cmd/cgo/internal: skip in tests, not in TestMain

Many cgo integration tests do a lot of common setup in TestMain, and
that means they require a lot from the test environment to even get
off the ground. If something is missing, right now they print a "SKIP"
message to stderr and exit without running any tests.

Make these behave more like normal tests by instead setting a global
skip function if some precondition isn't satisfied, and having every
test call that. This way we run the tests and see them skip.

I would prefer something much more structured. For example, if we
replaced the global state set up by TestMain in these tests by instead
calling a function that returned that state (after setting it up on
the first call), that function could do the appropriate skips and
there would be no way to accidentally access this state without
checking the preconditions. But that's substantially more work and may
be much easier after we do further cleanup of these tests.

Change-Id: I92de569fd27596798c5e478402449cd735ec53a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/497096
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>

1 files changed, 31 insertions, 10 deletions

diff --git a/src/cmd/cgo/internal/testplugin/plugin_test.go b/src/cmd/cgo/internal/testplugin/plugin_test.go
index 4c8e3d7833..542ee2d460 100644
--- a/src/cmd/cgo/internal/testplugin/plugin_test.go
+++ b/src/cmd/cgo/internal/testplugin/plugin_test.go
@@ -22,15 +22,13 @@ import (
 	"time"
 )
 
+var globalSkip = func(t *testing.T) {}
+
 var gcflags string = os.Getenv("GO_GCFLAGS")
 var goroot string
 
 func TestMain(m *testing.M) {
 	flag.Parse()
-	if testing.Short() && os.Getenv("GO_BUILDER_NAME") == "" {
-		fmt.Printf("SKIP - short mode and $GO_BUILDER_NAME not set\n")
-		os.Exit(0)
-	}
 	log.SetFlags(log.Lshortfile)
 	os.Exit(testMain(m))
 }
@@ -48,15 +46,17 @@ func prettyPrintf(format string, args ...interface{}) {
 }
 
 func testMain(m *testing.M) int {
-	// TODO: Move all of this initialization stuff into a sync.Once that each
-	// test can use, where we can properly t.Skip.
+	if testing.Short() && os.Getenv("GO_BUILDER_NAME") == "" {
+		globalSkip = func(t *testing.T) { t.Skip("short mode and $GO_BUILDER_NAME not set") }
+		return m.Run()
+	}
 	if !platform.BuildModeSupported(runtime.Compiler, "plugin", runtime.GOOS, runtime.GOARCH) {
-		fmt.Printf("SKIP - plugin build mode not supported\n")
-		os.Exit(0)
+		globalSkip = func(t *testing.T) { t.Skip("plugin build mode not supported") }
+		return m.Run()
 	}
 	if !testenv.HasCGO() {
-		fmt.Printf("SKIP - cgo not supported\n")
-		os.Exit(0)
+		globalSkip = func(t *testing.T) { t.Skip("cgo not supported") }
+		return m.Run()
 	}
 
 	cwd, err := os.Getwd()
@@ -205,12 +205,14 @@ func run(t *testing.T, bin string, args ...string) string {
 
 func TestDWARFSections(t *testing.T) {
 	// test that DWARF sections are emitted for plugins and programs importing "plugin"
+	globalSkip(t)
 	goCmd(t, "run", "./checkdwarf/main.go", "plugin2.so", "plugin2.UnexportedNameReuse")
 	goCmd(t, "run", "./checkdwarf/main.go", "./host.exe", "main.main")
 }
 
 func TestBuildID(t *testing.T) {
 	// check that plugin has build ID.
+	globalSkip(t)
 	b := goCmd(t, "tool", "buildid", "plugin1.so")
 	if len(b) == 0 {
 		t.Errorf("build id not found")
@@ -218,10 +220,12 @@ func TestBuildID(t *testing.T) {
 }
 
 func TestRunHost(t *testing.T) {
+	globalSkip(t)
 	run(t, "./host.exe")
 }
 
 func TestUniqueTypesAndItabs(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "./iface_a")
 	goCmd(t, "build", "-buildmode=plugin", "./iface_b")
 	goCmd(t, "build", "-o", "iface.exe", "./iface")
@@ -231,6 +235,7 @@ func TestUniqueTypesAndItabs(t *testing.T) {
 func TestIssue18676(t *testing.T) {
 	// make sure we don't add the same itab twice.
 	// The buggy code hangs forever, so use a timeout to check for that.
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "plugin.so", "./issue18676/plugin.go")
 	goCmd(t, "build", "-o", "issue18676.exe", "./issue18676/main.go")
 
