merge coverprofiles instead of overwriting them

go.mod

@@ -1,8 +1,8 @@
 module github.com/Songmu/gotesplit
 
-go 1.21
+go 1.23
 
 require (
-	github.com/jstemmer/go-junit-report/v2 v2.0.0
-	golang.org/x/sync v0.3.0
+	github.com/jstemmer/go-junit-report/v2 v2.1.0
+	golang.org/x/sync v0.8.0
 )

go.sum

@@ -1,6 +1,6 @@
 github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
 github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
-github.com/jstemmer/go-junit-report/v2 v2.0.0 h1:bMZNO9B16VFn07tKyi4YJFIbZtVmJaa5Xakv9dcwK58=
-github.com/jstemmer/go-junit-report/v2 v2.0.0/go.mod h1:mgHVr7VUo5Tn8OLVr1cKnLuEy0M92wdRntM99h7RkgQ=
-golang.org/x/sync v0.3.0 h1:ftCYgMx6zT/asHUrPw8BLLscYtGznsLAnjq5RH9P66E=
-golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
+github.com/jstemmer/go-junit-report/v2 v2.1.0 h1:X3+hPYlSczH9IMIpSC9CQSZA0L+BipYafciZUWHEmsc=
+github.com/jstemmer/go-junit-report/v2 v2.1.0/go.mod h1:mgHVr7VUo5Tn8OLVr1cKnLuEy0M92wdRntM99h7RkgQ=
+golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
+golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=

gotesplit.go

@@ -40,6 +40,7 @@ Options:
 	total := fs.Uint("total", 1, "total number of test splits (CIRCLE_NODE_TOTAL is used if set)")
 	index := fs.Uint("index", 0, "zero-based index number of test splits (CIRCLE_NODE_INDEX is used if set)")
 	junitDir := fs.String("junit-dir", "", "directory to store test result in JUnit format")
+	coverprofileDir := fs.String("coverprofile-dir", ".cover", "temporary directory for collecting coverprofile")
 	fs.VisitAll(func(f *flag.Flag) {
 		if f.Name == "index" || f.Name == "total" {
 			if s := os.Getenv("CIRCLE_NODE_" + strings.ToUpper(f.Name)); s != "" {
@@ -57,7 +58,7 @@ Options:
 			return rnr.run(ctx, argv[1:], outStream, errStream)
 		}
 	}
-	return run(ctx, *total, *index, *junitDir, argv, outStream, errStream)
+	return run(ctx, *total, *index, *junitDir, *coverprofileDir, argv, outStream, errStream)
 }
 
 func getTestListsFromPkgs(pkgs []string, tags string, withRace bool) ([]testList, error) {

run.go

@@ -12,6 +12,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"github.com/jstemmer/go-junit-report/v2/gtr"
@@ -20,7 +21,7 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
-func run(ctx context.Context, total, idx uint, junitDir string, argv []string, outStream io.Writer, errStream io.Writer) error {
+func run(_ context.Context, total, idx uint, junitDir string, coverprofilesDir string, argv []string, outStream io.Writer, errStream io.Writer) error {
 	if idx >= total {
 		return fmt.Errorf("`index` should be the range from 0 to `total`-1, but: %d (total:%d)", idx, total)
 	}
@@ -111,6 +112,28 @@ func run(ctx context.Context, total, idx uint, junitDir string, argv []string, o
 		}
 	}
 
+	// Check if coverprofile flag is set. If so remove it from args and replace it
+	// later with separate coverprofile files for each `go test` run.
+	coverprofileFile := ""
+	for i := range testOpts {
+		if strings.HasPrefix(testOpts[i], "-coverprofile=") {
+			coverprofileFile = strings.TrimPrefix(testOpts[i], "-coverprofile=")
+
+			if i == len(testOpts)-1 {
+				testOpts = testOpts[:i]
+			} else {
+				testOpts = append(testOpts[:i], testOpts[i+1:]...)
+			}
+			break
+		}
+	}
+	if coverprofileFile != "" {
+		// Make temporary directory to store single coverprofile files in.
+		if err := os.MkdirAll(coverprofilesDir, 0755); err != nil {
+			return err
+		}
+	}
+
 	var testArgsList [][]string
 
 	if len(allPkgs) > 0 {
@@ -126,6 +149,11 @@ func run(ctx context.Context, total, idx uint, junitDir string, argv []string, o
 	}
 
 	for i, args := range testArgsList {
+		if coverprofileFile != "" {
+			// Write coverprofiles to temp folder.
+			args = append(args, fmt.Sprintf("-coverprofile=%s/coverprofile_%d", coverprofilesDir, i))
+		}
+
 		report := goTest(args, outStream, errStream, junitDir)
 		if err2 := report.err; err2 != nil {
 			err = err2
@@ -147,7 +175,50 @@ func run(ctx context.Context, total, idx uint, junitDir string, argv []string, o
 			}
 		}
 	}
-	return err
+	if err != nil {
+		return err
+	}
+
+	if coverprofileFile != "" {
+		// Merge single coverprofiles to one file.
+		err = mergeCoverprofiles(coverprofilesDir, coverprofileFile)
+		if err != nil {
+			return err
+		}
+
+		// Remove temp directory.
+		err = os.RemoveAll(coverprofilesDir)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func mergeCoverprofiles(dir string, coverprofileOut string) error {
+	files, err := os.ReadDir(dir)
+	if err != nil {
+		return err
+	}
+
+	modeRegex := regexp.MustCompile(`^mode: [a-zA-Z]+\n`)
+	mergedContent := []byte{}
+	for i, file := range files {
+		content, err := os.ReadFile(dir + "/" + file.Name())
+		if err != nil {
+			return fmt.Errorf("failed to read file %s: %w", file.Name(), err)
+		}
+
+		if i != 0 {
+			// Cover mode is set in first line, remove it from all the following
+			// files.
+			content = modeRegex.ReplaceAll(content, []byte{})
+		}
+		mergedContent = append(mergedContent, content...)
+	}
+
+	return os.WriteFile(coverprofileOut, mergedContent, 0755)
 }
 
 type junitReport struct {