アプリをリリースできる状態に保ったまま段階的にリファクタリングするための戦略と戦術 / Strategies and tactics for incremental refactoring

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for incremental refactoring 1

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[versions] … hilt = “2.52" kotlin = "2.0.10" ksp =
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plugins { … alias(libs.plugins.hilt) apply false alias(libs.plugins.ksp) apply false }
plugins { … alias(libs.plugins.hilt) alias(libs.plugins.ksp) } dependencies { … implementation(libs.hilt.android) ksp(libs.hilt.compiler) } project level build.gradle module level build.gradle 56

@HiltAndroidApp class MyApplication : Application() { … } <application android:name=".MyApplication"
…> … </application> AndroidManifest.xml 57

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app module αʔόʔͱ ௨৴͢Δ෦෼ JSON UI { “name” : “…”,
… } ItemResponse As-Is 59

app module αʔόʔͱ ௨৴͢Δ෦෼ JSON UI Repository (Old) ItemResponse ViewModel
api module Item core module Item Item To-Be 60

public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle
savedInstanceState) { … VolleyUtil.getInstance(this).request( new ItemsRequest( response -> { recyclerViewAdapter.submitList(response); }, error -> { … } ) ); } … } As-Is 61

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app module api module core module dependencies { implementation(project(":core")) …
} dependencies { implementation(project(":core")) implementation(project(":api")) … } 63

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internal interface MyApiClient { @GET("/items") suspend fun getItems(): List<ItemResponse> }
@Serializable internal data class ItemResponse( @SerialName("id") val id: Int, @SerialName("name") val name: String, ) JSON MyApiClient ItemResponse api module 65

interface MyApi { suspend fun getItems(): List<Item> } internal class
DefaultMyApi( private val apiClient: MyApiClient ) : MyApi { override suspend fun getItems(): List<Item> { val response = apiClient.getItems() return response.map { ItemMapper(it) } } } core module Item JSON api module DefaultMyApi MyApiClient Item ItemResponse MyApi implements 66

e.g. { "status" : "NG", "message" : "invalid request parameter"
} { "status" : "OK", "data" : { ... } } success error 67

{ "status" : "NG", "message" : "invalid request parameter" }
{ "status" : "OK", "data" : { ... } } success error @Serializable internal data class DataResponse( @SerialName("status") val status: String, @SerialName("message") val message: String?, @SerialName("data") val data: Data?, ) { @Serializable data class Data( @SerialName("id") val id: Int, … ) } e.g. 68

internal class DefaultMyApi( private val apiClient: MyApiClient ) : MyApi
{ override suspend fun getData(): Data { val response = apiClient.getData() if (response.status != "OK") { throw MyApiException.InvalidRequest( message = "status = ${response.status}, message = ${response.mess ) } val data = response.data ?: throw MyApiException.InvalidResponse( message = "data was null", ) return DataMapper(data) } } e.g. de fi ned in core module 69

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module 71

object MyApiFactory { fun create( baseUrl: String, tokenProvider: () ->
String?, … ): MyApi { val apiClient = Retrofit.Builder() .baseUrl(baseUrl) .client( OkHttpClient.Builder() .addInterceptor { chain -> … } .build(), ) … .build() .create(MyApiClient::class.java) return DefaultMyApi(apiClient) } } api module 72

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instantiate api module 73

app module @InstallIn(SingletonComponent::class) @Module object AppModule { @Singleton @Provides fun
provideMyApi( … ): MyApi { return MyApiFactory.create( tokenProvider = { … }, … ) } } object MyApiFactory { … fun create( … ): MyApi { … } } api module 74

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MyApi api module 75

interface TokenProvider { fun provide(): String? } MyApi DefaultMyApi implements
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internal object MyApiFactory { … } @InstallIn(SingletonComponent::class) @Module object ApiModule
{ @Singleton @Provides fun provideMyApi( tokenProvider: TokenProvider, … ): MyApi { return MyApiFactory.create( tokenProvider::provide, … ) } } api module interface TokenProvider { fun provide(): String? } 77

class DefaultTokenProvider( … ) : TokenProvider { override fun provide():
String? { return … } } MyApi DefaultMyApi implements MyApiFactory instantiate app module Hilt TokenProvider implements of TokenProvider MyApi implements api module app module uses 78

MyApi DefaultMyApi implements MyApiFactory instantiate app module Hilt TokenProvider implements
of TokenProvider MyApi implements Hilt Module api module uses app module @InstallIn(SingletonComponent::class) @Module object AppModule { @Singleton @Provides fun provideTokenProvider( … ): TokenProvider { return DefaultTokenProvider( … ) } } 79

