Generating code in APs and compiling Java files is mostly working

Author: tschuchortdev

build.gradle

@@ -48,7 +48,8 @@ dependencies {
     testImplementation "org.mockito:mockito-core:2.23.4"
     testImplementation "com.nhaarman.mockitokotlin2:mockito-kotlin:2.0.0"
 
-    compile "me.eugeniomarletti.kotlin.metadata:kotlin-metadata:1.4.0"
+    testCompile "me.eugeniomarletti.kotlin.metadata:kotlin-metadata:1.4.0"
+    testCompile 'com.squareup:kotlinpoet:1.0.0-RC1'
 
     testImplementation "com.squareup.okio:okio:2.1.0"
     testImplementation 'io.github.classgraph:classgraph:4.6.10'

src/test/kotlin/JavacUtils.kt

@@ -0,0 +1,58 @@
+package com.tschuchort.compiletest
+
+import org.jetbrains.kotlin.incremental.isJavaFile
+import java.io.*
+import java.net.URI
+import java.net.URL
+import java.nio.charset.Charset
+import javax.tools.JavaCompiler
+import javax.tools.JavaFileObject
+import javax.tools.SimpleJavaFileObject
+
+/**
+ * A [JavaFileObject] created from a source [File].
+ *
+ * Used for interfacing with javac ([JavaCompiler]).
+ */
+internal class FileJavaFileObject(val sourceFile: File, val charset: Charset = Charset.defaultCharset())
+    : SimpleJavaFileObject(sourceFile.toURI(), deduceKind(sourceFile.toURI())) {
+
+    init {
+        require(sourceFile.isFile)
+        require(sourceFile.canRead())
+    }
+
+    companion object {
+        private fun deduceKind(uri: URI): JavaFileObject.Kind
+            = JavaFileObject.Kind.values().firstOrNull {
+                uri.path.endsWith(it.extension, ignoreCase = true)
+            } ?: JavaFileObject.Kind.OTHER
+    }
+
+    override fun openInputStream(): InputStream = sourceFile.inputStream()
+
+    override fun getCharContent(ignoreEncodingErrors: Boolean): CharSequence
+            = sourceFile.readText(charset)
+}
+
+/**
+ * A [JavaFileObject] created from a [String].
+ *
+ * Used for interfacing with javac ([JavaCompiler]).
+ */
+internal class StringJavaFileObject(className: String, private val contents: String)
+    : SimpleJavaFileObject(
+    URI.create("string:///" + className.replace('.', '/') + JavaFileObject.Kind.SOURCE.extension),
+    JavaFileObject.Kind.SOURCE
+){
+    private var _lastModified = System.currentTimeMillis()
+
+    override fun getCharContent(ignoreEncodingErrors: Boolean): CharSequence = contents
+
+    override fun openInputStream(): InputStream
+            = ByteArrayInputStream(contents.toByteArray(Charset.defaultCharset()))
+
+    override fun openReader(ignoreEncodingErrors: Boolean): Reader = StringReader(contents)
+
+    override fun getLastModified(): Long = _lastModified
+}