Add rust_test and rust_test_host.

* Rust tests are like binary files compiled with --test.
  New test.go follows binary.go code patterns and reuses
  some code in binary.go.
* Generate one test per source file as testPerSrc in cc/test.go.
  The "all tests" variation feature of cc/test.go is not copied yet.
  Fix some Stem and SubName settings to make testPerSrc work.
* Move cc.CheckDuplicate to android.CheckDuplicate,
  which is now shared by cc and rust.
* Refactor tests in binary_test.go and add new test_test.go.

Bug: 140938178
Test: mm in rust projects, added rust_test and rust_test_host
Change-Id: Ia6fec8b4cf2572fd352ab1938a1f3c7b5cca2212
diff --git a/rust/androidmk.go b/rust/androidmk.go
index f933cfb..49115f2 100644
--- a/rust/androidmk.go
+++ b/rust/androidmk.go
@@ -72,6 +72,8 @@
 
 	mod.subAndroidMk(&ret, mod.compiler)
 
+	ret.SubName += mod.Properties.SubName
+
 	return ret
 }
 
@@ -85,6 +87,11 @@
 	})
 }
 
+func (test *testBinaryDecorator) AndroidMk(ctx AndroidMkContext, ret *android.AndroidMkData) {
+	test.binaryDecorator.AndroidMk(ctx, ret)
+	ret.SubName = "_" + String(test.baseCompiler.Properties.Stem)
+}
+
 func (library *libraryDecorator) AndroidMk(ctx AndroidMkContext, ret *android.AndroidMkData) {
 	ctx.subAndroidMk(ret, library.baseCompiler)
 
diff --git a/rust/binary_test.go b/rust/binary_test.go
index cd41fcf..ab2dae1 100644
--- a/rust/binary_test.go
+++ b/rust/binary_test.go
@@ -36,11 +36,20 @@
 	fizzBuzz := ctx.ModuleForTests("fizz-buzz", "linux_glibc_x86_64").Output("fizz-buzz")
 	fizzBuzzDynamic := ctx.ModuleForTests("fizz-buzz-dynamic", "linux_glibc_x86_64").Output("fizz-buzz-dynamic")
 
-	if !strings.Contains(fizzBuzzDynamic.Args["rustcFlags"], "prefer-dynamic") {
-		t.Errorf("missing prefer-dynamic flag, rustcFlags: %#v", fizzBuzzDynamic.Args["rustcFlags"])
+	// Do not compile binary modules with the --test flag.
+	flags := fizzBuzzDynamic.Args["rustcFlags"]
+	if strings.Contains(flags, "--test") {
+		t.Errorf("extra --test flag, rustcFlags: %#v", flags)
+	}
+	if !strings.Contains(flags, "prefer-dynamic") {
+		t.Errorf("missing prefer-dynamic flag, rustcFlags: %#v", flags)
 	}
 
-	if strings.Contains(fizzBuzz.Args["rustcFlags"], "prefer-dynamic") {
-		t.Errorf("unexpected prefer-dynamic flag, rustcFlags: %#v", fizzBuzz.Args["rustcFlags"])
+	flags = fizzBuzz.Args["rustcFlags"]
+	if strings.Contains(flags, "--test") {
+		t.Errorf("extra --test flag, rustcFlags: %#v", flags)
+	}
+	if strings.Contains(flags, "prefer-dynamic") {
+		t.Errorf("unexpected prefer-dynamic flag, rustcFlags: %#v", flags)
 	}
 }
diff --git a/rust/rust.go b/rust/rust.go
index ce81b91..ec3b590 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -39,6 +39,7 @@
 	android.RegisterModuleType("rust_defaults", defaultsFactory)
 	android.PreDepsMutators(func(ctx android.RegisterMutatorsContext) {
 		ctx.BottomUp("rust_libraries", LibraryMutator).Parallel()
+		ctx.BottomUp("rust_unit_tests", TestPerSrcMutator).Parallel()
 	})
 	pctx.Import("android/soong/rust/config")
 }
@@ -58,6 +59,7 @@
 	AndroidMkProcMacroLibs []string
 	AndroidMkSharedLibs    []string
 	AndroidMkStaticLibs    []string
+	SubName                string `blueprint:"mutated"`
 }
 
 type Module struct {
@@ -495,9 +497,10 @@
 }
 
 var (
-	rlibDepTag      = dependencyTag{name: "rlibTag", library: true}
-	dylibDepTag     = dependencyTag{name: "dylib", library: true}
-	procMacroDepTag = dependencyTag{name: "procMacro", proc_macro: true}
+	rlibDepTag       = dependencyTag{name: "rlibTag", library: true}
+	dylibDepTag      = dependencyTag{name: "dylib", library: true}
+	procMacroDepTag  = dependencyTag{name: "procMacro", proc_macro: true}
+	testPerSrcDepTag = dependencyTag{name: "rust_unit_tests"}
 )
 
