From 3615eb16af57b832a3b6d957d86b84b656865a14 Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <iant@golang.org>
Date: Thu, 3 Nov 2022 13:22:37 -0700
Subject: [PATCH] testing: add Get method for -test.v option

There is existing code that calls flag.Lookup("test.v") and inspects
the value. That stopped working as of CL 443596. Make code like that
continue to work at least for the case where we aren't using
-test.v=test2json.

Change-Id: Idb30b149b48ee3987a201e349cf4d9bfe9ddee56
Reviewed-on: https://go-review.googlesource.com/c/go/+/447796
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
---
 src/testing/flag_test.go | 86 ++++++++++++++++++++++++++++++++++++++++
 src/testing/testing.go   |  7 ++++
 2 files changed, 93 insertions(+)
 create mode 100644 src/testing/flag_test.go

diff --git a/src/testing/flag_test.go b/src/testing/flag_test.go
new file mode 100644
index 0000000000..483ae6530d
--- /dev/null
+++ b/src/testing/flag_test.go
@@ -0,0 +1,86 @@
+// 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 testing_test
+
+import (
+	"flag"
+	"internal/testenv"
+	"os"
+	"os/exec"
+	"testing"
+)
+
+var testFlagArg = flag.String("test_flag_arg", "", "TestFlag: passing -v option")
+
+const flagTestEnv = "GO_WANT_FLAG_HELPER_PROCESS"
+
+func TestFlag(t *testing.T) {
+	if os.Getenv(flagTestEnv) == "1" {
+		testFlagHelper(t)
+		return
+	}
+
+	testenv.MustHaveExec(t)
+
+	for _, flag := range []string{"", "-test.v", "-test.v=test2json"} {
+		flag := flag
+		t.Run(flag, func(t *testing.T) {
+			t.Parallel()
+			exe, err := os.Executable()
+			if err != nil {
+				exe = os.Args[0]
+			}
+			cmd := exec.Command(exe, "-test.run=TestFlag", "-test_flag_arg="+flag)
+			if flag != "" {
+				cmd.Args = append(cmd.Args, flag)
+			}
+			cmd.Env = append(cmd.Environ(), flagTestEnv+"=1")
+			b, err := cmd.CombinedOutput()
+			if len(b) > 0 {
+				t.Logf("%s", b)
+			}
+			if err != nil {
+				t.Error(err)
+			}
+		})
+	}
+}
+
+// testFlagHelper is called by the TestFlagHelper subprocess.
+func testFlagHelper(t *testing.T) {
+	f := flag.Lookup("test.v")
+	if f == nil {
+		t.Fatal(`flag.Lookup("test.v") failed`)
+	}
+
+	bf, ok := f.Value.(interface{ IsBoolFlag() bool })
+	if !ok {
+		t.Errorf("test.v flag (type %T) does not have IsBoolFlag method", f)
+	} else if !bf.IsBoolFlag() {
+		t.Error("test.v IsBoolFlag() returned false")
+	}
+
+	gf, ok := f.Value.(flag.Getter)
+	if !ok {
+		t.Fatalf("test.v flag (type %T) does not have Get method", f)
+	}
+	v := gf.Get()
+
+	var want any
+	switch *testFlagArg {
+	case "":
+		want = false
+	case "-test.v":
+		want = true
+	case "-test.v=test2json":
+		want = "test2json"
+	default:
+		t.Fatalf("unexpected test_flag_arg %q", *testFlagArg)
+	}
+
+	if v != want {
+		t.Errorf("test.v is %v want %v", v, want)
+	}
+}
diff --git a/src/testing/testing.go b/src/testing/testing.go
index e694b6cb6b..b2a65e95d3 100644
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -513,6 +513,13 @@ func (f *chattyFlag) String() string {
 	return "false"
 }
 
+func (f *chattyFlag) Get() any {
+	if f.json {
+		return "test2json"
+	}
+	return f.on
+}
+
 const marker = byte(0x16) // ^V for framing
 
 func (f *chattyFlag) prefix() string {
-- 
2.50.0