1 files changed, 112 insertions, 0 deletions
diff --git a/src/testing/cover.go b/src/testing/cover.go
new file mode 100644
index 000000000..a4ce37f7c
--- /dev/null
+++ b/src/testing/cover.go
@@ -0,0 +1,112 @@
+// Copyright 2013 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.
+
+// Support for test coverage.
+
+package testing
+
+import (
+	"fmt"
+	"os"
+	"sync/atomic"
+)
+
+// CoverBlock records the coverage data for a single basic block.
+// NOTE: This struct is internal to the testing infrastructure and may change.
+// It is not covered (yet) by the Go 1 compatibility guidelines.
+type CoverBlock struct {
+	Line0 uint32
+	Col0  uint16
+	Line1 uint32
+	Col1  uint16
+	Stmts uint16
+}
+
+var cover Cover
+
+// Cover records information about test coverage checking.
+// NOTE: This struct is internal to the testing infrastructure and may change.
+// It is not covered (yet) by the Go 1 compatibility guidelines.
+type Cover struct {
+	Mode            string
+	Counters        map[string][]uint32
+	Blocks          map[string][]CoverBlock
+	CoveredPackages string
+}
+
+// Coverage reports the current code coverage as a fraction in the range [0, 1].
+// If coverage is not enabled, Coverage returns 0.
+//
+// When running a large set of sequential test cases, checking Coverage after each one
+// can be useful for identifying which test cases exercise new code paths.
+// It is not a replacement for the reports generated by 'go test -cover' and
+// 'go tool cover'.
+func Coverage() float64 {
+	var n, d int64
+	for _, counters := range cover.Counters {
+		for i := range counters {
+			if atomic.LoadUint32(&counters[i]) > 0 {
+				n++
+			}
+			d++
+		}
+	}
+	if d == 0 {
+		return 0
+	}
+	return float64(n) / float64(d)
+}
+
+// RegisterCover records the coverage data accumulators for the tests.
+// NOTE: This function is internal to the testing infrastructure and may change.
+// It is not covered (yet) by the Go 1 compatibility guidelines.
+func RegisterCover(c Cover) {
+	cover = c
+}
+
+// mustBeNil checks the error and, if present, reports it and exits.
+func mustBeNil(err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "testing: %s\n", err)
+		os.Exit(2)
+	}
+}
+
+// coverReport reports the coverage percentage and writes a coverage profile if requested.
+func coverReport() {
+	var f *os.File
+	var err error
+	if *coverProfile != "" {
+		f, err = os.Create(toOutputDir(*coverProfile))
+		mustBeNil(err)
+		fmt.Fprintf(f, "mode: %s\n", cover.Mode)
+		defer func() { mustBeNil(f.Close()) }()
+	}
+
+	var active, total int64
+	var count uint32
+	for name, counts := range cover.Counters {
+		blocks := cover.Blocks[name]
+		for i := range counts {
+			stmts := int64(blocks[i].Stmts)
+			total += stmts
+			count = atomic.LoadUint32(&counts[i]) // For -mode=atomic.
+			if count > 0 {
+				active += stmts
+			}
+			if f != nil {
+				_, err := fmt.Fprintf(f, "%s:%d.%d,%d.%d %d %d\n", name,
+					blocks[i].Line0, blocks[i].Col0,
+					blocks[i].Line1, blocks[i].Col1,
+					stmts,
+					count)
+				mustBeNil(err)
+			}
+		}
+	}
+	if total == 0 {
+		total = 1
+	}
+	fmt.Printf("coverage: %.1f%% of statements%s\n", 100*float64(active)/float64(total), cover.CoveredPackages)
+}