all: fix x/tools tests that fail with a go1.23.1 go.work file

Delete or selectively skip tests that made either of the following
assumptions:
- The default GODEBUG is that of Go 1.22 (not true given a go.work
  file).
- GOROOT is a development version of Go (not true if GOROOT is prepared
  by cmd/distpack).

Fixes golang/go#70081
Fixes golang/go#70082

Change-Id: I47dfb225427f75e3be833eed3ba677ff454935f1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/622896
Reviewed-by: Alan Donovan <adonovan@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

cmd/godoc/godoc_test.go

@@ -197,11 +197,11 @@ func TestWebIndex(t *testing.T) {
 
 // Basic integration test for godoc HTTP interface.
 func testWeb(t *testing.T, x packagestest.Exporter, bin string, withIndex bool) {
+	testenv.NeedsGOROOTDir(t, "api")
+
 	switch runtime.GOOS {
 	case "plan9":
 		t.Skip("skipping on plan9: fails to start up quickly enough")
-	case "android", "ios":
-		t.Skip("skipping on mobile: lacks GOROOT/api in test environment")
 	}
 
 	// Write a fake GOROOT/GOPATH with some third party packages.

go/ssa/builder_test.go

@@ -666,6 +666,8 @@ var indirect = R[int].M
 // TestTypeparamTest builds SSA over compilable examples in $GOROOT/test/typeparam/*.go.
 
 func TestTypeparamTest(t *testing.T) {
+	testenv.NeedsGOROOTDir(t, "test")
+
 	// Tests use a fake goroot to stub out standard libraries with declarations in
 	// testdata/src. Decreases runtime from ~80s to ~1s.
 

go/ssa/interp/interp_test.go

@@ -340,6 +340,8 @@ func TestTestdataFiles(t *testing.T) {
 
 // TestGorootTest runs the interpreter on $GOROOT/test/*.go.
 func TestGorootTest(t *testing.T) {
+	testenv.NeedsGOROOTDir(t, "test")
+
 	goroot := makeGoroot(t)
 	for _, input := range gorootTestTests {
 		t.Run(input, func(t *testing.T) {
@@ -352,6 +354,8 @@ func TestGorootTest(t *testing.T) {
 // in $GOROOT/test/typeparam/*.go.
 
 func TestTypeparamTest(t *testing.T) {
+	testenv.NeedsGOROOTDir(t, "test")
+
 	if runtime.GOARCH == "wasm" {
 		// See ssa/TestTypeparamTest.
 		t.Skip("Consistent flakes on wasm (e.g. https://go.dev/issues/64726)")

godoc/versions_test.go

@@ -7,6 +7,8 @@ package godoc
 import (
 	"go/build"
 	"testing"
+
+	"golang.org/x/tools/internal/testenv"
 )
 
 func TestParseVersionRow(t *testing.T) {
@@ -88,6 +90,8 @@ func hasTag(t string) bool {
 }
 
 func TestAPIVersion(t *testing.T) {
+	testenv.NeedsGOROOTDir(t, "api")
+
 	av, err := parsePackageAPIInfo()
 	if err != nil {
 		t.Fatal(err)

internal/aliases/aliases_test.go

@@ -44,9 +44,10 @@ func TestNewAlias(t *testing.T) {
 	}
 
 	for _, godebug := range []string{
-		// The default gotypesalias value follows the x/tools/go.mod version
-		// The go.mod is at 1.22 so the default is gotypesalias=0.
-		"", // Use the default GODEBUG value (off).
+		// Note: previously there was a test case for "", which asserted on the
+		// behavior implied by the x/tools go.mod go directive. But that only works
+		// if x/tools is the main module for the test, which isn't the case when
+		// run with a go.work file, or from another module (golang/go#70082).
 		"gotypesalias=0",
 		"gotypesalias=1",
 	} {

internal/gcimporter/gcimporter_test.go

@@ -166,6 +166,7 @@ func TestImportTypeparamTests(t *testing.T) {
 	}
 
 	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache
+	testenv.NeedsGOROOTDir(t, "test")
 
 	// This package only handles gc export data.
 	if runtime.Compiler != "gc" {

internal/gcimporter/iexport_go118_test.go

@@ -98,6 +98,7 @@ func testExportSrc(t *testing.T, src []byte) {
 
 func TestIndexedImportTypeparamTests(t *testing.T) {
 	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache
+	testenv.NeedsGOROOTDir(t, "test")
 
 	testAliases(t, testIndexedImportTypeparamTests)
 }

internal/testenv/testenv.go

@@ -490,3 +490,17 @@ func NeedsGoExperiment(t testing.TB, flag string) {
 		t.Skipf("skipping test: flag %q is not set in GOEXPERIMENT=%q", flag, goexp)
 	}
 }
+
+// NeedsGOROOTDir skips the test if GOROOT/dir does not exist, and GOROOT is a
+// released version of Go (=has a VERSION file). Some GOROOT directories are
+// removed by cmd/distpack.
+//
+// See also golang/go#70081.
+func NeedsGOROOTDir(t *testing.T, dir string) {
+	gorootTest := filepath.Join(GOROOT(t), dir)
+	if _, err := os.Stat(gorootTest); os.IsNotExist(err) {
+		if _, err := os.Stat(filepath.Join(GOROOT(t), "VERSION")); err == nil {
+			t.Skipf("skipping: GOROOT/%s not present", dir)
+		}
+	}
+}