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November 02, 2022
Isolated Development
Ralf Wondratschek
@vRallev
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Challenges in 2018
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Challenges in 2018: lines of code growth
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Challenges in 2018: lines of code growth
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Challenges in 2018: build times are growing
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:hairball
:app2
:app1
:lib1 :lib2
Challenges in 2018: module structure
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:apps
:feature
:common
:api
Challenges in 2018: module structure
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:hairball
:app2
:app1
:lib1 :lib2
Challenges in 2018: multiple apps with different flavors
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:hairball
:app2
:app1
:lib1 :lib2
Challenges in 2018: multiple apps with different flavors
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No content
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https://bit.ly/3D8SsUl
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Dependency inversion
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class Feature(s: LoginStrategy) interface LoginStrategy
class SmsLoginStrategy() : LoginStrategy
Dependency inversion
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class SmsLoginStrategy @Inject constructor(
private val helper: Helper,
private val helper: Helper1,
private val helper: Helper2,
private val helper: Helper3,
private val helper: Helper4,
private val helper: Helper5,
private val helper: Helper6,
private val helper: Helper7,
private val helper: Helper8
) : LoginStrategy
Dependency inversion
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dependencies {
api project(':helper1')
api project(':helper2')
api project(':helper3')
api project(':helper4')
api project(':helper5')
api project(':helper6')
api project(':helper7')
api project(':helper8')
}
Dependency inversion
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dependencies {
api project(':login-strategy')
}
Dependency inversion
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Module Structure
:public
:impl
:impl-wiring
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:login-strategy
Module Structure
:public
:impl
:impl-wiring
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Module Structure
:login-strategy:public
:login-strategy:impl
:login-strategy:impl-wiring
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Module Structure
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:login-strategy
Module Structure
:public
:impl
:impl-wiring
:feature
:public
:impl
:impl-wiring
X
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Development Apps
:public
:impl
:impl-wiring
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Development Apps
:public
:impl
:impl-wiring
:demo
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Development Apps
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Development Apps
● Install a feature with an isolated application on the device
○ Launch the feature directly
○ Shorter build times
● Easy way to experiment and merge code
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:login-screen
Development Apps
:public
:impl
:impl-wiring
:demo
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:login-screen
Development Apps
:public
:impl
:impl-wiring
:demo
:development-app
:public
:impl
:impl-wiring
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:login-screen
Development Apps
:public
:impl
:impl-wiring
:demo
:development-app
:public
:impl
:impl-wiring
:ui-engine
:public
:impl
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:login-screen
Development Apps
:public
:impl
:impl-wiring
:demo
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:login-screen
Development Apps
:public
:impl
:impl-wiring
:demo
:account-screen
:public
:impl
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https://square.github.io/workflow/
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:account-screen:public
interface AccountScreenWorkflow : Workflow>
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:account-screen:impl
class RealAccountScreenWorkflow @Inject constructor(
…
) : AccountScreenWorkflow
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:login-screen:public
interface LoginScreenWorkflow : Workflow>
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:login-screen:impl
class RealLoginScreenWorkflow @Inject constructor(
private val accountScreenWorkflow: Provider
) : LoginScreenWorkflow
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:login-screen
Development Apps
:public
:impl
:impl-wiring
:demo
:account-screen
:public
:impl
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:login-screen
Development Apps
:public
:impl
:impl-wiring
:demo
:account-screen
:public
:impl
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:login-screen
Development Apps
:public
:impl
:impl-wiring
:demo
:account-screen
:public
:fake
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:account-screen:fake
class FakeAccountScreenWorkflow @Inject constructor() : AccountScreenWorkflow {
// ...