@@ -245,28 +250,33 @@ func TestIssue18676(t *testing.T) {
 
 func TestIssue19534(t *testing.T) {
 	// Test that we can load a plugin built in a path with non-alpha characters.
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-gcflags=-p=issue.19534", "-ldflags=-pluginpath=issue.19534", "-o", "plugin.so", "./issue19534/plugin.go")
 	goCmd(t, "build", "-o", "issue19534.exe", "./issue19534/main.go")
 	run(t, "./issue19534.exe")
 }
 
 func TestIssue18584(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "plugin.so", "./issue18584/plugin.go")
 	goCmd(t, "build", "-o", "issue18584.exe", "./issue18584/main.go")
 	run(t, "./issue18584.exe")
 }
 
 func TestIssue19418(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-ldflags=-X main.Val=linkstr", "-o", "plugin.so", "./issue19418/plugin.go")
 	goCmd(t, "build", "-o", "issue19418.exe", "./issue19418/main.go")
 	run(t, "./issue19418.exe")
 }
 
 func TestIssue19529(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "plugin.so", "./issue19529/plugin.go")
 }
 
 func TestIssue22175(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "issue22175_plugin1.so", "./issue22175/plugin1.go")
 	goCmd(t, "build", "-buildmode=plugin", "-o", "issue22175_plugin2.so", "./issue22175/plugin2.go")
 	goCmd(t, "build", "-o", "issue22175.exe", "./issue22175/main.go")
@@ -274,18 +284,21 @@ func TestIssue22175(t *testing.T) {
 }
 
 func TestIssue22295(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "issue.22295.so", "./issue22295.pkg")
 	goCmd(t, "build", "-o", "issue22295.exe", "./issue22295.pkg/main.go")
 	run(t, "./issue22295.exe")
 }
 
 func TestIssue24351(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "issue24351.so", "./issue24351/plugin.go")
 	goCmd(t, "build", "-o", "issue24351.exe", "./issue24351/main.go")
 	run(t, "./issue24351.exe")
 }
 
 func TestIssue25756(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "life.so", "./issue25756/plugin")
 	goCmd(t, "build", "-o", "issue25756.exe", "./issue25756/main.go")
 	// Fails intermittently, but 20 runs should cause the failure
@@ -299,6 +312,7 @@ func TestIssue25756(t *testing.T) {
 
 // Test with main using -buildmode=pie with plugin for issue #43228
 func TestIssue25756pie(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "life.so", "./issue25756/plugin")
 	goCmd(t, "build", "-buildmode=pie", "-o", "issue25756pie.exe", "./issue25756/main.go")
 	run(t, "./issue25756pie.exe")
@@ -306,24 +320,28 @@ func TestIssue25756pie(t *testing.T) {
 
 func TestMethod(t *testing.T) {
 	// Exported symbol's method must be live.
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "plugin.so", "./method/plugin.go")
 	goCmd(t, "build", "-o", "method.exe", "./method/main.go")
 	run(t, "./method.exe")
 }
 
 func TestMethod2(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "method2.so", "./method2/plugin.go")
 	goCmd(t, "build", "-o", "method2.exe", "./method2/main.go")
 	run(t, "./method2.exe")
 }
 
 func TestMethod3(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "method3.so", "./method3/plugin.go")
 	goCmd(t, "build", "-o", "method3.exe", "./method3/main.go")
 	run(t, "./method3.exe")
 }
 
 func TestIssue44956(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "issue44956p1.so", "./issue44956/plugin1.go")
 	goCmd(t, "build", "-buildmode=plugin", "-o", "issue44956p2.so", "./issue44956/plugin2.go")
 	goCmd(t, "build", "-o", "issue44956.exe", "./issue44956/main.go")
@@ -331,10 +349,12 @@ func TestIssue44956(t *testing.T) {
 }
 
 func TestIssue52937(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "issue52937.so", "./issue52937/main.go")
 }
 
 func TestIssue53989(t *testing.T) {
+	globalSkip(t)
 	goCmd(t, "build", "-buildmode=plugin", "-o", "issue53989.so", "./issue53989/plugin.go")
 	goCmd(t, "build", "-o", "issue53989.exe", "./issue53989/main.go")
 	run(t, "./issue53989.exe")
@@ -342,6 +362,7 @@ func TestIssue53989(t *testing.T) {
 
 func TestForkExec(t *testing.T) {
 	// Issue 38824: importing the plugin package causes it hang in forkExec on darwin.
+	globalSkip(t)
 
 	t.Parallel()
 	goCmd(t, "build", "-o", "forkexec.exe", "./forkexec/main.go")