Add Rust support to Soong.

Adds support to Soong for building rust modules. This currently only
supports x86_64 device and x86 linux host targets. The functionality
is sufficient to build crosvm.

Bug: 136189233
Test: Test module builds.
Test: crosvm builds.
Change-Id: I6ea04615834a6d673578ab10ea1a2eb04259fe09
diff --git a/rust/testing.go b/rust/testing.go
new file mode 100644
index 0000000..a38697f
--- /dev/null
+++ b/rust/testing.go
@@ -0,0 +1,105 @@
+// Copyright (C) 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 (
+	"android/soong/android"
+)
+
+func GatherRequiredDepsForTest() string {
+	bp := `
+		rust_prebuilt_dylib {
+				name: "libarena_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		rust_prebuilt_dylib {
+				name: "libfmt_macros_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		rust_prebuilt_dylib {
+				name: "libgraphviz_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		rust_prebuilt_dylib {
+				name: "libserialize_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		rust_prebuilt_dylib {
+				name: "libstd_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		rust_prebuilt_dylib {
+				name: "libsyntax_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		rust_prebuilt_dylib {
+				name: "libsyntax_ext_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		rust_prebuilt_dylib {
+				name: "libsyntax_pos_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		rust_prebuilt_dylib {
+				name: "libterm_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		rust_prebuilt_dylib {
+				name: "libtest_x86_64-unknown-linux-gnu",
+				srcs: [""],
+				host_supported: true,
+		}
+		`
+	return bp
+}
+
+func CreateTestContext(bp string) *android.TestContext {
+	ctx := android.NewTestArchContext()
+	ctx.RegisterModuleType("rust_binary", android.ModuleFactoryAdaptor(RustBinaryFactory))
+	ctx.RegisterModuleType("rust_binary_host", android.ModuleFactoryAdaptor(RustBinaryHostFactory))
+	ctx.RegisterModuleType("rust_library", android.ModuleFactoryAdaptor(RustLibraryFactory))
+	ctx.RegisterModuleType("rust_library_host", android.ModuleFactoryAdaptor(RustLibraryHostFactory))
+	ctx.RegisterModuleType("rust_library_host_rlib", android.ModuleFactoryAdaptor(RustLibraryRlibHostFactory))
+	ctx.RegisterModuleType("rust_library_host_dylib", android.ModuleFactoryAdaptor(RustLibraryDylibHostFactory))
+	ctx.RegisterModuleType("rust_library_rlib", android.ModuleFactoryAdaptor(RustLibraryRlibFactory))
+	ctx.RegisterModuleType("rust_library_dylib", android.ModuleFactoryAdaptor(RustLibraryDylibFactory))
+	ctx.RegisterModuleType("rust_proc_macro", android.ModuleFactoryAdaptor(ProcMacroFactory))
+	ctx.RegisterModuleType("rust_prebuilt_dylib", android.ModuleFactoryAdaptor(PrebuiltDylibFactory))
+	ctx.PreDepsMutators(func(ctx android.RegisterMutatorsContext) {
+		ctx.BottomUp("rust_libraries", LibraryMutator).Parallel()
+	})
+	bp = bp + GatherRequiredDepsForTest()
+
+	mockFS := map[string][]byte{
+		"Android.bp": []byte(bp),
+		"foo.rs":     nil,
+		"src/bar.rs": nil,
+		"liby.so":    nil,
+		"libz.so":    nil,
+	}
+
+	ctx.MockFileSystem(mockFS)
+
+	return ctx
+}