Add SetUp method to Args for go_bazel_test (#2282)

go/tools/bazel_testing/bazel_testing.go

@@ -59,6 +59,12 @@ type Args struct {
 	// WorkspaceSuffix is a string that should be appended to the end
 	// of the default generated WORKSPACE file.
 	WorkspaceSuffix string
+
+	// SetUp is a function that is executed inside the context of the testing
+	// workspace. It is executed once and only once before the beginning of
+	// all tests. If SetUp returns a non-nil error, execution is halted and
+	// tests cases are not executed.
+	SetUp func() error
 }
 
 // debug may be set to make the test print the test workspace path and stop
@@ -139,6 +145,13 @@ func TestMain(m *testing.M, args Args) {
 	}
 	defer exec.Command("bazel", "shutdown").Run()
 
+	if args.SetUp != nil {
+		if err := args.SetUp(); err != nil {
+			fmt.Fprintf(os.Stderr, "test provided SetUp method returned error: %v\n", err)
+			return
+		}
+	}
+
 	code = m.Run()
 }
 

tests/core/go_bazel_test/dataargtest_test.go

@@ -25,6 +25,7 @@ import (
 
 var (
 	binaryPath = flag.String("binaryPath", "", "")
+	setUpRan   = false
 )
 
 func TestMain(m *testing.M) {
@@ -34,6 +35,10 @@ func TestMain(m *testing.M) {
 Hello world!
 -- nested/file.txt --
 Hello world!`,
+		SetUp: func() error {
+			setUpRan = true
+			return nil
+		},
 	})
 }
 
@@ -57,4 +62,8 @@ func TestGoldenPath(t *testing.T) {
 			t.Fatalf("unable to stat %s file (%q): %s", name, f, err)
 		}
 	}
+
+	if setUpRan == false {
+		t.Fatal("setUp should have been executed but was not")
+	}
 }