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api/src/test/resources/items.json [ { "id": "item id", "name": "item name" }
] internal object TestResourceReader { fun readFileAsString( fileName: String, charset: Charset = Charset.defaultCharset(), ): String { return javaClass.classLoader!!.getResource(fileName).readText(charset) } } api/src/test/kotlin/… 81

@Test fun items_success() = runTest { val server = MockWebServer().apply
{ enqueue( MockResponse().setBody( TestResourceReader.readFileAsString("items.json") ) ) start() } val baseUrl = server.url("/").toString() val token = UUID.randomUUID().toString() val api = MyApiFactory.create( baseUrl = baseUrl, tokenProvider = { token } ) val items = api.getItems() 82

val items = api.getItems() assertEquals( listOf( Item( id = ItemId("item
id"), name = "item name" ) ), items ) val request = server.takeRequest() assertEquals("/items", request.path) assertEquals( "Bearer $token", request.getHeader("Authorization") ) server.shutdown() } 83

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DefaultItemRepository @Inject constructor( private val myApi: MyApi ) : ItemRepository { override suspend fun getItems(): ApiResult<List<Item>> { return try { val result = myApi.getItems() ApiResult.Success(result) } catch (e: MyApiException) { ApiResult.Error(e) } } } 85

5FTU class DefaultItemRepositoryTest { private lateinit var repository: ItemRepository private
lateinit var api: MyApi @Before fun setup() { api = mockk() repository = DefaultItemRepository(api) } @Test fun success() = runTest { coEvery { api.getItems() } returns listOf(…) val result = repository.getItems() assertEquals(ApiResult.Success(listOf(…)), result) } @Test fun error() = runTest { … } } 86

@InstallIn(SingletonComponent::class) @Module interface BindModule { @Singleton @Binds fun bindItemRepository( defaultImplementation:
DefaultItemRepository ): ItemRepository } class DefaultItemRepository @Inject constructor( private val myApi: MyApi ) : ItemRepository { … } 87

MyApi JSON Repository Item core module Item app module api
module 88

module UI (Old) ItemResponse 89

module UI (Old) ItemResponse ViewModel Item convert Item to (Old) ItemResponse 90

fun Item.toItemResponse(): ItemResponse { return ItemResponse( id = id.value, iconUrl
= iconUrl, name = title, ) } class ItemTest { @Test fun toItemResponse() { val item = Item(…) val itemResponse = item.toItemResponse() assertEquals( ItemResponse(…), itemResponse ) } } @Deprecated("use Item in core module") data class ItemResponse( … ) 91

@HiltViewModel class MainViewModel @Inject constructor( private val itemRepository: ItemRepository, )
: ViewModel() { fun request( onSuccess: (List<ItemResponse>) -> Unit, onError: (Exception) -> Unit, ) { viewModelScope.launch { when (val result = itemRepository.getItems()) { is ApiResult.Error -> { onError(result.e) } is ApiResult.Success -> { onSuccess(result.data.map { it.toItemResponse() }) } } } } } ❌ 92

❌ @AndroidEntryPoint public class MainActivity extends AppCompatActivity { @Override protected
void onCreate(Bundle savedInstanceState) { … MainViewModel viewModel = new ViewModelProvider(this).get(MainViewModel viewModel.request( VolleyUtil.getInstance(this).request( new ItemsRequest( response -> { recyclerViewAdapter.submitList(response); return Unit.INSTANCE; }, error -> { … return Unit.INSTANCE; } ) ); } … 93

: ViewModel() { fun request( onSuccess: (List<ItemResponse>) -> Unit, onError: (Exception) -> Unit, ) { viewModelScope.launch { when (val result = itemRepository.getItems()) { is ApiResult.Error -> { onError(result.e) } is ApiResult.Success -> { onSuccess(result.data.map { it.toItemResponse() }) } } } } } ❌ 94

: ViewModel() { private val _items = MutableLiveData<ApiResult<List<ItemResponse>>>() val items: LiveData<ApiResult<List<ItemResponse>>> get() = _items fun request() { viewModelScope.launch { when (val result = itemRepository.getItems()) { is ApiResult.Error -> _items.postValue(result) is ApiResult.Success -> _items.postValue( ApiResult.Success(result.data.map { it.toItemResponse() }) ) } } } } 95

