Select statements

See the blueprint cl for more information.

Things still to do:
 - Support selecting on product variables and
   variants
 - Test/Support property struct reflection tags
   like arch_variant, path, and variant_prepend
 - Test that selects combine well with existing
   configurability mechanisms like arch:, target:,
   multilib:, python's version:, etc.

Bug: 323382414
Test: go tests
Change-Id: If5d1ea1ad0c4ebabffaea91d62e1a1c6f926a793
diff --git a/android/selects_test.go b/android/selects_test.go
new file mode 100644
index 0000000..dca3789
--- /dev/null
+++ b/android/selects_test.go
@@ -0,0 +1,282 @@
+// Copyright 2024 Google Inc. 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 android
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+
+	"github.com/google/blueprint"
+	"github.com/google/blueprint/proptools"
+)
+
+func TestSelects(t *testing.T) {
+	testCases := []struct {
+		name          string
+		bp            string
+		provider      selectsTestProvider
+		vendorVars    map[string]map[string]string
+		expectedError string
+	}{
+		{
+			name: "basic string list",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_string_list: select(soong_config_variable("my_namespace", "my_variable"), {
+					"a": ["a.cpp"],
+					"b": ["b.cpp"],
+					_: ["c.cpp"],
+				}),
+			}
+			`,
+			provider: selectsTestProvider{
+				my_string_list: &[]string{"c.cpp"},
+			},
+		},
+		{
+			name: "basic string",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_string: select(soong_config_variable("my_namespace", "my_variable"), {
+					"a": "a.cpp",
+					"b": "b.cpp",
+					_: "c.cpp",
+				}),
+			}
+			`,
+			provider: selectsTestProvider{
+				my_string: proptools.StringPtr("c.cpp"),
+			},
+		},
+		{
+			name: "basic bool",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_bool: select(soong_config_variable("my_namespace", "my_variable"), {
+					"a": true,
+					"b": false,
+					_: true,
+				}),
+			}
+			`,
+			provider: selectsTestProvider{
+				my_bool: proptools.BoolPtr(true),
+			},
+		},
+		{
+			name: "Differing types",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_string: select(soong_config_variable("my_namespace", "my_variable"), {
+					"a": "a.cpp",
+					"b": true,
+					_: "c.cpp",
+				}),
+			}
+			`,
+			expectedError: `can't assign bool value to string property "my_string\[1\]"`,
+		},
+		{
+			name: "String list non-default",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_string_list: select(soong_config_variable("my_namespace", "my_variable"), {
+					"a": ["a.cpp"],
+					"b": ["b.cpp"],
+					_: ["c.cpp"],
+				}),
+			}
+			`,
+			provider: selectsTestProvider{
+				my_string_list: &[]string{"a.cpp"},
+			},
+			vendorVars: map[string]map[string]string{
+				"my_namespace": {
+					"my_variable": "a",
+				},
+			},
+		},
+		{
+			name: "String list append",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_string_list: select(soong_config_variable("my_namespace", "my_variable"), {
+					"a": ["a.cpp"],
+					"b": ["b.cpp"],
+					_: ["c.cpp"],
+				}) + select(soong_config_variable("my_namespace", "my_variable_2"), {
+					"a2": ["a2.cpp"],
+					"b2": ["b2.cpp"],
+					_: ["c2.cpp"],
+				}),
+			}
+			`,
+			provider: selectsTestProvider{
+				my_string_list: &[]string{"a.cpp", "c2.cpp"},
+			},
+			vendorVars: map[string]map[string]string{
+				"my_namespace": {
+					"my_variable": "a",
+				},
+			},
+		},
+		{
+			name: "String list prepend literal",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_string_list: ["literal.cpp"] + select(soong_config_variable("my_namespace", "my_variable"), {
