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Clean Architecture &
TDD
@fushiroyama
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About Me
• Fumihiko Shiroyama
• Android App Developer
• Unit Test Enthusiast
• https://github.com/srym
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Clean Architecture
• Presentation
• Domain
• Infrastructure
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TDD
• Test Driven Development
• Test First
• Minimum Implementation
• Refactoring
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TDD is great! because...
• Focus on I/O
• Less reworking
• Force Unit Testing
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Example
• Infrastructure
• Remote Data Source
• GitHub Information
• Local Unit Test
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Interface
public interface RemoteGitHubDataSource {
Single> listRepos(@NonNull String user);
}
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Blank Implementation
public class RestGitHubDataSource
implements RemoteGitHubDataSource {
@Override
public Single> listRepos(@NonNull String user) {
return Single.error(new RuntimeException());
}
}
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Blank Implementation
public class RestGitHubDataSource
implements RemoteGitHubDataSource {
@Override
public Single> listRepos(@NonNull String user) {
return Single.error(new RuntimeException());
}
}
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Create Test
• Mouse over class
• Alt + Enter
• Create Test
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Create Test
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Create Test
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By the way...
• Mouse over class
• Shift + Command + T
• Choose Test
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Test First
public class RestGitHubDataSourceTest {
private RestGitHubDataSource dataSource;
@Before
public void setUp() throws Exception {
dataSource = new RestGitHubDataSource();
}
@Test
public void listRepos() throws Exception {
// implement here!
}
}
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Test First
@Test
public void listRepos() throws Exception {
List repos = restGitHubDataSource.listRepos("srym")
.test()
.await()
.assertNoErrors()
.assertComplete()
.values()
.get(0);
assertThat(repos).isNotNull();
}
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Test First
assertThat(repos).isNotNull().isNotEmpty();
Repo repo = repos.get(0);
assertThat(repo).isNotNull();
assertThat(repo.getFullName()).isNotBlank();
assertThat(repo.getId()).isGreaterThanOrEqualTo(0);
assertThat(repo.getOwner()).isNotNull();
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Test First
assertThat(repos).isNotNull().isNotEmpty();
Repo repo = repos.get(0);
assertThat(repo).isNotNull();
assertThat(repo.getFullName()).isNotBlank();
assertThat(repo.getId()).isGreaterThanOrEqualTo(0);
assertThat(repo.getOwner()).isNotNull();
You can confirm the specs
BEFORE you implement
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Test Execution (failure)
• This of course fails.
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Minimum Implementation
public class RestGitHubDataSource implements RemoteGitHubDataSource {
private final GitHubService gitHubService;
@Inject
public RestGitHubDataSource(GitHubService gitHubService) {
this.gitHubService = gitHubService;
}
@Override
public Single> listRepos(@NonNull String user) {
return gitHubService.listRepos(user);
}
}
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Minimum Implementation
public class RestGitHubDataSource implements RemoteGitHubDataSource {
private final GitHubService gitHubService;
@Inject
public RestGitHubDataSource(GitHubService gitHubService) {
this.gitHubService = gitHubService;
}
@Override
public Single> listRepos(@NonNull String user) {
return gitHubService.listRepos(user);
}
}
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Minimum Implementation
public class RestGitHubDataSource implements RemoteGitHubDataSource {
private final GitHubService gitHubService;
@Inject
public RestGitHubDataSource(GitHubService gitHubService) {
this.gitHubService = gitHubService;
}
@Override
public Single> listRepos(@NonNull String user) {
return gitHubService.listRepos(user);
}
}
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But wait...
• This is Local Unit Test
• Mock data? Hmm.
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MockWebServer
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MockWebServer
• Provided by OkHttp
• Full HTTP Stack
• Can test REAL response
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MockWebServer
private final MockWebServer mockWebServer
= new MockWebServer();
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MockWebServer
Dispatcher dispatcher = new Dispatcher() {
@Override
public MockResponse dispatch(RecordedRequest request)
throws InterruptedException {
return new MockResponse().setResponseCode(404);
}
};
mockWebServer.setDispatcher(dispatcher);
mockWebServer.start();
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MockWebServer
@Override
public MockResponse dispatch(RecordedRequest request) throws
InterruptedException {
if (request == null || request.getPath() == null) {
return new MockResponse().setResponseCode(400);
}
if (request.getPath().matches("/users/.+/repos")) {
return new MockResponse()
.setBody(readJsonFromResources("users_repos.json"))
.setResponseCode(200);
}
return new MockResponse().setResponseCode(404);
}
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MockWebServer
@Override
public MockResponse dispatch(RecordedRequest request) throws
InterruptedException {
if (request == null || request.getPath() == null) {
return new MockResponse().setResponseCode(400);
}
if (request.getPath().matches("/users/.+/repos")) {
return new MockResponse()
.setBody(readJsonFromResources("users_repos.json"))
.setResponseCode(200);
}
return new MockResponse().setResponseCode(404);
}
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MockWebServer
@Override
public MockResponse dispatch(RecordedRequest request) throws
InterruptedException {
if (request == null || request.getPath() == null) {
return new MockResponse().setResponseCode(400);
}
if (request.getPath().matches("/users/.+/repos")) {
return new MockResponse()
.setBody(readJsonFromResources("users_repos.json"))
.setResponseCode(200);
}
return new MockResponse().setResponseCode(404);
}
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MockWebServer
@Override
public MockResponse dispatch(RecordedRequest request) throws
InterruptedException {
if (request == null || request.getPath() == null) {
return new MockResponse().setResponseCode(400);
}
if (request.getPath().matches("/users/.+/repos")) {
return new MockResponse()
.setBody(readJsonFromResources("users_repos.json"))
.setResponseCode(200);
}
return new MockResponse().setResponseCode(404);
}
Talk about this later
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MockWebServer
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(mockWebServer.url(""))
.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
.addConverterFactory(GsonConverterFactory.create())
.build();
GitHubService gitHubService = retrofit.create(GitHubService.class);
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MockWebServer
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(mockWebServer.url(""))
.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
.addConverterFactory(GsonConverterFactory.create())
.build();
GitHubService gitHubService = retrofit.create(GitHubService.class);
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Prepare Data
• Curl
• Postman
curl https://api.github.com/users/srym/repos >
users_repos.json
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Prepare Data
• Put it test/resources
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Read JSON from file
private String readJsonFromResources(@NonNull String fileName) {
InputStream inputStream
= getClass().getClassLoader().getResourceAsStream(fileName);
BufferedReader bufferedReader
= new BufferedReader(new InputStreamReader(inputStream));
StringBuilder stringBuilder = new StringBuilder();
try {
String buffer;
while ((buffer = bufferedReader.readLine()) != null) {
stringBuilder.append(buffer);
}
} catch (IOException e) {
fail(e.getMessage(), e);
}
return stringBuilder.toString();
}
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Fix Test
@Before
public void setUp() throws Exception {
// abbr.
dataSource = new RestGitHubDataSource(gitHubService);
}
@Test
public void listRepos() throws Exception {
List repos = restGitHubDataSource.listRepos("srym")
.test()
.await()
.assertNoErrors()
.assertComplete()
.values()
.get(0);
assertThat(repos).isNotNull();
// abbr.
}
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Passed!
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Refactoring
• TDD is NOT perfect
• Repeat Write & Test
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Cons
• Useless when API changes
• Takes longer time
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Pros
• Quality
• Relief
• Takes shorter time in total
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TDD rocks!
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Thank You
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Links
• https://github.com/srym/Architecture
• https://github.com/square/okhttp/tree/
master/mockwebserver
• http://www.irasutoya.com/