Report KSP logs in compilations (#95)

* Report KSP logs in compilations

Resolves #69. This is based on an implementation I've been using in my projects, and also works around internal access across modules via lesser-known suppression mechanism until kotlin finally finishes implementing friend-paths support in their gradle/IDE tooling.

* Add tests

* Remove unnecessary copy of MessageCollectorBasedKSPLogger

Co-authored-by: Thilo Schuchort <t.schuchort@googlemail.com>

Author: ZacSweers

core/src/main/kotlin/com/tschuchort/compiletesting/AbstractKotlinCompilation.kt

@@ -262,6 +262,8 @@ abstract class AbstractKotlinCompilation<A : CommonCompilerArguments> internal c
 
     protected fun warn(s: String) = internalMessageStream.println("warning: $s")
     protected fun error(s: String) = internalMessageStream.println("error: $s")
+
+    internal val internalMessageStreamAccess: PrintStream get() = internalMessageStream
 }
 
 internal fun kotlinDependencyRegex(prefix:String): Regex {

ksp/src/main/kotlin/com/tschuchort/compiletesting/Ksp.kt

@@ -160,12 +160,17 @@ private class KspCompileTestingComponentRegistrar(
                 it.mkdirs()
             }
         }.build()
-        // TODO: replace with KotlinCompilation.internalMessageStream
-        val registrar = KspTestExtension(
-            options, processors, MessageCollectorBasedKSPLogger(
-                PrintingMessageCollector(System.err, MessageRenderer.GRADLE_STYLE, compilation.verbose)
+
+        // Temporary until friend-paths is fully supported https://youtrack.jetbrains.com/issue/KT-34102
+        @Suppress("invisible_member")
+        val messageCollectorBasedKSPLogger = MessageCollectorBasedKSPLogger(
+            PrintingMessageCollector(
+                compilation.internalMessageStreamAccess,
+                MessageRenderer.GRADLE_STYLE,
+                compilation.verbose
             )
         )
+        val registrar = KspTestExtension(options, processors, messageCollectorBasedKSPLogger)
         AnalysisHandlerExtension.registerExtension(project, registrar)
     }
 }

ksp/src/test/kotlin/com/tschuchort/compiletesting/AbstractTestSymbolProcessor.kt

@@ -10,11 +10,13 @@ import com.google.devtools.ksp.processing.SymbolProcessor
  */
 internal open class AbstractTestSymbolProcessor : SymbolProcessor {
     protected lateinit var codeGenerator: CodeGenerator
+    protected lateinit var logger: KSPLogger
     override fun finish() {
     }
 
     override fun init(options: Map<String, String>, kotlinVersion: KotlinVersion, codeGenerator: CodeGenerator, logger: KSPLogger) {
         this.codeGenerator = codeGenerator
+        this.logger = logger
     }
 
     override fun process(resolver: Resolver) {

ksp/src/test/kotlin/com/tschuchort/compiletesting/KspTest.kt

@@ -178,6 +178,42 @@ class KspTest {
         }
     }
 
+    @Test
+    fun messagesAreReadable() {
+        val annotation = SourceFile.kotlin(
+            "TestAnnotation.kt", """
+            package foo.bar
+            annotation class TestAnnotation
+        """.trimIndent()
+        )
+        val targetClass = SourceFile.kotlin(
+            "AppCode.kt", """
+            package foo.bar
+            @TestAnnotation
+            class AppCode
+        """.trimIndent()
+        )
+        val processor = object : AbstractTestSymbolProcessor() {
+            override fun process(resolver: Resolver) {
+                logger.logging("This is a log message")
+                logger.info("This is an info message")
+                logger.warn("This is an warn message")
+                logger.error("This is an error message")
+                logger.exception(Throwable("This is a failure"))
+            }
+        }
+        val result = KotlinCompilation().apply {
+            sources = listOf(annotation, targetClass)
+            symbolProcessors = listOf(processor)
+        }.compile()
+        assertThat(result.exitCode).isEqualTo(ExitCode.OK)
+        assertThat(result.messages).contains("This is a log message")
+        assertThat(result.messages).contains("This is an info message")
+        assertThat(result.messages).contains("This is an warn message")
+        assertThat(result.messages).contains("This is an error message")
+        assertThat(result.messages).contains("This is a failure")
+    }
+
     companion object {
         private val DUMMY_KOTLIN_SRC = SourceFile.kotlin(
             "foo.bar.Dummy.kt", """