aidl: Separate aidl logic into its own static library

Compile aidl's logic into a static library that can be
linked against both the unittest binary and the executable. Validate
that this is working by writing a basic unittest against options
parsing.

Provide default values for Options struct members.  These were
previously taking on values according to the the bits in the memory
allocated to hold them for preprocessed inputs.

Bug: 23516947
Change-Id: Ib57cd7f473995f7851d788deac39f9c4d9018e8f
Test: compiles and unittests pass

tools/aidl/Android.mk

@@ -6,7 +6,10 @@
 ifeq ($(TARGET_BUILD_APPS)$(filter true,$(TARGET_BUILD_PDK)),)
 
 LOCAL_PATH:= $(call my-dir)
+
+# Logic shared between aidl and its unittests
 include $(CLEAR_VARS)
+LOCAL_MODULE := libaidl-common
 
 LOCAL_CLANG_CFLAGS := -Wall -Werror
 # Tragically, the code is riddled with unused parameters.
@@ -29,21 +32,37 @@ LOCAL_SRC_FILES := \
     generate_java.cpp \
     generate_java_binder.cpp \
     generate_java_rpc.cpp \
-    main.cpp \
     options.cpp \
     search_path.cpp \
 
-LOCAL_MODULE := aidl
-LOCAL_MODULE_HOST_OS := darwin linux windows
+include $(BUILD_HOST_STATIC_LIBRARY)
 
+
+# aidl executable
+include $(CLEAR_VARS)
+LOCAL_MODULE := aidl
+
+LOCAL_MODULE_HOST_OS := darwin linux windows
+LOCAL_CFLAGS := -Wall -Werror
+LOCAL_SRC_FILES := main.cpp
+LOCAL_STATIC_LIBRARIES := libaidl-common
 include $(BUILD_HOST_EXECUTABLE)
 
+
 # Unit tests
 include $(CLEAR_VARS)
 LOCAL_MODULE := aidl_unittests
-LOCAL_CFLAGS := -g -DUNIT_TEST
-LOCAL_SRC_FILES := tests/test.cpp
-LOCAL_STATIC_LIBRARIES := libgmock_host libgtest_host libBionicGtestMain
+
+LOCAL_CFLAGS := -g -DUNIT_TEST -Wall -Werror
+LOCAL_SRC_FILES := \
+    options_unittest.cpp \
+    tests/test.cpp \
+
+LOCAL_STATIC_LIBRARIES := \
+    libaidl-common \
+    libgmock_host \
+    libgtest_host \
+    libBionicGtestMain
 LOCAL_LDLIBS := -lrt
 include $(BUILD_HOST_NATIVE_TEST)
 

tools/aidl/options.cpp

@@ -48,10 +48,6 @@ parse_options(int argc, const char* const* argv, Options *options)
         return 0;
     }
 
-    options->task = COMPILE_AIDL;
-    options->failOnParcelable = false;
-    options->autoDepFile = false;
-
     // OPTIONS
     while (i < argc) {
         const char* s = argv[i];

tools/aidl/options.h

@@ -16,15 +16,15 @@ enum {
 // This struct is the parsed version of the command line options
 struct Options
 {
-    int task;
-    bool failOnParcelable;
+    int task{COMPILE_AIDL};
+    bool failOnParcelable{false};
     vector<string> importPaths;
     vector<string> preprocessedFiles;
     string inputFileName;
     string outputFileName;
     string outputBaseFolder;
     string depFileName;
-    bool autoDepFile;
+    bool autoDepFile{false};
 
     vector<string> filesToPreprocess;
 };

tools/aidl/options_unittest.cpp

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2015, 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.
+ */
+
+#include <string>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include "options.h"
+
+using std::vector;
+using std::string;
+
+const char kPreprocessCommandOutputFile[] = "output_file_name";
+const char kPreprocessCommandInput1[] = "input1";
+const char kPreprocessCommandInput2[] = "input2";
+const char kPreprocessCommandInput3[] = "input3";
+const char* kPreprocessCommand[] = {
+    "aidl", "--preprocess",
+    kPreprocessCommandOutputFile,
+    kPreprocessCommandInput1,
+    kPreprocessCommandInput2,
+    kPreprocessCommandInput3,
+};
+
+TEST(OptionsTests, ParsesPreprocess) {
+  Options options;
+  const int argc = sizeof(kPreprocessCommand) / sizeof(*kPreprocessCommand);
+  EXPECT_EQ(parse_options(argc, kPreprocessCommand, &options), 0);
+  EXPECT_EQ(options.task, PREPROCESS_AIDL);
+  EXPECT_EQ(options.failOnParcelable, false);
+  EXPECT_EQ(options.importPaths.size(), 0u);
+  EXPECT_EQ(options.preprocessedFiles.size(), 0u);
+  EXPECT_EQ(options.inputFileName, string{""});
+  EXPECT_EQ(options.outputFileName, string{kPreprocessCommandOutputFile});
+  EXPECT_EQ(options.autoDepFile, false);
+  const vector<string> expected_input{kPreprocessCommandInput1,
+                                      kPreprocessCommandInput2,
+                                      kPreprocessCommandInput3};
+  EXPECT_EQ(options.filesToPreprocess, expected_input);
+}