runtime/coverage: improve unit tests

Add a testpoint to cover support routines used to help
implement "go test -cover".

Change-Id: Ic28bf884a4e0d2c0a6d8fd04fc29c0c949227f21
Reviewed-on: https://go-review.googlesource.com/c/go/+/432315
Reviewed-by: Bryan Mills <bcmills@google.com>

diff --git a/src/runtime/coverage/testsupport.go b/src/runtime/coverage/testsupport.go
index 0d0605c0f2f6cf69da3ad7c945013f507dd7debf..462d06c878fe1a85590e2d6be51db2b101785686 100644 (file)
--- a/src/runtime/coverage/testsupport.go
+++ b/src/runtime/coverage/testsupport.go
@@ -13,6 +13,7 @@ import (
        "internal/coverage/decodecounter"
        "internal/coverage/decodemeta"
        "internal/coverage/pods"
+       "io"
        "os"
 )
 
@@ -21,6 +22,12 @@ import (
 // intended to be used other than internally by the Go command's
 // generated code.
 func processCoverTestDir(dir string, cfile string, cm string, cpkg string) error {
+       return processCoverTestDirInternal(dir, cfile, cm, cpkg, os.Stdout)
+}
+
+// processCoverTestDirInternal is an io.Writer version of processCoverTestDir,
+// exposed for unit testing.
+func processCoverTestDirInternal(dir string, cfile string, cm string, cpkg string, w io.Writer) error {
        cmode := coverage.ParseCounterMode(cm)
        if cmode == coverage.CtrModeInvalid {
                return fmt.Errorf("invalid counter mode %q", cm)
@@ -80,7 +87,7 @@ func processCoverTestDir(dir string, cfile string, cm string, cpkg string) error
        }
 
        // Emit percent.
-       if err := ts.cf.EmitPercent(os.Stdout, cpkg, true); err != nil {
+       if err := ts.cf.EmitPercent(w, cpkg, true); err != nil {
                return err
        }
 

diff --git a/src/runtime/coverage/ts_test.go b/src/runtime/coverage/ts_test.go
new file mode 100644 (file)
index 0000000..b826058
--- /dev/null
+++ b/src/runtime/coverage/ts_test.go
@@ -0,0 +1,58 @@
+// Copyright 2022 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 coverage
+
+import (
+       "internal/goexperiment"
+       "os"
+       "path/filepath"
+       "strings"
+       "testing"
+       _ "unsafe"
+)
+
+//go:linkname testing_testGoCoverDir testing.testGoCoverDir
+func testing_testGoCoverDir() string
+
+// TestTestSupport does a basic verification of the functionality in
+// runtime/coverage.processCoverTestDir (doing this here as opposed to
+// relying on other test paths will provide a better signal when
+// running "go test -cover" for this package).
+func TestTestSupport(t *testing.T) {
+       if !goexperiment.CoverageRedesign {
+               return
+       }
+       if testing.CoverMode() == "" {
+               return
+       }
+       t.Logf("testing.testGoCoverDir() returns %s mode=%s\n",
+               testing_testGoCoverDir(), testing.CoverMode())
+
+       textfile := filepath.Join(t.TempDir(), "file.txt")
+       var sb strings.Builder
+       err := processCoverTestDirInternal(testing_testGoCoverDir(), textfile,
+               testing.CoverMode(), "", &sb)
+       if err != nil {
+               t.Fatalf("bad: %v", err)
+       }
+
+       // Check for existence of text file.
+       if inf, err := os.Open(textfile); err != nil {
+               t.Fatalf("problems opening text file %s: %v", textfile, err)
+       } else {
+               inf.Close()
+       }
+
+       // Check for percent output with expected tokens.
+       strout := sb.String()
+       want1 := "runtime/coverage"
+       want2 := "of statements"
+       if !strings.Contains(strout, want1) ||
+               !strings.Contains(strout, want2) {
+               t.Logf("output from run: %s\n", strout)
+               t.Fatalf("percent output missing key tokens: %q and %q",
+                       want1, want2)
+       }
+}

diff --git a/src/testing/newcover.go b/src/testing/newcover.go
index e90b9c980504bb42f00afad06a3b2c67ec5c8b33..1805f791e63dec7f23ae15c1aed9f4ee9fffb309 100644 (file)
--- a/src/testing/newcover.go
+++ b/src/testing/newcover.go
@@ -39,3 +39,10 @@ func coverReport2() {
                os.Exit(2)
        }
 }
+
+// testGoCoverDir returns the value passed to the -test.gocoverdir
+// flag by the Go command, if goexperiment.CoverageRedesign is
+// in effect.
+func testGoCoverDir() string {
+       return *gocoverdir
+}