From 2a75f322fd4a3f72b7c64d402efa94aa88ac6f3c Mon Sep 17 00:00:00 2001
From: Evgeny Mandrikov <mandrikov@gmail.com>
Date: Sun, 21 Feb 2021 11:30:58 +0100
Subject: [PATCH] (WIP) add unit test

---
 .../filter/KotlinWhenStringFilterTest.java    | 76 +++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/org.jacoco.core.test/src/org/jacoco/core/internal/analysis/filter/KotlinWhenStringFilterTest.java b/org.jacoco.core.test/src/org/jacoco/core/internal/analysis/filter/KotlinWhenStringFilterTest.java
index a61f3f8df9..f3a548c552 100644
--- a/org.jacoco.core.test/src/org/jacoco/core/internal/analysis/filter/KotlinWhenStringFilterTest.java
+++ b/org.jacoco.core.test/src/org/jacoco/core/internal/analysis/filter/KotlinWhenStringFilterTest.java
@@ -106,6 +106,82 @@ public void should_filter() {
 		assertIgnored(new Range(expectedFromInclusive, expectedToInclusive));
 	}
 
+	/**
+	 * <pre>
+	 * fun example(p: String) {
+	 *   when (p) {
+	 *     "b" -> return
+	 *     "a" -> return
+	 *     "\u0000a" -> return
+	 *   }
+	 * }
+	 * </pre>
+	 */
+	@Test
+	public void should_filter_when_biggest_hashCode_first() {
+		final Set<AbstractInsnNode> expectedNewTargets = new HashSet<AbstractInsnNode>();
+
+		final MethodNode m = new MethodNode(InstrSupport.ASM_API_VERSION, 0,
+				"example", "(Ljava/lang/String;)V", null, null);
+
+		final Label h1 = new Label();
+		final Label sameHash = new Label();
+		final Label h2 = new Label();
+		final Label case1 = new Label();
+		final Label case2 = new Label();
+		final Label case3 = new Label();
+		final Label defaultCase = new Label();
+
+		m.visitVarInsn(Opcodes.ALOAD, 2);
+		m.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/String", "hashCode",
+				"()I", false);
+		m.visitTableSwitchInsn(97, 98, defaultCase, h1, h2);
+
+		m.visitLabel(h1);
+		final AbstractInsnNode expectedFromInclusive = m.instructions.getLast();
+		m.visitVarInsn(Opcodes.ALOAD, 2);
+		m.visitLdcInsn("a");
+		m.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/String", "equals",
+				"(Ljava/lang/Object;)Z", false);
+		m.visitJumpInsn(Opcodes.IFEQ, sameHash);
+		m.visitJumpInsn(Opcodes.GOTO, case2);
+
+		m.visitLabel(sameHash);
+		m.visitVarInsn(Opcodes.ALOAD, 2);
+		m.visitLdcInsn("\u0000a");
+		m.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/String", "equals",
+				"(Ljava/lang/Object;)Z", false);
+		m.visitJumpInsn(Opcodes.IFEQ, defaultCase);
+		m.visitJumpInsn(Opcodes.GOTO, case3);
+
+		m.visitLabel(h2);
+		m.visitVarInsn(Opcodes.ALOAD, 2);
+		m.visitLdcInsn("b");
+		m.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/String", "equals",
+				"(Ljava/lang/Object;)Z", false);
+		m.visitJumpInsn(Opcodes.IFEQ, defaultCase);
+		final AbstractInsnNode expectedToInclusive = m.instructions.getLast();
+
+		m.visitLabel(case1);
+		m.visitInsn(Opcodes.RETURN);
+		expectedNewTargets.add(m.instructions.getLast());
+		m.visitLabel(case2);
+		m.visitInsn(Opcodes.RETURN);
+		expectedNewTargets.add(m.instructions.getLast());
+		m.visitLabel(case3);
+		m.visitInsn(Opcodes.RETURN);
+		expectedNewTargets.add(m.instructions.getLast());
+		m.visitLabel(defaultCase);
+		m.visitInsn(Opcodes.RETURN);
+		expectedNewTargets.add(m.instructions.getLast());
+
+		filter.filter(m, context, output);
+
+		assertIgnored(new Range(expectedFromInclusive, expectedToInclusive));
+		assertReplacedBranches(expectedFromInclusive.getPrevious(),
+				expectedNewTargets);
+	}
+
 	@Test
 	public void should_not_filter_empty_lookup_switch() {
 		final MethodNode m = new MethodNode(InstrSupport.ASM_API_VERSION, 0,