Add tests

tests/core/go_binary/BUILD.bazel

@@ -4,6 +4,11 @@ load(":many_deps.bzl", "many_deps")
 
 test_suite(name = "go_binary")
 
+go_bazel_test(
+    name = "configurable_attribute_test",
+    srcs = ["configurable_attribute_test.go"],
+)
+
 go_binary(
     name = "hello",
     srcs = ["hello.go"],

tests/core/go_binary/configurable_attribute_test.go

@@ -0,0 +1,100 @@
+// Copyright 2022 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package configurable_attribute_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/bazelbuild/rules_go/go/tools/bazel_testing"
+)
+
+func TestMain(m *testing.M) {
+	bazel_testing.TestMain(m, bazel_testing.Args{
+		Main: `
+-- BUILD.bazel --
+load("@io_bazel_rules_go//go:def.bzl", "go_binary")
+
+go_binary(
+    name = "main",
+    srcs = ["main.go"],
+    goos = select({
+        "//conditions:default": "darwin",
+    }),
+    goarch = "amd64",
+)
+
+go_binary(
+    name = "configurable_srcs",
+    srcs = select({
+        "@io_bazel_rules_go//go/platform:darwin": ["main_darwin.go"],
+        "//conditions:default": ["main_default.go"],
+    }),
+    goos = select({
+        "//conditions:default": "darwin",
+    }),
+    goarch = "amd64",
+)
+
+-- main.go --
+package main
+
+import "fmt"
+
+func main() {
+  fmt.Println("Hello, World!")
+}
+-- main_darwin.go --
+package main
+
+import "fmt"
+
+func main() {
+    fmt.Println("Hello from darwin, an Apple-shaped operating system")
+}
+-- main_default.go --
+package main
+
+import "fmt"
+
+func main() {
+    fmt.Println("Hello from another operating systems, you'll never find half a worm in this one")
+}
+`,
+	})
+}
+
+func TestConfigurableGOOSAttribute(t *testing.T) {
+	outBytes, err := bazel_testing.BazelOutput("run", "--run_under=file -L", "//:main")
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	out := string(outBytes)
+	if !strings.Contains(out, "Mach-O 64-bit") {
+		t.Fatalf("Wanted darwin executable but got: %s", out)
+	}
+}
+
+func TestConfigurableSrcsWithGOOSTransition(t *testing.T) {
+	outBytes, err := bazel_testing.BazelOutput("run", "--run_under=strings", "//:configurable_srcs")
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	out := string(outBytes)
+    wantSubstr := "Apple-shaped"
+	if !strings.Contains(out, wantSubstr) {
+		t.Fatalf("Wanted executable containing the string %q", wantSubstr)
+	}
+}