1 files changed, 85 insertions, 0 deletions
diff --git a/src/cmd/go/internal/test/cover.go b/src/cmd/go/internal/test/cover.go
new file mode 100644
index 0000000..f614458
--- /dev/null
+++ b/src/cmd/go/internal/test/cover.go
@@ -0,0 +1,85 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package test
+
+import (
+	"cmd/go/internal/base"
+	"cmd/go/internal/cfg"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+var coverMerge struct {
+	f          *os.File
+	sync.Mutex // for f.Write
+}
+
+// initCoverProfile initializes the test coverage profile.
+// It must be run before any calls to mergeCoverProfile or closeCoverProfile.
+// Using this function clears the profile in case it existed from a previous run,
+// or in case it doesn't exist and the test is going to fail to create it (or not run).
+func initCoverProfile() {
+	if testCoverProfile == "" || testC {
+		return
+	}
+	if !filepath.IsAbs(testCoverProfile) {
+		testCoverProfile = filepath.Join(testOutputDir.getAbs(), testCoverProfile)
+	}
+
+	// No mutex - caller's responsibility to call with no racing goroutines.
+	f, err := os.Create(testCoverProfile)
+	if err != nil {
+		base.Fatalf("%v", err)
+	}
+	_, err = fmt.Fprintf(f, "mode: %s\n", cfg.BuildCoverMode)
+	if err != nil {
+		base.Fatalf("%v", err)
+	}
+	coverMerge.f = f
+}
+
+// mergeCoverProfile merges file into the profile stored in testCoverProfile.
+// It prints any errors it encounters to ew.
+func mergeCoverProfile(ew io.Writer, file string) {
+	if coverMerge.f == nil {
+		return
+	}
+	coverMerge.Lock()
+	defer coverMerge.Unlock()
+
+	expect := fmt.Sprintf("mode: %s\n", cfg.BuildCoverMode)
+	buf := make([]byte, len(expect))
+	r, err := os.Open(file)
+	if err != nil {
+		// Test did not create profile, which is OK.
+		return
+	}
+	defer r.Close()
+
+	n, err := io.ReadFull(r, buf)
+	if n == 0 {
+		return
+	}
+	if err != nil || string(buf) != expect {
+		fmt.Fprintf(ew, "error: test wrote malformed coverage profile %s.\n", file)
+		return
+	}
+	_, err = io.Copy(coverMerge.f, r)
+	if err != nil {
+		fmt.Fprintf(ew, "error: saving coverage profile: %v\n", err)
+	}
+}
+
+func closeCoverProfile() {
+	if coverMerge.f == nil {
+		return
+	}
+	if err := coverMerge.f.Close(); err != nil {
+		base.Errorf("closing coverage profile: %v", err)
+	}
+}