 func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
diff --git a/rust/test.go b/rust/test.go
new file mode 100644
index 0000000..816e3c7
--- /dev/null
+++ b/rust/test.go
@@ -0,0 +1,116 @@
+// Copyright 2019 The Android Open Source Project
+//
+// 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 rust
+
+import (
+	"path/filepath"
+	"strings"
+
+	"android/soong/android"
+)
+
+// A test module is a binary module with extra --test compiler flag
+// and different default installation directory.
+// In golang, inheriance is written as a component.
+type testBinaryDecorator struct {
+	*binaryDecorator
+}
+
+func NewRustTest(hod android.HostOrDeviceSupported) (*Module, *testBinaryDecorator) {
+	module := newModule(hod, android.MultilibFirst)
+
+	test := &testBinaryDecorator{
+		binaryDecorator: &binaryDecorator{
+			// TODO(chh): set up dir64?
+			baseCompiler: NewBaseCompiler("testcases", ""),
+		},
+	}
+
+	module.compiler = test
+
+	return module, test
+}
+
+func (test *testBinaryDecorator) compilerFlags(ctx ModuleContext, flags Flags) Flags {
+	flags = test.binaryDecorator.compilerFlags(ctx, flags)
+	flags.RustFlags = append(flags.RustFlags, "--test")
+	return flags
+}
+
+func init() {
+	// Rust tests are binary files built with --test.
+	android.RegisterModuleType("rust_test", RustTestFactory)
+	android.RegisterModuleType("rust_test_host", RustTestHostFactory)
+}
+
+func RustTestFactory() android.Module {
+	module, _ := NewRustTest(android.HostAndDeviceSupported)
+	return module.Init()
+}
+
+func RustTestHostFactory() android.Module {
+	module, _ := NewRustTest(android.HostSupported)
+	return module.Init()
+}
+
+func (test *testBinaryDecorator) testPerSrc() bool {
+	return true
+}
+
+func (test *testBinaryDecorator) srcs() []string {
+	return test.Properties.Srcs
+}
+
+func (test *testBinaryDecorator) setSrc(name, src string) {
+	test.Properties.Srcs = []string{src}
+	test.baseCompiler.Properties.Stem = StringPtr(name)
+}
+
+func (test *testBinaryDecorator) unsetSrc() {
+	test.Properties.Srcs = nil
+	test.baseCompiler.Properties.Stem = StringPtr("")
+}
+
+type testPerSrc interface {
+	testPerSrc() bool
+	srcs() []string
+	setSrc(string, string)
+	unsetSrc()
+}
+
+var _ testPerSrc = (*testBinaryDecorator)(nil)
+
+func TestPerSrcMutator(mctx android.BottomUpMutatorContext) {
+	if m, ok := mctx.Module().(*Module); ok {
+		if test, ok := m.compiler.(testPerSrc); ok {
+			numTests := len(test.srcs())
+			if test.testPerSrc() && numTests > 0 {
+				if duplicate, found := android.CheckDuplicate(test.srcs()); found {
+					mctx.PropertyErrorf("srcs", "found a duplicate entry %q", duplicate)
+					return
+				}
+				testNames := make([]string, numTests)
+				for i, src := range test.srcs() {
+					testNames[i] = strings.TrimSuffix(filepath.Base(src), filepath.Ext(src))
+				}
+				// TODO(chh): Add an "all tests" variation like cc/test.go?
+				tests := mctx.CreateLocalVariations(testNames...)
+				for i, src := range test.srcs() {
+					tests[i].(*Module).compiler.(testPerSrc).setSrc(testNames[i], src)
+				}
+			}
+		}
+	}
+}
diff --git a/rust/test_test.go b/rust/test_test.go
new file mode 100644
index 0000000..aa4c3c8
--- /dev/null
+++ b/rust/test_test.go
@@ -0,0 +1,43 @@
+// Copyright 2019 The Android Open Source Project
+//
+// 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 rust
+
+import (
+	"strings"
+	"testing"
+)
+
+// Check if rust_test_host accepts multiple source files and applies --test flag.
+func TestRustTest(t *testing.T) {
+	ctx := testRust(t, `
+		rust_test_host {
+			name: "my_test",
+			srcs: ["foo.rs", "src/bar.rs"],
+			relative_install_path: "rust/my-test",
+		}`)
+
+	for _, name := range []string{"foo", "bar"} {
+		testingModule := ctx.ModuleForTests("my_test", "linux_glibc_x86_64_"+name)
+		testingBuildParams := testingModule.Output(name)
+		rustcFlags := testingBuildParams.Args["rustcFlags"]
+		if !strings.Contains(rustcFlags, "--test") {
+			t.Errorf("%v missing --test flag, rustcFlags: %#v", name, rustcFlags)
+		}
+		outPath := "/my_test/linux_glibc_x86_64_" + name + "/" + name
+		if !strings.Contains(testingBuildParams.Output.String(), outPath) {
+			t.Errorf("wrong output: %v  expect: %v", testingBuildParams.Output, outPath)
+		}
+	}
+}
diff --git a/rust/testing.go b/rust/testing.go
index cd63084..24defa6 100644
--- a/rust/testing.go
+++ b/rust/testing.go
@@ -168,6 +168,8 @@
 	ctx.RegisterModuleType("cc_object", android.ModuleFactoryAdaptor(cc.ObjectFactory))
 	ctx.RegisterModuleType("rust_binary", android.ModuleFactoryAdaptor(RustBinaryFactory))
 	ctx.RegisterModuleType("rust_binary_host", android.ModuleFactoryAdaptor(RustBinaryHostFactory))
+	ctx.RegisterModuleType("rust_test", android.ModuleFactoryAdaptor(RustTestFactory))
+	ctx.RegisterModuleType("rust_test_host", android.ModuleFactoryAdaptor(RustTestHostFactory))
 	ctx.RegisterModuleType("rust_library", android.ModuleFactoryAdaptor(RustLibraryFactory))
 	ctx.RegisterModuleType("rust_library_host", android.ModuleFactoryAdaptor(RustLibraryHostFactory))
 	ctx.RegisterModuleType("rust_library_host_rlib", android.ModuleFactoryAdaptor(RustLibraryRlibHostFactory))
@@ -190,6 +192,7 @@
 
 		// rust mutators
 		ctx.BottomUp("rust_libraries", LibraryMutator).Parallel()
+		ctx.BottomUp("rust_unit_tests", TestPerSrcMutator).Parallel()
 	})
 	bp = bp + GatherRequiredDepsForTest()