Close in-memory repo, fix diff when no changes

build.gradle

@@ -26,12 +26,8 @@ repositories {
 antlr4.output = new File('src/main/java/com/netflix/java/refactor/aspectj')
 antlr4.extraArgs = ['-package', 'com.netflix.java.refactor.aspectj']
 
-// add antlr4 to classpath
 configurations {
     compile.extendsFrom antlr4
-}
-
-configurations {
     compile.extendsFrom compileShaded
 }
 

src/main/kotlin/com/netflix/java/refactor/InMemoryDiffEntry.kt

@@ -9,7 +9,7 @@ import java.io.ByteArrayOutputStream
 
 class InMemoryDiffEntry(filePath: String, old: String, new: String): DiffEntry() {
     private val repo = InMemoryRepository.Builder().build()
-
+    
     init {
         changeType = DiffEntry.ChangeType.MODIFY
         oldPath = filePath
@@ -22,13 +22,18 @@ class InMemoryDiffEntry(filePath: String, old: String, new: String): DiffEntry()
 
         oldMode = FileMode.REGULAR_FILE
         newMode = FileMode.REGULAR_FILE
+        repo.close()
     }
 
     val diff: String by lazy {
-        val patch = ByteArrayOutputStream()
-        val formatter = DiffFormatter(patch)
-        formatter.setRepository(repo)
-        formatter.format(this)
-        String(patch.toByteArray())
+        if(oldId == newId)
+            ""
+        else {
+            val patch = ByteArrayOutputStream()
+            val formatter = DiffFormatter(patch)
+            formatter.setRepository(repo)
+            formatter.format(this)
+            String(patch.toByteArray())
+        }
     }
 }

src/main/kotlin/com/netflix/java/refactor/JavaSource.kt

@@ -12,6 +12,7 @@ class JavaSource(internal val cu: CompilationUnit) {
 
     fun file() = cu.source()
     fun text() = String(Files.readAllBytes(cu.source()))
+
     fun classes() = cu.jcCompilationUnit.defs
             .filterIsInstance<JCTree.JCClassDecl>()
             .map { it.sym }

src/main/kotlin/com/netflix/java/refactor/JavaSourceDiff.kt

@@ -1,10 +1,7 @@
 package com.netflix.java.refactor
 
 class JavaSourceDiff(private val source: JavaSource) {
-    val before = source.text()
+    private val before = source.text()
 
-    fun gitStylePatch(): String {
-        val after = source.text()
-        return InMemoryDiffEntry(source.file().toString(), before, after).diff
-    }
+    fun gitStylePatch() = InMemoryDiffEntry(source.file().toString(), before, source.text()).diff  
 }

src/main/kotlin/com/netflix/java/refactor/RefactorTransaction.kt

@@ -80,7 +80,7 @@ class RefactorTransaction(val refactorer: JavaSource) {
                 }
 
                 Files.write(refactorer.file(), source.toByteArray(), StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING)
-
+//                refactorer.file().toFile().writeText(source)
             } catch(t: Throwable) {
                 // TODO how can we throw a better exception?
                 t.printStackTrace()

src/test/kotlin/com/netflix/java/refactor/InMemoryDiffEntryTest.kt

@@ -6,7 +6,16 @@ import org.junit.Assert.assertEquals
 class InMemoryDiffEntryTest {
 
     @Test
-    fun diffTest() {
+    fun idempotent() {
+        val diff = InMemoryDiffEntry("com/netflix/MyJavaClass.java",
+                "public class A {}",
+                "public class A {}")
+
+        assertEquals("", diff.diff)
+    }
+
+    @Test
+    fun singleLineChange() {
         val diff = InMemoryDiffEntry("com/netflix/MyJavaClass.java",
             """
                 |public void test() {