@AndroidEntryPoint public class MainActivity extends AppCompatActivity { @Override protected void
onCreate(Bundle savedInstanceState) { … MainViewModel viewModel = new ViewModelProvider(this).get(MainViewModel.class); viewModel.getItems().observe( this, result -> { if (result instanceof ApiResult.Success<List<ItemResponse>> response) { adapter.submitList(response.getData()); } else if (result instanceof ApiResult.Error error) { … } } ); viewModel.request(); } … 96

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,PUMJOԽͷॱ൪ TUBUJDͳΫϥεΛUPQMFWFMʹҠಈ public class ItemAdapter extends ListAdapter<ItemResponse, ItemViewHolder> {
… public static class ItemHolder extends RecyclerView.ViewHolder { … } } public class ItemHolder extends RecyclerView.ViewHolder { … } 99

,PUMJOԽͷॱ൪ TUBUJDͳΫϥεΛUPQMFWFMʹҠಈ TUBUJD͡Όͳ͍JOOFSDMBTTΛTUBUJDʹͯ͠UPQMFWFMʹҠಈ 100

public class MainActivity extends AppCompatActivity { … private void onClickItem(Item
item) { … } class ItemAdapter extends ListAdapter<Item, ItemViewHolder> { … @Override public void onBindViewHolder(@NonNull ItemViewHolder holder, int position) { holder.itemView.setOnClickListener(view -> { onClickItem(getItem(position)); }); } } } 101

public class MainActivity extends AppCompatActivity { … private void onClickItem(Item
item) { … } static class ItemAdapter extends ListAdapter<Item, ItemViewHolder> { private final OnClickListener onClickItemListener; protected ItemAdapter3(OnClickListener listener) { … this.onClickItemListener = listener; } @Override public void onBindViewHolder(@NonNull ItemViewHolder holder, int position) { holder.itemView.setOnClickListener(view -> { onClickItemListener.onClick(getItem(position)); }); } } } 102

,PUMJOԽͷॱ൪ TUBUJDͳΫϥεΛUPQMFWFMʹҠಈ TUBUJD͡Όͳ͍JOOFSDMBTTΛTUBUJDʹͯ͠UPQMFWFMʹҠಈ ͜ͷΫϥεͷ੹຿Ͱ͸ͳ͍ॲཧΛɺผΫϥεΛ࡞ͬͯҕৡ 103

,PUMJOԽͷॱ൪ TUBUJDͳΫϥεΛUPQMFWFMʹҠಈ TUBUJD͡Όͳ͍JOOFSDMBTTΛTUBUJDʹͯ͠UPQMFWFMʹҠಈ ͜ͷΫϥεͷ੹຿Ͱ͸ͳ͍ॲཧΛɺผΫϥεΛ࡞ͬͯҕৡ͢Δ )FMQFSతͳDMBTTPCKFDUΛLPUMJOͰ༻ҙ͠ɺߦ͘Β͍ʹͳΔ·Ͱϝ ιουΛҠಈ͢Δ
104

,PUMJOԽͷॱ൪ TUBUJDͳΫϥεΛUPQMFWFMʹҠಈ TUBUJD͡Όͳ͍JOOFSDMBTTΛTUBUJDʹͯ͠UPQMFWFMʹҠಈ ͜ͷΫϥεͷ੹຿Ͱ͸ͳ͍ॲཧΛɺผΫϥεΛ࡞ͬͯҕৡ͢Δ )FMQFSతͳDMBTTPCKFDUΛLPUMJOͰ༻ҙ͠ɺߦ͘Β͍ʹͳΔ·Ͱϝ ιουΛҠಈ͢Δ
LPUMJOԽ͠ɺIFMQFSΫϥεͱ߹ମ 105

,PUMJOԽͷDPNNJU த਎͕+BWBͷ··֦ுࢠΛKBWB͔ΒLUʹม͑ͯDPNNJU͢Δ ֦ுࢠΛLU͔ΒKBWBʹ໭͢ʢDPNNJU͠ͳ͍ʣ ,PUMJOԽͯ͠DPNNJU͢Δ % mv ItemAdapter.java
ItemAdapter.java.kt % git add -A % git commit -m 'rename ItemAdapter.java to ItemAdapter.kt' % mv ItemAdapter.kt ItemAdapter.java % git add -A % git commit -m 'Kotlinize ItemAdapter' 106

