mergedPaths doesn't modify specs (#501)

Co-authored-by: Reuven <[email protected]>

checker/composed_test.go

@@ -48,6 +48,17 @@ func TestComposed_Duplicate(t *testing.T) {
 	require.Error(t, err)
 }
 
+func TestComposed_Issue500(t *testing.T) {
+	s1 := []*load.SpecInfo{
+		loadFrom(t, "../data/composed/issue500/", 1),
+		loadFrom(t, "../data/composed/issue500/", 2),
+	}
+
+	config := diff.NewConfig()
+	_, _, err := diff.GetPathsDiff(config, s1, s1)
+	require.NoError(t, err)
+}
+
 func TestComposed_CompareMostRecent(t *testing.T) {
 	s1 := []*load.SpecInfo{
 		loadFrom(t, "../data/composed/base/", 1),

data/composed/issue500/spec1.yaml

@@ -0,0 +1,11 @@
+openapi: 3.0.3
+info:
+  title: Spec #1
+  version: "0.1"
+paths:
+  '/test':
+    get:
+      summary: GET endpoint
+      responses:
+        '200':
+          description: Success

data/composed/issue500/spec2.yaml

@@ -0,0 +1,11 @@
+openapi: 3.0.3
+info:
+  title: Spec #2
+  version: "0.1"
+paths:
+  '/test':
+    post:
+      summary: POST endpoint
+      responses:
+        '200':
+          description: Success

diff/diff.go

@@ -147,7 +147,7 @@ func mergedPaths(s1 []*load.SpecInfo, includePathParams bool) (*openapi3.Paths,
 
 			p := getPathItem(result, path, includePathParams)
 			if p == nil {
-				result.Set(path, pathItem)
+				result.Set(path, copyPathItem(pathItem))
 				for _, opItem := range pathItem.Operations() {
 					operationsSources[opItem] = s.Url
 				}
@@ -179,12 +179,31 @@ func mergedPaths(s1 []*load.SpecInfo, includePathParams bool) (*openapi3.Paths,
 					return nil, nil, fmt.Errorf("duplicate endpoint (%s %s) found in %s and %s. You may add the %s extension to specify order", op, path, operationsSources[oldOperation], s.Url, SinceDateExtension)
 				}
 			}
-
 		}
 	}
 	return result, &operationsSources, nil
 }
 
+// copyPathItem returns a shallow copy of the path item
+func copyPathItem(pathItem *openapi3.PathItem) *openapi3.PathItem {
+	return &openapi3.PathItem{
+		Extensions:  pathItem.Extensions,
+		Ref:         pathItem.Ref,
+		Summary:     pathItem.Summary,
+		Description: pathItem.Description,
+		Get:         pathItem.Get,
+		Put:         pathItem.Put,
+		Post:        pathItem.Post,
+		Delete:      pathItem.Delete,
+		Options:     pathItem.Options,
+		Head:        pathItem.Head,
+		Patch:       pathItem.Patch,
+		Trace:       pathItem.Trace,
+		Servers:     pathItem.Servers,
+		Parameters:  pathItem.Parameters,
+	}
+}
+
 func sinceDateFrom(pathItem openapi3.PathItem, operation openapi3.Operation) (civil.Date, error) {
 	since, _, err := getSinceDate(pathItem.Extensions)
 	if err != nil {