cmd/go: roll forward "convert TestShadowingLogic to the script framework"

This rolls forward the change golang.org/cl/214431, which was reverted
in golang.org/cl/220217. The cl was broken because
TestVersionControlErrorMessageIncludesCorrectDirectory, which is going
to be removed in golang.org/cl/214429 hadn't been submitted yet.

Original change description:

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: I87b3f9acb8575fbcbd58d454b5f9bac4923429b3
Reviewed-on: https://go-review.googlesource.com/c/go/+/220178
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

src/cmd/go/go_test.go

@@ -1543,51 +1543,6 @@ func TestSymlinkWarning(t *testing.T) {
 	tg.grepStderr("ignoring symlink", "list should have reported symlink")
 }
 
-func TestShadowingLogic(t *testing.T) {
-	skipIfGccgo(t, "gccgo has no standard packages")
-	tg := testgo(t)
-	defer tg.cleanup()
-	pwd := tg.pwd()
-	sep := string(filepath.ListSeparator)
-	tg.setenv("GOPATH", filepath.Join(pwd, "testdata", "shadow", "root1")+sep+filepath.Join(pwd, "testdata", "shadow", "root2"))
-
-	// The math in root1 is not "math" because the standard math is.
-	tg.run("list", "-f", "({{.ImportPath}}) ({{.ConflictDir}})", "./testdata/shadow/root1/src/math")
-	pwdForwardSlash := strings.ReplaceAll(pwd, string(os.PathSeparator), "/")
-	if !strings.HasPrefix(pwdForwardSlash, "/") {
-		pwdForwardSlash = "/" + pwdForwardSlash
-	}
-	// The output will have makeImportValid applies, but we only
-	// bother to deal with characters we might reasonably see.
-	for _, r := range " :" {
-		pwdForwardSlash = strings.ReplaceAll(pwdForwardSlash, string(r), "_")
-	}
-	want := "(_" + pwdForwardSlash + "/testdata/shadow/root1/src/math) (" + filepath.Join(runtime.GOROOT(), "src", "math") + ")"
-	if strings.TrimSpace(tg.getStdout()) != want {
-		t.Error("shadowed math is not shadowed; looking for", want)
-	}
-
-	// The foo in root1 is "foo".
-	tg.run("list", "-f", "({{.ImportPath}}) ({{.ConflictDir}})", "./testdata/shadow/root1/src/foo")
-	if strings.TrimSpace(tg.getStdout()) != "(foo) ()" {
-		t.Error("unshadowed foo is shadowed")
-	}
-
-	// The foo in root2 is not "foo" because the foo in root1 got there first.
-	tg.run("list", "-f", "({{.ImportPath}}) ({{.ConflictDir}})", "./testdata/shadow/root2/src/foo")
-	want = "(_" + pwdForwardSlash + "/testdata/shadow/root2/src/foo) (" + filepath.Join(pwd, "testdata", "shadow", "root1", "src", "foo") + ")"
-	if strings.TrimSpace(tg.getStdout()) != want {
-		t.Error("shadowed foo is not shadowed; looking for", want)
-	}
-
-	// The error for go install should mention the conflicting directory.
-	tg.runFail("install", "./testdata/shadow/root2/src/foo")
-	want = "go install: no install location for " + filepath.Join(pwd, "testdata", "shadow", "root2", "src", "foo") + ": hidden by " + filepath.Join(pwd, "testdata", "shadow", "root1", "src", "foo")
-	if strings.TrimSpace(tg.getStderr()) != want {
-		t.Error("wrong shadowed install error; looking for", want)
-	}
-}
-
 func TestCgoDependsOnSyscall(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test that removes $GOROOT/pkg/*_race in short mode")

src/cmd/go/testdata/script/list_shadow.txt

@@ -0,0 +1,25 @@
+env GO111MODULE=off
+env GOPATH=$WORK/gopath/src/shadow/root1${:}$WORK/gopath/src/shadow/root2
+
+# The math in root1 is not "math" because the standard math is.
+go list -f '({{.ImportPath}}) ({{.ConflictDir}})' ./shadow/root1/src/math
+stdout '^\(.*(\\|/)src(\\|/)shadow(\\|/)root1(\\|/)src(\\|/)math\) \('$GOROOT'(\\|/)?src(\\|/)math\)$'
+
+# The foo in root1 is "foo".
+go list -f '({{.ImportPath}}) ({{.ConflictDir}})' ./shadow/root1/src/foo
+stdout '^\(foo\) \(\)$'
+
+# The foo in root2 is not "foo" because the foo in root1 got there first.
+go list -f '({{.ImportPath}}) ({{.ConflictDir}})' ./shadow/root2/src/foo
+stdout '^\(.*gopath(\\|/)src(\\|/)shadow(\\|/)root2(\\|/)src(\\|/)foo\) \('$WORK'(\\|/)?gopath(\\|/)src(\\|/)shadow(\\|/)root1(\\|/)src(\\|/)foo\)$'
+
+# The error for go install should mention the conflicting directory.
+! go install -n ./shadow/root2/src/foo
+stderr 'go install: no install location for '$WORK'(\\|/)?gopath(\\|/)src(\\|/)shadow(\\|/)root2(\\|/)src(\\|/)foo: hidden by '$WORK'(\\|/)?gopath(\\|/)src(\\|/)shadow(\\|/)root1(\\|/)src(\\|/)foo'
+
+-- shadow/root1/src/foo/foo.go --
+package foo
+-- shadow/root1/src/math/math.go --
+package math
+-- shadow/root2/src/foo/foo.go --
+package foo

src/cmd/go/testdata/shadow/root1/src/foo/foo.go

@@ -1 +0,0 @@
-package foo

src/cmd/go/testdata/shadow/root1/src/math/math.go

@@ -1 +0,0 @@
-package math

src/cmd/go/testdata/shadow/root2/src/foo/foo.go

@@ -1 +0,0 @@
-package foo