}
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Module Structure
:public
:impl
:impl-wiring
:demo
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Module Structure
:public
:impl
:impl-wiring
:demo
:fake
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:login-screen:demo
android {
defaultConfig {
applicationId "com.squareup.sample.login.screen.demo"
}
}
dependencies {
// …
implementation project(':account-screen:fake')
implementation project(':development-app:impl-wiring)
}
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:login-screen:demo
@DevelopmentAppComponent
class DemoLoginApp : DevelopmentApplication()
@Module
@ContributesTo(ActivityScope::class)
object DemoLoginMainActivityModule {
@Provides
fun provideFeatureWorkflowProvider(
workflow: LoginScreenWorkflow
): FeatureProvider =
FeatureWorkflowProvider(
workflow = workflow,
props = Unit,
)
}
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:login-screen:demo
@DevelopmentAppComponent
class DemoLoginApp : DevelopmentApplication()
@Module
@ContributesTo(ActivityScope::class)
object DemoLoginMainActivityModule {
@Provides
fun provideFeatureWorkflowProvider(
workflow: LoginScreenWorkflow
): FeatureProvider =
FeatureWorkflowProvider(
workflow = workflow,
props = Unit,
)
}
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:login-screen:demo
@DevelopmentAppComponent
class DemoLoginApp : DevelopmentApplication()
@Module
@ContributesTo(ActivityScope::class)
object DemoLoginMainActivityModule {
@Provides
fun provideFeatureWorkflowProvider(
workflow: LoginScreenWorkflow
): FeatureProvider =
FeatureWorkflowProvider(
workflow = workflow,
props = Unit,
)
}
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● Part of the development apps
→ Faster builds
→ Tend to be very stable
→ More build cache hits
→ Automatic test shardening
● Integration tests live in the final applications
→ Test robots are shared across all apps
UI Tests
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Mechanisms
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plugins {
id 'com.android.library
id 'org.jetbrains.kotlin.android'
id 'org.jetbrains.kotlin.kapt'
id 'com.squareup.anvil'
}
dependencies {
api project(':account-screen:public')
...
}
tasks.withType(KotlinCompile).configureEach {
kotlinOptions {
jvmTarget = JavaVersion.VERSION_11
}
}
Mechanisms: module structure through convention plugins
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// :login-screen:impl
plugins {
id 'com.squareup.android.lib
}
// :login-screen:demo
plugins {
id 'com.squareup.demo-app
}
Mechanisms: module structure through convention plugins
https://developer.squareup.com/blog/herding-elephants/
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class NoImplDependencyModuleCheck : ModuleCheck {
override fun runCheck(project: Project) {
…
fail(
"No :impl dependency is allowed. Requested: " +
"${implDependencies.joinToString { it.dependencyName }} in project: $project."
)
}
}
Mechanisms: module structure enforced through Lint rules
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Mechanisms: library generator
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Mechanisms: library generator
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Mechanisms: library generator
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Mechanisms: design patterns & frameworks
● Workflow
→ Composition was key
→ https://square.github.io/workflow/
● Dependency inversion
→ Enforced through the module structure
● Dependency Injection
→ Anvil: https://github.com/square/anvil/
→ Dagger 2: https://dagger.dev/
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class RealLoginScreenWorkflow @Inject constructor(
private val accountScreenWorkflow: Provider
) : LoginScreenWorkflow
Mechanisms: design patterns & frameworks: Anvil
https://github.com/square/anvil/
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class RealLoginScreenWorkflow @Inject constructor(
private val accountScreenWorkflow: Provider
) : LoginScreenWorkflow
@Module
abstract class LoginScreenWorkflowModule {
@Binds abstract fun bindLoginScreenWorkflow(
workflow: RealLoginScreenWorkflow
) : LoginScreenWorkflow
}
Mechanisms: design patterns & frameworks: Anvil
https://github.com/square/anvil/
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class RealLoginScreenWorkflow @Inject constructor(
private val accountScreenWorkflow: Provider
) : LoginScreenWorkflow
@Module
abstract class LoginScreenWorkflowModule {
@Binds abstract fun bindLoginScreenWorkflow(
workflow: RealLoginScreenWorkflow
) : LoginScreenWorkflow
}
@Component(
modules = {
LoginScreenWorkflowModule::class,
}
)
interface AppComponent
Mechanisms: design patterns & frameworks: Anvil
https://github.com/square/anvil/
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@ContributesBinding(ActivityScope::class)
class RealLoginScreenWorkflow @Inject constructor(
private val accountScreenWorkflow: Provider
) : LoginScreenWorkflow
Mechanisms: design patterns & frameworks: Anvil
