cmd/go: convert TestImportMain to a script test

Updates #28387
Updates #30316

Change-Id: I6192cc02b9e4fce3015cc47da9ec63fbea79a935
Reviewed-on: https://go-review.googlesource.com/c/go/+/207698
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/go/go_test.go

@@ -3201,95 +3201,6 @@ func TestGoGetDotSlashDownload(t *testing.T) {
 	tg.run("get", "./pprof_mac_fix")
 }
 
-// Test that you cannot import a main package.
-// See golang.org/issue/4210 and golang.org/issue/17475.
-func TestImportMain(t *testing.T) {
-	tooSlow(t)
-
-	tg := testgo(t)
-	tg.parallel()
-	defer tg.cleanup()
-
-	// Importing package main from that package main's test should work.
-	tg.tempFile("src/x/main.go", `package main
-		var X int
-		func main() {}`)
-	tg.tempFile("src/x/main_test.go", `package main_test
-		import xmain "x"
-		import "testing"
-		var _ = xmain.X
-		func TestFoo(t *testing.T) {}
-	`)
-	tg.setenv("GOPATH", tg.path("."))
-	tg.creatingTemp("x" + exeSuffix)
-	tg.run("build", "x")
-	tg.run("test", "x")
-
-	// Importing package main from another package should fail.
-	tg.tempFile("src/p1/p.go", `package p1
-		import xmain "x"
-		var _ = xmain.X
-	`)
-	tg.runFail("build", "p1")
-	tg.grepStderr("import \"x\" is a program, not an importable package", "did not diagnose package main")
-
-	// ... even in that package's test.
-	tg.tempFile("src/p2/p.go", `package p2
-	`)
-	tg.tempFile("src/p2/p_test.go", `package p2
-		import xmain "x"
-		import "testing"
-		var _ = xmain.X
-		func TestFoo(t *testing.T) {}
-	`)
-	tg.run("build", "p2")
-	tg.runFail("test", "p2")
-	tg.grepStderr("import \"x\" is a program, not an importable package", "did not diagnose package main")
-
-	// ... even if that package's test is an xtest.
-	tg.tempFile("src/p3/p.go", `package p
-	`)
-	tg.tempFile("src/p3/p_test.go", `package p_test
-		import xmain "x"
-		import "testing"
-		var _ = xmain.X
-		func TestFoo(t *testing.T) {}
-	`)
-	tg.run("build", "p3")
-	tg.runFail("test", "p3")
-	tg.grepStderr("import \"x\" is a program, not an importable package", "did not diagnose package main")
-
-	// ... even if that package is a package main
-	tg.tempFile("src/p4/p.go", `package main
-	func main() {}
-	`)
-	tg.tempFile("src/p4/p_test.go", `package main
-		import xmain "x"
-		import "testing"
-		var _ = xmain.X
-		func TestFoo(t *testing.T) {}
-	`)
-	tg.creatingTemp("p4" + exeSuffix)
-	tg.run("build", "p4")
-	tg.runFail("test", "p4")
-	tg.grepStderr("import \"x\" is a program, not an importable package", "did not diagnose package main")
-
-	// ... even if that package is a package main using an xtest.
-	tg.tempFile("src/p5/p.go", `package main
-	func main() {}
-	`)
-	tg.tempFile("src/p5/p_test.go", `package main_test
-		import xmain "x"
-		import "testing"
-		var _ = xmain.X
-		func TestFoo(t *testing.T) {}
-	`)
-	tg.creatingTemp("p5" + exeSuffix)
-	tg.run("build", "p5")
-	tg.runFail("test", "p5")
-	tg.grepStderr("import \"x\" is a program, not an importable package", "did not diagnose package main")
-}
-
 // Test that you cannot use a local import in a package
 // accessed by a non-local import (found in a GOPATH/GOROOT).
 // See golang.org/issue/17475.

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

+env GO111MODULE=off
+
+# Test that you cannot import a main package.
+# See golang.org/issue/4210 and golang.org/issue/17475.
+
+[short] skip
+cd $WORK
+
+# Importing package main from that package main's test should work.
+go build x
+go test -c x
+
+# Importing package main from another package should fail.
+! go build p1
+stderr 'import "x" is a program, not an importable package'
+
+# ... even in that package's test.
+go build p2
+! go test -c p2
+stderr 'import "x" is a program, not an importable package'
+
+# ... even if that package's test is an xtest.
+go build p3
+! go test p3
+stderr 'import "x" is a program, not an importable package'
+
+# ... even if that package is a package main
+go build p4
+! go test -c p4
+stderr 'import "x" is a program, not an importable package'
+
+# ... even if that package is a package main using an xtest.
+go build p5
+! go test -c p5
+stderr 'import "x" is a program, not an importable package'
+
+-- x/main.go --
+package main
+
+var X int
+
+func main() {}
+-- x/main_test.go --
+package main_test
+
+import (
+	"testing"
+	xmain "x"
+)
+
+var _ = xmain.X
+
+func TestFoo(t *testing.T) {}
+-- p1/p.go --
+package p1
+
+import xmain "x"
+
+var _ = xmain.X
+-- p2/p.go --
+package p2
+-- p2/p_test.go --
+package p2
+
+import (
+	"testing"
+	xmain "x"
+)
+
+var _ = xmain.X
+
+func TestFoo(t *testing.T) {}
+-- p3/p.go --
+package p
+-- p3/p_test.go --
+package p_test
+
+import (
+	"testing"
+	xmain "x"
+)
+
+var _ = xmain.X
+
+func TestFoo(t *testing.T) {}
+-- p4/p.go --
+package main
+
+func main() {}
+-- p4/p_test.go --
+package main
+
+import (
+	"testing"
+	xmain "x"
+)
+
+var _ = xmain.X
+
+func TestFoo(t *testing.T) {}
+-- p5/p.go --
+package main
+func main() {}
+-- p5/p_test.go --
+package main_test
+
+import (
+	"testing"
+	xmain "x"
+)
+
+var _ = xmain.X
+
+func TestFoo(t *testing.T) {}