stdin_path` passed by IDEs does not include quotes.
-		$file = preg_replace( '`^([\'"])(.*)\1$`Ds', '$2', $phpcsFile->getFileName() );
+		$file = \preg_replace( '`^([\'"])(.*)\1$`Ds', '$2', $phpcsFile->getFileName() );
 
 		if ( $file === 'STDIN' ) {
 			return;
 		}
 
-		$directory          = $this->normalize_directory_separators( dirname( $file ) );
+		$directory          = $this->normalize_directory_separators( \dirname( $file ) );
 		$relative_directory = Common::stripBasepath( $directory, $base_path );
 		if ( $relative_directory === '.' ) {
 			$relative_directory = '';
@@ -241,43 +245,40 @@ public function process( File $phpcsFile, $stackPtr ) {
 
 		if ( empty( $this->validated_src_directory ) === false ) {
 			foreach ( $this->validated_src_directory as $subdirectory ) {
-				if ( strpos( $relative_directory, $subdirectory ) !== 0 ) {
+				if ( \strpos( $relative_directory, $subdirectory ) !== 0 ) {
 					continue;
 				}
 
-				$relative_directory = substr( $relative_directory, strlen( $subdirectory ) );
+				$relative_directory = \substr( $relative_directory, \strlen( $subdirectory ) );
 				break;
 			}
 		}
 
 		// Now any potential src directory has been stripped, remove the slashes again.
-		$relative_directory = trim( $relative_directory, '/' );
+		$relative_directory = \trim( $relative_directory, '/' );
 
-		$namespace_name_for_translation = str_replace(
+		$namespace_name_for_translation = \str_replace(
 			[ '_', '\\' ], // Find.
 			[ '-', '/' ],  // Replace with.
 			$namespace_name_no_prefix
 		);
 
-		if ( strcasecmp( $relative_directory, $namespace_name_for_translation ) === 0 ) {
+		if ( \strcasecmp( $relative_directory, $namespace_name_for_translation ) === 0 ) {
 			return;
 		}
 
-		$expected = '';
+		$expected = '[Plugin\Prefix]';
 		if ( $found_prefix !== '' ) {
 			$expected = $found_prefix;
 		}
-		else {
-			$expected = '[Plugin\Prefix]';
-		}
 
 		if ( $relative_directory !== '' ) {
-			$levels = explode( '/', $relative_directory );
-			$levels = array_filter( $levels ); // Remove empties.
+			$levels = \explode( '/', $relative_directory );
+			$levels = \array_filter( $levels ); // Remove empties.
 			foreach ( $levels as $level ) {
-				$words     = explode( '-', $level );
-				$words     = array_map( 'ucfirst', $words );
-				$expected .= '\\' . implode( '_', $words );
+				$words     = \explode( '-', $level );
+				$words     = \array_map( 'ucfirst', $words );
+				$expected .= '\\' . \implode( '_', $words );
 			}
 		}
 
@@ -306,7 +307,7 @@ protected function validate_src_directory() {
 		$this->previous_src_directory = $this->src_directory;
 
 		$src_directory = (array) $this->src_directory;
-		$src_directory = array_filter( array_map( 'trim', $src_directory ) );
+		$src_directory = \array_filter( \array_map( 'trim', $src_directory ) );
 
 		if ( empty( $src_directory ) ) {
 			$this->validated_src_directory = [];
@@ -315,7 +316,7 @@ protected function validate_src_directory() {
 
 		$validated = [];
 		foreach ( $src_directory as $directory ) {
-			if ( strpos( $directory, '..' ) !== false ) {
+			if ( \strpos( $directory, '..' ) !== false ) {
 				// Do not allow walking up the directory hierarchy.
 				continue;
 			}
@@ -327,8 +328,8 @@ protected function validate_src_directory() {
 				continue;
 			}
 
-			if ( strpos( $directory, './' ) === 0 ) {
-				$directory = substr( $directory, 2 );
+			if ( \strpos( $directory, './' ) === 0 ) {
+				$directory = \substr( $directory, 2 );
 			}
 
 			if ( $directory === '' ) {
@@ -339,7 +340,7 @@ protected function validate_src_directory() {
 		}
 
