Don't forget that snapshot tests must start with 'test'

build-support-ksp-processor/build.gradle.kts

@@ -0,0 +1,7 @@
+plugins {
+  kotlin("jvm")
+}
+
+dependencies {
+  implementation(libs.kotlin.kspApi)
+}

build-support-ksp-processor/src/main/kotlin/app/cash/redwood/buildsupportksp/RedwoodSymbolProcessor.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2024 Square, Inc.
+ *
+ * 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 app.cash.redwood.buildsupportksp
+
+import com.google.devtools.ksp.processing.Resolver
+import com.google.devtools.ksp.processing.SymbolProcessor
+import com.google.devtools.ksp.processing.SymbolProcessorEnvironment
+import com.google.devtools.ksp.symbol.KSAnnotated
+
+class RedwoodSymbolProcessor(
+  private val environment: SymbolProcessorEnvironment,
+) : SymbolProcessor {
+  override fun process(resolver: Resolver): List<KSAnnotated> {
+    SnapshotTestProcessor(environment).process(resolver)
+
+    return listOf() // No more rounds of annotation processing.
+  }
+}

build-support-ksp-processor/src/main/kotlin/app/cash/redwood/buildsupportksp/RedwoodSymbolProcessorProvider.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2024 Square, Inc.
+ *
+ * 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 app.cash.redwood.buildsupportksp
+
+import com.google.devtools.ksp.processing.SymbolProcessorEnvironment
+import com.google.devtools.ksp.processing.SymbolProcessorProvider
+
+class RedwoodSymbolProcessorProvider : SymbolProcessorProvider {
+  override fun create(environment: SymbolProcessorEnvironment) =
+    RedwoodSymbolProcessor(environment)
+}

build-support-ksp-processor/src/main/kotlin/app/cash/redwood/buildsupportksp/SnapshotTestProcessor.kt

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2024 Square, Inc.
+ *
+ * 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 app.cash.redwood.buildsupportksp
+
+import com.google.devtools.ksp.processing.Resolver
+import com.google.devtools.ksp.processing.SymbolProcessorEnvironment
+import com.google.devtools.ksp.symbol.KSFunctionDeclaration
+
+/** Confirm all snapshot `@Test` functions also have names starting with `test`. */
+internal class SnapshotTestProcessor(
+  private val environment: SymbolProcessorEnvironment,
+) {
+  fun process(resolver: Resolver) {
+    // Only run on the first round.
+    if (!resolver.getNewFiles().iterator().hasNext()) return
+
+    checkAllTests(resolver)
+  }
+
+  private fun checkAllTests(resolver: Resolver) {
+    for (symbol in resolver.getSymbolsWithAnnotation("org.junit.Test")) {
+      when {
+        symbol !is KSFunctionDeclaration -> {
+          environment.logger.info("Unexpected @Test", symbol)
+        }
+
+        !symbol.simpleName.asString().startsWith("test") -> {
+          environment.logger.error("Expected @Test to start with 'test'", symbol)
+        }
+      }
+    }
+  }
+}

build-support-ksp-processor/src/main/resources/META-INF/services/com.google.devtools.ksp.processing.SymbolProcessorProvider

@@ -0,0 +1 @@
+app.cash.redwood.buildsupportksp.RedwoodSymbolProcessorProvider

build-support/build.gradle

@@ -28,6 +28,7 @@ apply plugin: 'com.android.lint'
 dependencies {
   compileOnly gradleApi()
   implementation libs.kotlin.gradlePlugin
+  implementation libs.kotlin.kspGradlePlugin
   implementation libs.gradleMavenPublishPlugin
   implementation libs.dokkaPlugin
   implementation libs.spotlessPlugin

build-support/src/main/kotlin/app/cash/redwood/buildsupport/RedwoodBuildExtension.kt

@@ -46,6 +46,9 @@ interface RedwoodBuildExtension {
   fun TaskContainer.generateComposeHelpers(packageName: String): TaskProvider<CopyPastaTask>
 
   fun TaskContainer.generateFlexboxHelpers(packageName: String): TaskProvider<CopyPastaTask>
+
+  /** Confirm all snapshot `@Test` functions also have names starting with `test`. */
+  fun sharedSnapshotTests()
 }
 
 enum class TargetGroup {

build-support/src/main/kotlin/app/cash/redwood/buildsupport/RedwoodBuildPlugin.kt