,PUMJOԽͷDPNNJU 107

$PNQPTF΁ͷҠߦ

"CTUSBDU$PNQPTF7JFXΛܧঝͨ͠$VTUPN7JFX class DetailActivityComposeView @JvmOverloads constructor( context: Context, attrs: AttributeSet? =
null, defStyleAttr: Int = 0, ) : AbstractComposeView(context, attrs, defStyleAttr) { @Composable override fun Content() { MyTheme { } } } 109

$PNQPTF7JFXͷݶք class DetailActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?)
{ super.onCreate(savedInstanceState) setContentView(R.layout.activity_detail) val composeView = findViewById<ComposeView>(R.id.compose_view) composeView.setContent { MyTheme { Scaffold { … } } } } } only with kotlin 110

؆୯ͳ7JFXΛ$VTUPN7JFXʹஔ͖׵͑Δ <?xml version="1.0" encoding="utf-8"?> <LinearLayout …> <TextView android:id="@+id/title_view" … />
<net.yanzm.myapplication.DetailActivityComposeView android:id="@+id/compose_view" … /> </LinearLayout> 111

@Composable fun DetailContent( title: String, ) { Text( text =
title, … ) } @Preview @Composable private fun Preview() { MyTheme { Surface { DetailContent( title = "title", ) } } } 112

class DetailActivityComposeView @JvmOverloads constructor( … ) : AbstractComposeView(context, attrs, defStyleAttr)
{ var title by mutableStateOf("") @Composable override fun Content() { MyTheme { Surface { DetailContent( title = title, ) } } } } 113

public class DetailActivity extends AppCompatActivity { private TextView titleView; private
DetailActivityComposeView composeView; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { … titleView = findViewById(R.id.title_view); composeView = findViewById(R.id.compose_view); } private void update() { titleView.setText(…); composeView.setTitle(…); } } 114

$PNQPTF΁ͷҠߦεςοϓ "CTUSBDU$PNQPTF7JFXΛܧঝͨ͠$VTUPN7JFXΛ࡞Δ ؆୯ͳ7JFXΛ$VTUPN7JFXʹஔ͖׵͑Δ ྡ઀͢Δ7JFXΛ$VTUPN7JFXʹऔΓࠐΉ શͯͷ7JFX͕औΓࠐ·ΕΔ·ͰεςοϓΛ܁Γฦ͢ 115

3FDZDMFS7JFXˠ$PNQPTF

3FDZDMFS7JFXˠ$PNQPTF JUFNMBZPVUJO3FDZDMFS7JFXˠ$PNQPTF 3FDZDMFS7JFXˠ-B[Z$PMVNO-B[Z3PX 117

JUFNMBZPVUJO3FDZDMFS7JFXˠ$PNQPTF 7JFX)PMEFSͷϦϑΝΫλϦϯά 7JFX)PMEFSˠ$PNQPTF 7JFX)PMEFSͷϨΠΞ΢τʹରԠ͢ΔDPNQPTBCMFΛ࡞Δ ͷDPNQPTBCMFΛར༻͢Δ$VTUPN7JFXΛ "CTUSBDU$PNQPTF7JFXͰ࡞Δ
ͷ$VTUPN7JFXΛ7JFX)PMEFSͰ࢖͏ શͯͷ7JFX)PMEFSʹରͯ͠εςοϓΛߦ͏ 118

7JFX)PMEFSͷϦϑΝΫλϦϯά w ੜ੒ϝιου w CJOEϝιου 119

public class ItemViewHolder extends RecyclerView.ViewHolder { … public static ItemViewHolder
create(@NonNull ViewGroup parent) { View view = LayoutInflater.from(parent.getContext()) .inflate(R.layout.list_item, parent, false); return new ItemViewHolder(view); } } public class ItemAdapter extends ListAdapter<Item, ItemViewHolder> { … @NonNull @Override public ItemViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) return ItemViewHolder.create(parent); } } 120

public class ItemViewHolder extends RecyclerView.ViewHolder { private final TextView titleView;
… public void bind(@NonNull String iconUrl, @NonNull String title) { … titleView.setText(title); } … } public class ItemAdapter extends ListAdapter<Item, ItemViewHolder> { … @Override public void onBindViewHolder(@NonNull ItemViewHolder holder, int position) { Item item = getItem(position); holder.bind(item.iconUrl, item.title); } } 121

7JFX)PMEFSʹରԠ͢ΔDPNQPTBCMFΛ࡞Δ @Composable fun ItemContent( iconUrl: String, title: String, modifier: Modifier
= Modifier ) { Row(…) { AsyncImage( model = iconUrl, contentDescription = null, modifier = Modifier.size(40.dp) ) Text( text = title, … ) } } 122