 		// Use reverse natural sorting to get the longest directory first.
-		rsort( $validated, ( SORT_NATURAL | SORT_FLAG_CASE ) );
+		\rsort( $validated, ( \SORT_NATURAL | \SORT_FLAG_CASE ) );
 
 		// Set the validated prefixes cache.
 		$this->validated_src_directory = $validated;
@@ -353,6 +354,6 @@ protected function validate_src_directory() {
 	 * @return string
 	 */
 	private function normalize_directory_separators( $path ) {
-		return trim( strtr( $path, '\\', '/' ), '/' );
+		return \trim( \strtr( $path, '\\', '/' ), '/' );
 	}
 }
diff --git a/Yoast/Sniffs/NamingConventions/ObjectNameDepthSniff.php b/Yoast/Sniffs/NamingConventions/ObjectNameDepthSniff.php
index c20ffa5e..6d3766e7 100644
--- a/Yoast/Sniffs/NamingConventions/ObjectNameDepthSniff.php
+++ b/Yoast/Sniffs/NamingConventions/ObjectNameDepthSniff.php
@@ -44,7 +44,7 @@ class ObjectNameDepthSniff extends WPCS_Sniff {
 	 * The key is the suffix. The value indicates whether this suffix is
 	 * only allowed when the class extends a known test class.
 	 *
-	 * @var array
+	 * @var bool[]
 	 */
 	private $test_suffixes = [
 		'Test'   => true,
@@ -55,13 +55,13 @@ class ObjectNameDepthSniff extends WPCS_Sniff {
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
-	 * @return array
+	 * @return (int|string)[]
 	 */
 	public function register() {
 		return [
-			T_CLASS,
-			T_INTERFACE,
-			T_TRAIT,
+			\T_CLASS,
+			\T_INTERFACE,
+			\T_TRAIT,
 		];
 	}
 
@@ -85,20 +85,20 @@ public function process_token( $stackPtr ) {
 			return;
 		}
 
-		$parts      = explode( '_', $object_name );
-		$part_count = count( $parts );
+		$parts      = \explode( '_', $object_name );
+		$part_count = \count( $parts );
 
 		/*
 		 * Allow the class name to be one part longer for confirmed test/mock/double classes.
 		 */
-		$last = array_pop( $parts );
+		$last = \array_pop( $parts );
 		if ( isset( $this->test_suffixes[ $last ] ) ) {
 			if ( $this->test_suffixes[ $last ] === true && $this->is_test_class( $stackPtr ) ) {
 				--$part_count;
 			}
 			else {
 				$extends = $this->phpcsFile->findExtendedClassName( $stackPtr );
-				if ( is_string( $extends ) ) {
+				if ( \is_string( $extends ) ) {
 					--$part_count;
 				}
 			}
@@ -110,13 +110,13 @@ public function process_token( $stackPtr ) {
 
 		// Check if the class is deprecated.
 		$find = [
-			T_ABSTRACT   => T_ABSTRACT,
-			T_FINAL      => T_FINAL,
-			T_WHITESPACE => T_WHITESPACE,
+			\T_ABSTRACT   => \T_ABSTRACT,
+			\T_FINAL      => \T_FINAL,
+			\T_WHITESPACE => \T_WHITESPACE,
 		];
 
 		$comment_end = $this->phpcsFile->findPrevious( $find, ( $stackPtr - 1 ), null, true );
-		if ( $this->tokens[ $comment_end ]['code'] === T_DOC_COMMENT_CLOSE_TAG ) {
+		if ( $this->tokens[ $comment_end ]['code'] === \T_DOC_COMMENT_CLOSE_TAG ) {
 			// Only check if the class has a docblock.
 			$comment_start = $this->tokens[ $comment_end ]['comment_opener'];
 			foreach ( $this->tokens[ $comment_start ]['comment_tags'] as $tag ) {
diff --git a/Yoast/Sniffs/NamingConventions/ValidHookNameSniff.php b/Yoast/Sniffs/NamingConventions/ValidHookNameSniff.php
index 13c5a7a4..54ded3cc 100644
--- a/Yoast/Sniffs/NamingConventions/ValidHookNameSniff.php
+++ b/Yoast/Sniffs/NamingConventions/ValidHookNameSniff.php
@@ -115,9 +115,9 @@ public function process_parameters( $stackPtr, $group_name, $matched_content, $p
 			$found_prefix    = '';
 
