Add arch mutator test

Add a test for the arch mutator in preparation for splitting it
into two mutators.

Test: m checkbuild
Change-Id: Ifd0a146a085901d33db50e783bdfad31edd7b7a6
diff --git a/android/arch_test.go b/android/arch_test.go
index 11edb4f..52a6684 100644
--- a/android/arch_test.go
+++ b/android/arch_test.go
@@ -16,6 +16,7 @@
 
 import (
 	"reflect"
+	"runtime"
 	"testing"
 
 	"github.com/google/blueprint/proptools"
@@ -232,3 +233,139 @@
 		})
 	}
 }
+
+type archTestModule struct {
+	ModuleBase
+	props struct {
+		Deps []string
+	}
+}
+
+func (m *archTestModule) GenerateAndroidBuildActions(ctx ModuleContext) {
+}
+
+func (m *archTestModule) DepsMutator(ctx BottomUpMutatorContext) {
+	ctx.AddDependency(ctx.Module(), nil, m.props.Deps...)
+}
+
+func archTestModuleFactory() Module {
+	m := &archTestModule{}
+	m.AddProperties(&m.props)
+	InitAndroidArchModule(m, HostAndDeviceSupported, MultilibBoth)
+	return m
+}
+
+func TestArchMutator(t *testing.T) {
+	var buildOSVariants []string
+	var buildOS32Variants []string
+	switch runtime.GOOS {
+	case "linux":
+		buildOSVariants = []string{"linux_glibc_x86_64", "linux_glibc_x86"}
+		buildOS32Variants = []string{"linux_glibc_x86"}
+	case "darwin":
+		buildOSVariants = []string{"darwin_x86_64"}
+		buildOS32Variants = nil
+	}
+
+	bp := `
+		module {
+			name: "foo",
+		}
+
+		module {
+			name: "bar",
+			host_supported: true,
+		}
+
+		module {
+			name: "baz",
+			device_supported: false,
+		}
+
+		module {
+			name: "qux",
+			host_supported: true,
+			compile_multilib: "32",
+		}
+	`
+
+	mockFS := map[string][]byte{
+		"Android.bp": []byte(bp),
+	}
+
+	testCases := []struct {
+		name        string
+		config      func(Config)
+		fooVariants []string
+		barVariants []string
+		bazVariants []string
+		quxVariants []string
+	}{
+		{
+			name:        "normal",
+			config:      nil,
+			fooVariants: []string{"android_arm64_armv8-a", "android_arm_armv7-a-neon"},
+			barVariants: append(buildOSVariants, "android_arm64_armv8-a", "android_arm_armv7-a-neon"),
+			bazVariants: nil,
+			quxVariants: append(buildOS32Variants, "android_arm_armv7-a-neon"),
+		},
+		{
+			name: "host-only",
+			config: func(config Config) {
+				config.BuildOSTarget = Target{}
+				config.BuildOSCommonTarget = Target{}
+				config.Targets[Android] = nil
+			},
+			fooVariants: nil,
+			barVariants: buildOSVariants,
+			bazVariants: nil,
+			quxVariants: buildOS32Variants,
+		},
+	}
+
+	enabledVariants := func(ctx *TestContext, name string) []string {
+		var ret []string
+		variants := ctx.ModuleVariantsForTests(name)
+		for _, variant := range variants {
+			m := ctx.ModuleForTests(name, variant)
+			if m.Module().Enabled() {
+				ret = append(ret, variant)
+			}
+		}
+		return ret
+	}
+
+	for _, tt := range testCases {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx := NewTestArchContext()
+			ctx.RegisterModuleType("module", ModuleFactoryAdaptor(archTestModuleFactory))
+			ctx.MockFileSystem(mockFS)
+			ctx.Register()
+			config := TestArchConfig(buildDir, nil)
+			if tt.config != nil {
+				tt.config(config)
+			}
+
+			_, errs := ctx.ParseFileList(".", []string{"Android.bp"})
+			FailIfErrored(t, errs)
+			_, errs = ctx.PrepareBuildActions(config)
+			FailIfErrored(t, errs)
+
+			if g, w := enabledVariants(ctx, "foo"), tt.fooVariants; !reflect.DeepEqual(w, g) {
+				t.Errorf("want foo variants:\n%q\ngot:\n%q\n", w, g)
+			}
+
+			if g, w := enabledVariants(ctx, "bar"), tt.barVariants; !reflect.DeepEqual(w, g) {
+				t.Errorf("want bar variants:\n%q\ngot:\n%q\n", w, g)
+			}
+
+			if g, w := enabledVariants(ctx, "baz"), tt.bazVariants; !reflect.DeepEqual(w, g) {
+				t.Errorf("want baz variants:\n%q\ngot:\n%q\n", w, g)
+			}
+
+			if g, w := enabledVariants(ctx, "qux"), tt.quxVariants; !reflect.DeepEqual(w, g) {
+				t.Errorf("want qux variants:\n%q\ngot:\n%q\n", w, g)
+			}
+		})
+	}
+}