"CTUSBDU$PNQPTF7JFXͰ$VTUPN7JFXΛ࡞Δ class ItemView @JvmOverloads constructor( … ) : AbstractComposeView(context, attrs,
defStyleAttr) { var iconUrl by mutableStateOf("") var title by mutableStateOf("") @Composable override fun Content() { MyTheme { Surface { ItemContent( iconUrl = iconUrl, title = title, ) } } } } 123

7JFX)PMEFSͰ$VTUPN7JFXΛ࢖͏ public class ItemViewHolder extends RecyclerView.ViewHolder { private final ItemView
itemView; private ItemViewHolder(@NonNull ItemView itemView) { super(itemView); this.itemView = itemView; } public void bind(@NonNull String iconUrl, @NonNull String title) { itemView.setIconUrl(iconUrl); itemView.setTitle(title); } public static ItemViewHolder create(@NonNull ViewGroup parent) { return new ItemViewHolder(new ItemView(parent.getContext())); } } 124

3FDZDMFS7JFXˠ-B[Z$PMVNO-B[Z3PX 3FDZDMFS7JFXʹରԠ͢ΔDPNQPTBCMFΛ࡞Δʢ-B[Z$PMVNO-B[Z3PX ͷDPNQPTBCMFΛར༻͢Δ$VTUPN7JFXΛ"CTUSBDU$PNQPTF7JFX Ͱ࡞Δ "DUJWJUZ'SBHNFOUͰͷDPNQPTBCMFΛ࢖͏ 125

3FDZDMFS7JFXʹରԠ͢ΔDPNQPTBCMFΛ༻ҙ @Composable fun ItemList( items: List<Item> ) { LazyColumn {
items( items = items, key = { it.id.value }, contentType = { "item" } ) { item -> ItemContent( iconUrl = item.iconUrl, title = item.title ) } } } 126

"CTUSBDU$PNQPTF7JFXͰ$VTUPN7JFXΛ࡞Δ class ItemListView @JvmOverloads constructor( … ) : AbstractComposeView(context, attrs,
defStyleAttr) { var items by mutableStateOf<List<Item>>(emptyList()) @Composable override fun Content() { MyTheme { Surface { ItemList(items) } } } } 127

"DUJWJUZ'SBHNFOUͰ$VTUPN7JFXΛ࢖͏ <?xml version="1.0" encoding="utf-8"?> <LinearLayout …> … <androidx.recyclerview.widget.RecyclerView android:id="@+id/recycler_view" android:layout_width="match_parent"
android:layout_height="match_parent" /> <net.yanzm.myapplication.ItemListView android:id="@+id/item_list_view" android:layout_width="match_parent" android:layout_height="match_parent" /> </LinearLayout> 128

"DUJWJUZ'SBHNFOUͰ$VTUPN7JFXΛ࢖͏ public class MainActivity extends AppCompatActivity { private RecyclerView recyclerView;
private ItemAdapter adapter; private ItemListView itemListView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); recyclerView = findViewById(R.id.recycler_view); itemListView = findViewById(R.id.item_list_view); } … private void update(List<Item> items) { adapter.submitList(items); itemListView.setItems(items); } } 129

·ͱΊ

·ͱΊ w "OESPJEͷڞ௨ͷ஌ࣝͱਓؒͷೝ஌ͷݶքΛ׆༻ͯ͠ɺϓϩδΣΫτ͕ΑΓ Θ͔Γ΍͘͢ͳΔΑ͏ͳϦϑΝΫλϦϯάΛ͢Δ w ϦϑΝΫλϦϯάͷॱ൪͕ॏཁɺςετͰ͖Δ຤୺෦෼͔Β͸͡ΊΔ w "CTUSBDU$PNQPTF7JFXΛܧঝͨ͠$VTUPN7JFXΛ׆༻͠ɺஈ֊తʹ DPNQPTFԽ͍ͯ͘͠ 131

5IBOLZPV 132

アプリをリリースできる状態に保ったまま 段階的にリファクタリングするための 戦略と戦術 / S...

アプリをリリースできる状態に保ったまま 段階的にリファクタリングするための 戦略と戦術 / Strategies and tactics for incremental refactoring

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アプリをリリースできる状態に保ったまま段階的にリファクタリングするための戦略と戦術 / S...

アプリをリリースできる状態に保ったまま段階的にリファクタリングするための戦略と戦術 / Strategies and tactics for incremental refactoring