 			if ( isset( Tokens::$stringTokens[ $this->tokens[ $first_non_empty ]['code'] ] ) ) {
-				$content = trim( $this->strip_quotes( $this->tokens[ $first_non_empty ]['content'] ) );
+				$content = \trim( $this->strip_quotes( $this->tokens[ $first_non_empty ]['content'] ) );
 				foreach ( $this->validated_prefixes as $prefix ) {
-					if ( strpos( $content, $prefix ) === 0 ) {
+					if ( \strpos( $content, $prefix ) === 0 ) {
 						$found_prefix = $prefix;
 						break;
 					}
@@ -177,7 +177,7 @@ protected function transform( $string, $regex, $transform_type = 'full' ) {
 			&& $string === $this->first_string
 		) {
 			if ( $this->found_prefix !== '' ) {
-				$string = substr( $string, strlen( $this->found_prefix ) );
+				$string = \substr( $string, \strlen( $this->found_prefix ) );
 			}
 
 			return $this->found_prefix . parent::transform( $string, $regex, $transform_type );
@@ -188,8 +188,8 @@ protected function transform( $string, $regex, $transform_type = 'full' ) {
 			$this->first_string = $string;
 
 			foreach ( $this->validated_prefixes as $prefix ) {
-				if ( strpos( $string, $prefix ) === 0 ) {
-					$string             = substr( $string, strlen( $prefix ) );
+				if ( \strpos( $string, $prefix ) === 0 ) {
+					$string             = \substr( $string, \strlen( $prefix ) );
 					$this->found_prefix = $prefix;
 
 					/*
@@ -229,14 +229,14 @@ public function verify_yoast_hook_name( $stackPtr, $parameters ) {
 		/*
 		 * Check that the namespace-like prefix is used for hooks.
 		 */
-		if ( strpos( $this->found_prefix, '\\' ) === false ) {
+		if ( \strpos( $this->found_prefix, '\\' ) === false ) {
 			/*
 			 * Find which namespace-based prefix should have been used.
 			 * Loop till the end as the shortest prefix will be last.
 			 */
 			$namespace_prefix = '';
 			foreach ( $this->validated_prefixes as $prefix ) {
-				if ( strpos( $prefix, '\\' ) !== false ) {
+				if ( \strpos( $prefix, '\\' ) !== false ) {
 					$namespace_prefix = $prefix;
 				}
 			}
@@ -284,10 +284,10 @@ public function verify_yoast_hook_name( $stackPtr, $parameters ) {
 		 */
 		$hook_ptr  = $first_non_empty; // If no other tokens were found, the first non empty will be the hook name.
 		$hook_name = $this->strip_quotes( $this->tokens[ $hook_ptr ]['content'] );
-		$hook_name = substr( $hook_name, strlen( $this->found_prefix ) );
+		$hook_name = \substr( $hook_name, \strlen( $this->found_prefix ) );
 
-		$parts      = explode( '_', $hook_name );
-		$part_count = count( $parts );
+		$parts      = \explode( '_', $hook_name );
+		$part_count = \count( $parts );
 
 		if ( $part_count <= $this->recommended_max_words && $part_count <= $this->max_words ) {
 			return;
diff --git a/Yoast/Sniffs/WhiteSpace/FunctionSpacingSniff.php b/Yoast/Sniffs/WhiteSpace/FunctionSpacingSniff.php
index 98906489..0f7b1b89 100644
--- a/Yoast/Sniffs/WhiteSpace/FunctionSpacingSniff.php
+++ b/Yoast/Sniffs/WhiteSpace/FunctionSpacingSniff.php
@@ -25,7 +25,7 @@ class FunctionSpacingSniff extends Squiz_FunctionSpacingSniff {
 	 *
 	 * {@internal Upstream sniff defaults to 2.}}
 	 *
-	 * @var integer
+	 * @var int
 	 */
 	public $spacing = 1;
 