@@ -647,6 +647,11 @@ private class RedwoodBuildExtensionImpl(private val project: Project) : RedwoodB
       it.packageName.set(packageName)
     }
   }
+
+  override fun sharedSnapshotTests() {
+    project.plugins.apply("com.google.devtools.ksp")
+    project.dependencies.add("kspJvm", project.project(":build-support-ksp-processor"))
+  }
 }
 
 private val ziplineAttribute = Attribute.of("zipline", String::class.java)

gradle/libs.versions.toml

@@ -5,6 +5,7 @@ kotlinx-serialization = "1.7.3"
 androidx-activity = "1.9.2"
 androidx-compose-ui = "1.7.2"
 jbCompose = "1.6.11"
+ksp = "2.0.20-1.0.25"
 lint = "31.6.1"
 paparazzi = "1.3.2"
 zipline = "1.17.0"
@@ -16,6 +17,8 @@ kotlin-compiler = { module = "org.jetbrains.kotlin:kotlin-compiler", version.ref
 kotlin-compilerEmbeddable = { module = "org.jetbrains.kotlin:kotlin-compiler-embeddable", version.ref = "kotlin" }
 kotlin-composePlugin = { module = "org.jetbrains.kotlin:compose-compiler-gradle-plugin", version.ref = "kotlin" }
 kotlin-gradlePlugin = { module = "org.jetbrains.kotlin:kotlin-gradle-plugin", version.ref = "kotlin" }
+kotlin-kspApi = { module = "com.google.devtools.ksp:symbol-processing-api", version.ref = "ksp" }
+kotlin-kspGradlePlugin = { module = "com.google.devtools.ksp:symbol-processing-gradle-plugin", version.ref = "ksp" }
 kotlin-serializationPlugin = { module = "org.jetbrains.kotlin:kotlin-serialization", version.ref = "kotlin" }
 kotlin-reflect = { module = "org.jetbrains.kotlin:kotlin-reflect", version.ref = "kotlin" }
 kotlin-test = { module = "org.jetbrains.kotlin:kotlin-test", version.ref = "kotlin" }

redwood-layout-shared-test/build.gradle

@@ -2,6 +2,7 @@ import static app.cash.redwood.buildsupport.TargetGroup.ToolkitAllWithoutAndroid
 
 redwoodBuild {
   targets(ToolkitAllWithoutAndroid)
+  sharedSnapshotTests()
 }
 
 kotlin {

redwood-layout-shared-test/src/commonMain/kotlin/app/cash/redwood/layout/AbstractFlexContainerTest.kt

@@ -245,7 +245,7 @@ abstract class AbstractFlexContainerTest<T : Any> {
     snapshotter(container.value).snapshot()
   }
 
-  @Test fun columnWithUpdatedCrossAxisAlignment() {
+  @Test fun testColumnWithUpdatedCrossAxisAlignment() {
     val container = flexContainer(FlexDirection.Column)
     val snapshotter = snapshotter(container.value)
     container.width(Constraint.Fill)

redwood-lazylayout-shared-test/build.gradle

@@ -2,6 +2,7 @@ import static app.cash.redwood.buildsupport.TargetGroup.ToolkitAllWithoutAndroid
 
 redwoodBuild {
   targets(ToolkitAllWithoutAndroid)
+  sharedSnapshotTests()
 }
 
 kotlin {

redwood-widget-shared-test/build.gradle

@@ -2,6 +2,7 @@ import static app.cash.redwood.buildsupport.TargetGroup.ToolkitAllWithoutAndroid
 
 redwoodBuild {
   targets(ToolkitAllWithoutAndroid)
+  sharedSnapshotTests()
 }
 
 kotlin {

settings.gradle

@@ -43,6 +43,7 @@ enableFeaturePreview('TYPESAFE_PROJECT_ACCESSORS')
 
 rootProject.name = 'redwood'
 
+include ':build-support-ksp-processor'
 include ':redwood-bom'
 include ':redwood-compose'
 include ':redwood-composeui'