check number of results

checker/generator/generator.go

@@ -2,7 +2,6 @@ package generator
 
 import (
 	"io"
-	"os"
 	"slices"
 	"strings"
 
@@ -15,13 +14,7 @@ type MessageGenerator interface {
 
 type Getter func() (MessageGenerator, error)
 
-func Generate(getter Getter) error {
-	out, err := os.Create("messages.yaml")
-	if err != nil {
-		return err
-	}
-	defer out.Close()
-
+func Generate(getter Getter, out io.Writer) error {
 	data, err := getter()
 	if err != nil {
 		return err

checker/generator/generator_test.go

@@ -1,16 +1,46 @@
 package generator_test
 
 import (
+	"bytes"
+	"io"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/require"
 	"github.com/tufin/oasdiff/checker/generator"
 )
 
 func TestGenerator(t *testing.T) {
-	require.NoError(t, generator.Generate(generator.GetAll))
+	out, err := os.Create("messages.yaml")
+	require.NoError(t, err)
+	defer out.Close()
+
+	require.NoError(t, generator.Generate(generator.GetAll, out))
 }
 
 func TestTreeGenerator(t *testing.T) {
-	require.NoError(t, generator.Generate(generator.GetTree("tree.yaml")))
+	var out bytes.Buffer
+	require.NoError(t, generator.Generate(generator.GetTree("tree.yaml"), &out))
+	count, err := lineCounter(&out)
+	require.NoError(t, err)
+	require.Equal(t, 176, count)
+}
+
+func lineCounter(r io.Reader) (int, error) {
+	buf := make([]byte, 32*1024)
+	count := 0
+	lineSep := []byte{'\n'}
+
+	for {
+		c, err := r.Read(buf)
+		count += bytes.Count(buf[:c], lineSep)
+
+		switch {
+		case err == io.EOF:
+			return count, nil
+
+		case err != nil:
+			return count, err
+		}
+	}
 }