@@ -34,7 +34,7 @@ class FunctionSpacingSniff extends Squiz_FunctionSpacingSniff {
 	 *
 	 * {@internal Upstream sniff defaults to 2.}}
 	 *
-	 * @var integer
+	 * @var int
 	 */
 	public $spacingBeforeFirst = 1;
 
@@ -43,7 +43,7 @@ class FunctionSpacingSniff extends Squiz_FunctionSpacingSniff {
 	 *
 	 * {@internal Upstream sniff defaults to 2.}}
 	 *
-	 * @var integer
+	 * @var int
 	 */
 	public $spacingAfterLast = 0;
 
@@ -54,11 +54,9 @@ class FunctionSpacingSniff extends Squiz_FunctionSpacingSniff {
 	 * @param int                         $stackPtr  The position of the current token
 	 *                                               in the stack passed in $tokens.
 	 *
-	 * @return void
+	 * @return void|int Optionally returns stack pointer to skip to.
 	 */
 	public function process( File $phpcsFile, $stackPtr ) {
-		$tokens = $phpcsFile->getTokens();
-
 		// Check that the function is nested in an OO structure (class, trait, interface).
 		if ( $phpcsFile->hasCondition( $stackPtr, Tokens::$ooScopeTokens ) === false ) {
 			return;
diff --git a/Yoast/Sniffs/Yoast/AlternativeFunctionsSniff.php b/Yoast/Sniffs/Yoast/AlternativeFunctionsSniff.php
index 639aafab..ae9c198b 100644
--- a/Yoast/Sniffs/Yoast/AlternativeFunctionsSniff.php
+++ b/Yoast/Sniffs/Yoast/AlternativeFunctionsSniff.php
@@ -40,8 +40,7 @@ public function getGroups() {
 	 * @param string $group_name      The name of the group which was matched.
 	 * @param string $matched_content The token content (function name) which was matched.
 	 *
-	 * @return int|void Integer stack pointer to skip forward or void to continue
-	 *                  normal file processing.
+	 * @return void
 	 */
 	public function process_matched_token( $stackPtr, $group_name, $matched_content ) {
 
diff --git a/Yoast/Tests/Files/FileNameUnitTest.php b/Yoast/Tests/Files/FileNameUnitTest.php
index b76ad069..7c205117 100644
--- a/Yoast/Tests/Files/FileNameUnitTest.php
+++ b/Yoast/Tests/Files/FileNameUnitTest.php
@@ -18,7 +18,7 @@ class FileNameUnitTest extends AbstractSniffUnitTest {
 	/**
 	 * Error files with the expected nr of errors.
 	 *
-	 * @var array
+	 * @var int[]
 	 */
 	private $expected_results = [
 
@@ -89,7 +89,7 @@ public function setCliValues( $testFile, $config ) {
 			return;
 		}
 
-		$config->basepath = __DIR__ . DIRECTORY_SEPARATOR . 'FileNameUnitTests';
+		$config->basepath = __DIR__ . \DIRECTORY_SEPARATOR . 'FileNameUnitTests';
 	}
 
 	/**
@@ -100,8 +100,8 @@ public function setCliValues( $testFile, $config ) {
 	 * @return string[]
 	 */
 	protected function getTestFiles( $testFileBase ) {
-		$sep        = DIRECTORY_SEPARATOR;
-		$test_files = glob( dirname( $testFileBase ) . $sep . 'FileNameUnitTests{' . $sep . ',' . $sep . '*' . $sep . '}*.inc', GLOB_BRACE );
+		$sep        = \DIRECTORY_SEPARATOR;
+		$test_files = \glob( \dirname( $testFileBase ) . $sep . 'FileNameUnitTests{' . $sep . ',' . $sep . '*' . $sep . '}*.inc', \GLOB_BRACE );
 
 		if ( ! empty( $test_files ) ) {
 			return $test_files;
diff --git a/Yoast/Tests/Files/TestDoublesUnitTest.php b/Yoast/Tests/Files/TestDoublesUnitTest.php
index 25fdd3ff..6feffbf6 100644
--- a/Yoast/Tests/Files/TestDoublesUnitTest.php
+++ b/Yoast/Tests/Files/TestDoublesUnitTest.php
@@ -28,7 +28,7 @@ public function setCliValues( $testFile, $config ) {
 			return;
 		}
 
