Add unit tests for ksp processor

gradle/libs.versions.toml

@@ -6,6 +6,7 @@ compose = "1.6.8"
 coroutines = "1.8.1"
 javaTarget = "11"
 kotlin = "2.0.20"
+kotlinCompileTesting = "1.5.0"
 kotlinPoet = "1.18.1"
 ksp = "2.0.20-1.0.24"
 layoutlib = "14.0.9"
@@ -32,6 +33,8 @@ guava = { module = "com.google.guava:guava", version = "33.3.0-jre" }
 kotlin-bom = { module = "org.jetbrains.kotlin:kotlin-bom", version.ref = "kotlin" }
 kotlinpoet = { module = "com.squareup:kotlinpoet", version.ref = "kotlinPoet" }
 kotlinpoet-ksp = { module = "com.squareup:kotlinpoet-ksp", version.ref = "kotlinPoet" }
+kotlin-compile-testing = { module = "com.github.tschuchortdev:kotlin-compile-testing", version.ref = "kotlinCompileTesting" }
+kotlin-compile-testing-ksp = { module = "com.github.tschuchortdev:kotlin-compile-testing-ksp", version.ref = "kotlinCompileTesting" }
 kotlinx-coroutines-android = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-android", version.ref = "coroutines" }
 kotlinx-coroutines-test = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-test", version.ref = "coroutines" }
 

paparazzi-preview-processor/build.gradle

@@ -5,4 +5,9 @@ dependencies {
   implementation libs.kotlinpoet
   implementation libs.kotlinpoet.ksp
   implementation libs.ksp
+
+  testImplementation libs.junit
+  testImplementation libs.truth
+  testImplementation libs.kotlin.compile.testing
+  testImplementation libs.kotlin.compile.testing.ksp
 }

paparazzi-preview-processor/src/main/java/app/cash/paparazzi/preview/processor/PaparazziPoet.kt

@@ -9,7 +9,6 @@ import com.squareup.kotlinpoet.FileSpec
 import com.squareup.kotlinpoet.buildCodeBlock
 
 internal object PaparazziPoet {
-
   fun buildFiles(
     functions: Sequence<KSFunctionDeclaration>,
     isTest: Boolean,
@@ -50,15 +49,13 @@ internal object PaparazziPoet {
 
               when {
                 visibilityCheck.isPrivate -> addError(
-                  visibilityCheck = visibilityCheck,
                   function = func,
                   snapshotName = snapshotName,
                   buildErrorMessage = {
                     "$it is private. Make it internal or public to generate a snapshot."
                   }
                 )
                 previewParam != null -> addError(
-                  visibilityCheck = visibilityCheck,
                   function = func,
                   snapshotName = snapshotName,
                   buildErrorMessage = {
@@ -87,24 +84,21 @@ internal object PaparazziPoet {
     block: (KSFunctionDeclaration, KSValueParameter?) -> Unit
   ) =
     flatMap { func ->
-      val previewParam = func.previewParam()
-      func.findDistinctPreviews()
+      val previewParam = func.parameters.firstOrNull { param ->
+        param.annotations.any { it.isPreviewParameter() }
+      }
+      func.annotations.findPreviews().distinct()
         .map { Pair(func, previewParam) }
     }.forEach { (func, previewParam) ->
       block(func, previewParam)
     }
 
   private fun CodeBlock.Builder.addError(
-    visibilityCheck: VisibilityCheck,
     function: KSFunctionDeclaration,
     snapshotName: String,
     buildErrorMessage: (String?) -> String
   ) {
-    val qualifiedName = if (visibilityCheck.isFunctionPrivate) {
-      function.qualifiedName?.asString()
-    } else {
-      null
-    }
+    val qualifiedName = function.qualifiedName?.asString()
 
     addStatement("%L.PaparazziPreviewData.Error(", PACKAGE_NAME)
     indent()
@@ -114,18 +108,6 @@ internal object PaparazziPoet {
     addStatement("),")
   }
 
-  private fun CodeBlock.Builder.addProvider(
-    function: KSFunctionDeclaration,
-    snapshotName: String
-  ) {
-    addStatement("%L.PaparazziPreviewData.Provider(", PACKAGE_NAME)
-    indent()
-    addStatement("snapshotName = %S,", snapshotName)
-    addStatement("composable = { %L(it) },", function.qualifiedName?.asString())
-    unindent()
-    addStatement("),")
-  }
-
   private fun CodeBlock.Builder.addDefault(
     function: KSFunctionDeclaration,
     snapshotName: String

paparazzi-preview-processor/src/main/java/app/cash/paparazzi/preview/processor/PreviewProcessor.kt

@@ -20,11 +20,13 @@ public class PreviewProcessor(
   private val environment: SymbolProcessorEnvironment
 ) : SymbolProcessor {
 
-  private var invoked = false
-
   override fun process(resolver: Resolver): List<KSAnnotated> {
-    if (invoked) return emptyList()
-    invoked = true
+    // Due to codgen and multi-round processing of ksp
+    // https://kotlinlang.org/docs/ksp-multi-round.html
+    if (resolver.getNewFiles().any { it.fileName.contains("PaparazziPreviews.kt") }) {
+      "Skipping subsequent run due to PaparazziPreviews.kt already created and caused ksp re-run".log()
+      return emptyList()
+    }
 
     val allFiles = resolver.getAllFiles().toList()
     if (allFiles.isEmpty()) return emptyList()
@@ -41,7 +43,7 @@ public class PreviewProcessor(
       .also { functions ->
         "found ${functions.count()} function(s)".log()
         PaparazziPoet.buildFiles(functions, isTestSourceSet, env).forEach { file ->
-          "writing file: ${file.packageName}.${file.name}".log()
+          "writing file: ${file.packageName}.${file.name}.kt".log()
           file.writeTo(environment.codeGenerator, dependencies)
         }
       }

paparazzi-preview-processor/src/main/java/app/cash/paparazzi/preview/processor/Utils.kt

@@ -35,12 +35,6 @@ internal fun Sequence<KSAnnotation>.findPreviews(stack: Set<KSAnnotation> = setO
   return direct.plus(indirect)
 }
 
-internal fun KSFunctionDeclaration.findDistinctPreviews() = annotations.findPreviews().distinct()
-
-internal fun KSFunctionDeclaration.previewParam() = parameters.firstOrNull { param ->
-  param.annotations.any { it.isPreviewParameter() }
-}
-
 internal data class EnvironmentOptions(
   val namespace: String
 )

paparazzi-preview-processor/src/test/java/app/cash/paparazzi/preview/processor/KspCompileResult.kt

@@ -0,0 +1,9 @@
+package app.cash.paparazzi.preview.processor
+
+import com.tschuchort.compiletesting.KotlinCompilation
+import java.io.File
+
+data class KspCompileResult(
+  val result: KotlinCompilation.Result,
+  val generatedFiles: List<File>
+)