cmd/objdump: use the test binary as 'objdump' instead of rebuilding it

This not only reduces the latency of the test, but also respects
build flags like '-race' and '-cover' passed to the 'go test' command.

Change-Id: Icd22062ab75964a74d011c81ea6c99be80bece18
Reviewed-on: https://go-review.googlesource.com/c/go/+/450704
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

diff --git a/src/cmd/objdump/objdump_test.go b/src/cmd/objdump/objdump_test.go
index b747d0d542e8506b1fcbaf6620c575fe1d6d3c80..23b299a42ba915d69328f281f47418f170a8604e 100644 (file)
--- a/src/cmd/objdump/objdump_test.go
+++ b/src/cmd/objdump/objdump_test.go
@@ -16,48 +16,42 @@ import (
        "path/filepath"
        "runtime"
        "strings"
+       "sync"
        "testing"
 )
 
-var tmp, exe string // populated by buildObjdump
-
+// TestMain executes the test binary as the objdump command if
+// GO_OBJDUMPTEST_IS_OBJDUMP is set, and runs the test otherwise.
 func TestMain(m *testing.M) {
-       if !testenv.HasGoBuild() {
-               return
+       if os.Getenv("GO_OBJDUMPTEST_IS_OBJDUMP") != "" {
+               main()
+               os.Exit(0)
        }
 
-       var exitcode int
-       if err := buildObjdump(); err == nil {
-               exitcode = m.Run()
-       } else {
-               fmt.Println(err)
-               exitcode = 1
-       }
-       os.RemoveAll(tmp)
-       os.Exit(exitcode)
+       os.Setenv("GO_OBJDUMPTEST_IS_OBJDUMP", "1")
+       os.Exit(m.Run())
 }
 
-func buildObjdump() error {
-       var err error
-       tmp, err = os.MkdirTemp("", "TestObjDump")
-       if err != nil {
-               return fmt.Errorf("TempDir failed: %v", err)
-       }
+// objdumpPath returns the path to the "objdump" binary to run.
+func objdumpPath(t testing.TB) string {
+       t.Helper()
+       testenv.MustHaveExec(t)
 
-       exe = filepath.Join(tmp, "testobjdump.exe")
-       gotool, err := testenv.GoTool()
-       if err != nil {
-               return err
-       }
-       out, err := exec.Command(gotool, "build", "-o", exe, "cmd/objdump").CombinedOutput()
-       if err != nil {
-               os.RemoveAll(tmp)
-               return fmt.Errorf("go build -o %v cmd/objdump: %v\n%s", exe, err, string(out))
+       objdumpPathOnce.Do(func() {
+               objdumpExePath, objdumpPathErr = os.Executable()
+       })
+       if objdumpPathErr != nil {
+               t.Fatal(objdumpPathErr)
        }
-
-       return nil
+       return objdumpExePath
 }
 
+var (
+       objdumpPathOnce sync.Once
+       objdumpExePath  string
+       objdumpPathErr  error
+)
+
 var x86Need = []string{ // for both 386 and AMD64
        "JMP main.main(SB)",
        "CALL main.Println(SB)",
@@ -152,6 +146,7 @@ func testDisasm(t *testing.T, srcfname string, printCode bool, printGnuAsm bool,
        }
 
        hash := notsha256.Sum256([]byte(fmt.Sprintf("%v-%v-%v-%v", srcfname, flags, printCode, printGnuAsm)))
+       tmp := t.TempDir()
        hello := filepath.Join(tmp, fmt.Sprintf("hello-%x.exe", hash))
        args := []string{"build", "-o", hello}
        args = append(args, flags...)
@@ -226,7 +221,7 @@ func testDisasm(t *testing.T, srcfname string, printCode bool, printGnuAsm bool,
        if printGnuAsm {
                args = append([]string{"-gnu"}, args...)
        }
-       cmd = exec.Command(exe, args...)
+       cmd = exec.Command(objdumpPath(t), args...)
        cmd.Dir = "testdata" // "Bad line" bug #36683 is sensitive to being run in the source directory
        out, err = cmd.CombinedOutput()
        t.Logf("Running %v", cmd.Args)
@@ -300,6 +295,9 @@ func TestDisasmPIE(t *testing.T) {
 
 func TestDisasmGoobj(t *testing.T) {
        mustHaveDisasm(t)
+       testenv.MustHaveGoBuild(t)
+
+       tmp := t.TempDir()
 
        importcfgfile := filepath.Join(tmp, "hello.importcfg")
        testenv.WriteImportcfg(t, importcfgfile, nil)
@@ -321,7 +319,7 @@ func TestDisasmGoobj(t *testing.T) {
                hello,
        }
 
-       out, err = exec.Command(exe, args...).CombinedOutput()
+       out, err = exec.Command(objdumpPath(t), args...).CombinedOutput()
        if err != nil {
                t.Fatalf("objdump fmthello.o: %v\n%s", err, out)
        }
@@ -352,13 +350,9 @@ func TestGoobjFileNumber(t *testing.T) {
 
        t.Parallel()
 
-       tmpdir, err := os.MkdirTemp("", "TestGoobjFileNumber")
-       if err != nil {
-               t.Fatal(err)
-       }
-       defer os.RemoveAll(tmpdir)
+       tmp := t.TempDir()
 
-       obj := filepath.Join(tmpdir, "p.a")
+       obj := filepath.Join(tmp, "p.a")
        cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", obj)
        cmd.Dir = filepath.Join("testdata/testfilenum")
        out, err := cmd.CombinedOutput()
@@ -366,7 +360,7 @@ func TestGoobjFileNumber(t *testing.T) {
                t.Fatalf("build failed: %v\n%s", err, out)
        }
 
-       cmd = exec.Command(exe, obj)
+       cmd = exec.Command(objdumpPath(t), obj)
        out, err = cmd.CombinedOutput()
        if err != nil {
                t.Fatalf("objdump failed: %v\n%s", err, out)
@@ -389,7 +383,7 @@ func TestGoObjOtherVersion(t *testing.T) {
        t.Parallel()
 
        obj := filepath.Join("testdata", "go116.o")
-       cmd := exec.Command(exe, obj)
+       cmd := exec.Command(objdumpPath(t), obj)
        out, err := cmd.CombinedOutput()
        if err == nil {
                t.Fatalf("objdump go116.o succeeded unexpectedly")