-		$config->basepath = __DIR__ . DIRECTORY_SEPARATOR . 'TestDoublesUnitTests';
+		$config->basepath = __DIR__ . \DIRECTORY_SEPARATOR . 'TestDoublesUnitTests';
 	}
 
 	/**
@@ -39,8 +39,8 @@ public function setCliValues( $testFile, $config ) {
 	 * @return string[]
 	 */
 	protected function getTestFiles( $testFileBase ) {
-		$sep        = DIRECTORY_SEPARATOR;
-		$test_files = glob( dirname( $testFileBase ) . $sep . 'TestDoublesUnitTests{' . $sep . ',' . $sep . '*' . $sep . '}*.inc', GLOB_BRACE );
+		$sep        = \DIRECTORY_SEPARATOR;
+		$test_files = \glob( \dirname( $testFileBase ) . $sep . 'TestDoublesUnitTests{' . $sep . ',' . $sep . '*' . $sep . '}*.inc', \GLOB_BRACE );
 
 		if ( ! empty( $test_files ) ) {
 			return $test_files;
diff --git a/Yoast/Tests/NamingConventions/NamespaceNameUnitTest.php b/Yoast/Tests/NamingConventions/NamespaceNameUnitTest.php
index 20a1e79a..e4e7220f 100644
--- a/Yoast/Tests/NamingConventions/NamespaceNameUnitTest.php
+++ b/Yoast/Tests/NamingConventions/NamespaceNameUnitTest.php
@@ -25,11 +25,11 @@ class NamespaceNameUnitTest extends AbstractSniffUnitTest {
 	 * @return void
 	 */
 	public function setCliValues( $testFile, $config ) {
-		if ( strpos( $testFile, 'no-basepath' ) === 0 ) {
+		if ( \strpos( $testFile, 'no-basepath' ) === 0 ) {
 			return;
 		}
 
-		$config->basepath = __DIR__ . DIRECTORY_SEPARATOR . 'NamespaceNameUnitTests';
+		$config->basepath = __DIR__ . \DIRECTORY_SEPARATOR . 'NamespaceNameUnitTests';
 	}
 
 	/**
@@ -40,8 +40,8 @@ public function setCliValues( $testFile, $config ) {
 	 * @return string[]
 	 */
 	protected function getTestFiles( $testFileBase ) {
-		$sep        = DIRECTORY_SEPARATOR;
-		$test_files = glob( dirname( $testFileBase ) . $sep . 'NamespaceNameUnitTests{' . $sep . ',' . $sep . '*' . $sep . '}*.inc', GLOB_BRACE );
+		$sep        = \DIRECTORY_SEPARATOR;
+		$test_files = \glob( \dirname( $testFileBase ) . $sep . 'NamespaceNameUnitTests{' . $sep . ',' . $sep . '*' . $sep . '}*.inc', \GLOB_BRACE );
 
 		if ( ! empty( $test_files ) ) {
 			return $test_files;
diff --git a/Yoast/Tests/NamingConventions/NamespaceNameUnitTests/live-coding.inc b/Yoast/Tests/NamingConventions/NamespaceNameUnitTests/live-coding.inc
new file mode 100644
index 00000000..24ebec1e
--- /dev/null
+++ b/Yoast/Tests/NamingConventions/NamespaceNameUnitTests/live-coding.inc
@@ -0,0 +1,7 @@
+<?php
+
+/*
+ * Test sniff behaviour during live coding.
+ */
+
+namespace Foo
diff --git a/Yoast/Utils/CustomPrefixesTrait.php b/Yoast/Utils/CustomPrefixesTrait.php
index 3124667b..6b54fa07 100644
--- a/Yoast/Utils/CustomPrefixesTrait.php
+++ b/Yoast/Utils/CustomPrefixesTrait.php
@@ -64,7 +64,7 @@ protected function validate_prefixes() {
 		$this->previous_prefixes = $this->prefixes;
 