https://github.com/square/anvil/
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@ContributesBinding(ActivityScope::class)
class RealLoginScreenWorkflow @Inject constructor(
private val accountScreenWorkflow: Provider
) : LoginScreenWorkflow
Mechanisms: design patterns & frameworks: Anvil
https://github.com/square/anvil/
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@DevelopmentAppComponent
class DemoLoginApp : DevelopmentApplication()
@Module
@ContributesTo(ActivityScope::class)
object DemoLoginMainActivityModule {
@Provides
fun provideFeatureWorkflowProvider(
workflow: LoginScreenWorkflow
): FeatureProvider =
FeatureWorkflowProvider(
workflow = workflow,
props = Unit,
)
}
Mechanisms: design patterns & frameworks: Anvil
https://github.com/square/anvil/
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@DevelopmentAppComponent
class DemoLoginApp : DevelopmentApplication()
@Module
@ContributesTo(ActivityScope::class)
object DemoLoginMainActivityModule {
@Provides
fun provideFeatureWorkflowProvider(
workflow: LoginScreenWorkflow
): FeatureProvider =
FeatureWorkflowProvider(
workflow = workflow,
props = Unit,
)
}
Mechanisms: design patterns & frameworks: Anvil
https://github.com/square/anvil/
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https://bit.ly/3WbPHdm
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Mechanisms: design patterns & frameworks: Anvil
https://bit.ly/3WbPHdm
Try to build :demo module
Add missing dependencies
to build.gradle file
Sync :demo module in
Android Studio
Add Dagger modules to
Dagger components
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Mechanisms: design patterns & frameworks: Anvil
https://bit.ly/3WbPHdm
Try to build :demo module
Add missing dependencies
to build.gradle file
Sync :demo module in
Android Studio
Add Dagger modules to
Dagger components
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Mechanisms: dashboards
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Mechanisms: dashboards
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Mechanisms: dashboards
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Mechanisms: dashboards
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Mechanisms: dashboards
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Mechanisms: dashboards
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Mechanisms: dashboards
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Mechanisms: dashboards
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Mechanisms: benchmarks
https://developer.squareup.com/blog/measure-measure-measure/
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Mechanisms: benchmarks
https://developer.squareup.com/blog/measure-measure-measure/
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Mechanisms: benchmarks
https://developer.squareup.com/blog/measure-measure-measure/
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Mechanisms: migrations
● We were a small team and relied on the help of feature teams to contribute to common goals
→ Legacy module migration
→ Adopt Anvil
→ Extract UI tests into :demo apps
https://www.droidcon.com/2022/09/29/migration-without-migraines-automatic-migration-at-scale/
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Challenges
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Challenges: module count
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Solution:
● Convention plugins
● Benchmarks
● Anvil
● Configuration caching
● Partial IDE sync
→ https://github.com/dropbox/focus
Challenges: module count
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Legacy modules break our dependency rules
Solution:
● Finish migration
Challenges: legacy modules
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Anti-pattern
Challenges: granular modules
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Challenges: granular modules
:login-screen
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Challenges: granular modules
:login-screen
:feature-a
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Challenges: granular modules
:login-screen
:feature-a :feature-b
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Challenges: granular modules
:login-screen
:feature-a :feature-b
:login-strategy
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Challenges: granular modules
:login-screen
:public
:impl
:impl-wiring
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Challenges: granular modules
:login-screen
:public
:impl-a
:impl-a-wiring
:impl-b
:impl-b-wiring
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Challenges: granular modules
:login-screen
:public
:impl-a
:impl-a-wiring
:impl-b :impl-c
:impl-b-wiring :impl-c-wiring
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Challenges: development app shell
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Challenges: extract UI tests
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November 02, 2022
Isolated Development
Ralf Wondratschek
@vRallev