+					"a2": ["a2.cpp"],
+					"b2": ["b2.cpp"],
+					_: ["c2.cpp"],
+				}),
+			}
+			`,
+			provider: selectsTestProvider{
+				my_string_list: &[]string{"literal.cpp", "c2.cpp"},
+			},
+		},
+		{
+			name: "String list append literal",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_string_list: select(soong_config_variable("my_namespace", "my_variable"), {
+					"a2": ["a2.cpp"],
+					"b2": ["b2.cpp"],
+					_: ["c2.cpp"],
+				}) + ["literal.cpp"],
+			}
+			`,
+			provider: selectsTestProvider{
+				my_string_list: &[]string{"c2.cpp", "literal.cpp"},
+			},
+		},
+		{
+			name: "Can't append bools",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_bool: select(soong_config_variable("my_namespace", "my_variable"), {
+					"a": true,
+					"b": false,
+					_: true,
+				}) + false,
+			}
+			`,
+			expectedError: "my_bool: Cannot append bools",
+		},
+		{
+			name: "Append string",
+			bp: `
+			my_module_type {
+				name: "foo",
+				my_string: select(soong_config_variable("my_namespace", "my_variable"), {
+					"a": "a",
+					"b": "b",
+					_: "c",
+				}) + ".cpp",
+			}
+			`,
+			provider: selectsTestProvider{
+				my_string: proptools.StringPtr("c.cpp"),
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			fixtures := GroupFixturePreparers(
+				FixtureRegisterWithContext(func(ctx RegistrationContext) {
+					ctx.RegisterModuleType("my_module_type", newSelectsMockModule)
+				}),
+				FixtureModifyProductVariables(func(variables FixtureProductVariables) {
+					variables.VendorVars = tc.vendorVars
+				}),
+			)
+			if tc.expectedError != "" {
+				fixtures = fixtures.ExtendWithErrorHandler(FixtureExpectsOneErrorPattern(tc.expectedError))
+			}
+			result := fixtures.RunTestWithBp(t, tc.bp)
+
+			if tc.expectedError == "" {
+				m := result.ModuleForTests("foo", "")
+				p, _ := OtherModuleProvider[selectsTestProvider](result.testContext.OtherModuleProviderAdaptor(), m.Module(), selectsTestProviderKey)
+				if !reflect.DeepEqual(p, tc.provider) {
+					t.Errorf("Expected:\n  %q\ngot:\n  %q", tc.provider.String(), p.String())
+				}
+			}
+		})
+	}
+}
+
+type selectsTestProvider struct {
+	my_bool        *bool
+	my_string      *string
+	my_string_list *[]string
+}
+
+func (p *selectsTestProvider) String() string {
+	myBoolStr := "nil"
+	if p.my_bool != nil {
+		myBoolStr = fmt.Sprintf("%t", *p.my_bool)
+	}
+	myStringStr := "nil"
+	if p.my_string != nil {
+		myStringStr = *p.my_string
+	}
+	return fmt.Sprintf(`selectsTestProvider {
+	my_bool: %v,
+	my_string: %s,
+    my_string_list: %s,
+}`, myBoolStr, myStringStr, p.my_string_list)
+}
+
+var selectsTestProviderKey = blueprint.NewProvider[selectsTestProvider]()
+
+type selectsMockModuleProperties struct {
+	My_bool        proptools.Configurable[bool]
+	My_string      proptools.Configurable[string]
+	My_string_list proptools.Configurable[[]string]
+}
+
+type selectsMockModule struct {
+	ModuleBase
+	DefaultableModuleBase
+	properties selectsMockModuleProperties
+}
+
+func (p *selectsMockModule) GenerateAndroidBuildActions(ctx ModuleContext) {
+	SetProvider[selectsTestProvider](ctx, selectsTestProviderKey, selectsTestProvider{
+		my_bool:        p.properties.My_bool.Evaluate(ctx),
+		my_string:      p.properties.My_string.Evaluate(ctx),
+		my_string_list: p.properties.My_string_list.Evaluate(ctx),
+	})
+}
+
+func newSelectsMockModule() Module {
+	m := &selectsMockModule{}
+	m.AddProperties(&m.properties)
+	InitAndroidArchModule(m, HostAndDeviceSupported, MultilibCommon)
+	InitDefaultableModule(m)
+	return m
+}