 		$prefixes = (array) $this->prefixes;
-		$prefixes = array_filter( array_map( 'trim', $prefixes ) );
+		$prefixes = \array_filter( \array_map( 'trim', $prefixes ) );
 
 		if ( empty( $prefixes ) ) {
 			$this->validated_prefixes = [];
@@ -76,19 +76,19 @@ protected function validate_prefixes() {
 
 		$validated = [];
 		foreach ( $prefixes as $prefix ) {
-			if ( strpos( $prefix, '\\' ) !== false ) {
-				$prefix      = trim( $prefix, '\\' );
+			if ( \strpos( $prefix, '\\' ) !== false ) {
+				$prefix      = \trim( $prefix, '\\' );
 				$validated[] = $prefix . '\\';
 			}
 			else {
 				// Old-style prefix.
-				$prefix      = trim( $prefix, '_' );
+				$prefix      = \trim( $prefix, '_' );
 				$validated[] = $prefix . '_';
 			}
 		}
 
 		// Use reverse natural sorting to get the longest prefix first.
-		rsort( $validated, ( SORT_NATURAL | SORT_FLAG_CASE ) );
+		\rsort( $validated, ( \SORT_NATURAL | \SORT_FLAG_CASE ) );
 
 		// Set the validated prefixes cache.
 		$this->validated_prefixes = $validated;
@@ -97,9 +97,9 @@ protected function validate_prefixes() {
 	/**
 	 * Overloadable method to do custom prefix filtering prior to validation.
 	 *
-	 * @param array $prefixes The unvalidated prefixes.
+	 * @param string[] $prefixes The unvalidated prefixes.
 	 *
-	 * @return array
+	 * @return string[]
 	 */
 	protected function filter_prefixes( $prefixes ) {
 		return $prefixes;
@@ -108,14 +108,14 @@ protected function filter_prefixes( $prefixes ) {
 	/**
 	 * Filter out all prefixes which don't contain a namespace separator.
 	 *
-	 * @param array $prefixes The unvalidated prefixes.
+	 * @param string[] $prefixes The unvalidated prefixes.
 	 *
-	 * @return array
+	 * @return string[]
 	 */
 	protected function filter_allow_only_namespace_prefixes( $prefixes ) {
 		$filtered = [];
 		foreach ( $prefixes as $prefix ) {
-			if ( strpos( $prefix, '\\' ) === false ) {
+			if ( \strpos( $prefix, '\\' ) === false ) {
 				continue;
 			}
 
@@ -128,14 +128,14 @@ protected function filter_allow_only_namespace_prefixes( $prefixes ) {
 	/**
 	 * Filter out all prefixes which only contain lowercase characters.
 	 *
-	 * @param array $prefixes The unvalidated prefixes.
+	 * @param string[] $prefixes The unvalidated prefixes.
 	 *
-	 * @return array
+	 * @return string[]
 	 */
 	protected function filter_exclude_lowercase_prefixes( $prefixes ) {
 		$filtered = [];
 		foreach ( $prefixes as $prefix ) {
-			if ( strtolower( $prefix ) === $prefix ) {
+			if ( \strtolower( $prefix ) === $prefix ) {
 				continue;
 			}
 
diff --git a/composer.json b/composer.json
index 91860281..701362c6 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,7 @@
 		"squizlabs/php_codesniffer": "^3.5.0",
 		"wp-coding-standards/wpcs": "^2.2.0",
 		"phpcompatibility/phpcompatibility-wp": "^2.1.0",
-		"dealerdirect/phpcodesniffer-composer-installer": "^0.5.0"
+		"dealerdirect/phpcodesniffer-composer-installer": "^0.5 || ^0.6"
 	},
 	"require-dev": {
 		"phpcompatibility/php-compatibility": "^9.2.0",