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jevanlingen merged 3 commits into from
Aug 13, 2025
Merged

Improve Java 17 and Java 21 switch expression tests #822

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Improve java 17 switch expression tests
jevanlingen Aug 13, 2025
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2 changes: 1 addition & 1 deletion src/main/resources/META-INF/rewrite/java-version-21.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -136,7 +136,7 @@ recipeList:
type: specs.openrewrite.org/v1beta/recipe
name: org.openrewrite.java.migrate.SwitchPatternMatching
displayName: Adopt switch pattern matching (JEP 441)
description: ->-
description: >-
[JEP 441](https://openjdk.org/jeps/441) describes how some switch statements can be improved with pattern matching.
This recipe applies some of those improvements where applicable.
tags:
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332 changes: 332 additions & 0 deletions ...rg/openrewrite/java/migrate/lang/EnhancedSwitchCaseAssignmentsToSwitchExpressionTest.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,332 @@
/*
* Copyright 2025 the original author or authors.
* <p>
* Licensed under the Moderne Source Available License (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* <p>
* https://docs.moderne.io/licensing/moderne-source-available-license
* <p>
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.openrewrite.java.migrate.lang;

import org.junit.jupiter.api.Test;
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import org.openrewrite.DocumentExample;
import org.openrewrite.test.RecipeSpec;
import org.openrewrite.test.RewriteTest;

import static org.openrewrite.java.Assertions.java;
import static org.openrewrite.java.Assertions.version;

@SuppressWarnings({"EnhancedSwitchMigration", "RedundantLabeledSwitchRuleCodeBlock", "UnusedAssignment"})
class EnhancedSwitchCaseAssignmentsToSwitchExpressionTest implements RewriteTest {
@Override
public void defaults(RecipeSpec spec) {
spec
.recipe(new SwitchCaseAssignmentsToSwitchExpression())
.allSources(source -> version(source, 21));
}

@DocumentExample
@Test
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void convertSimpleArrowCasesAssignment() {
rewriteRun(
//language=java
java(
"""
class Test {
void doFormat(Object obj) {
String formatted = "initialValue";
switch (obj) {
case Integer i -> formatted = String.format("int %d", i);
case Long l -> formatted = String.format("long %d", l);
default -> formatted = "unknown";
}
}
}
""",
"""
class Test {
void doFormat(Object obj) {
String formatted = switch (obj) {
case Integer i -> String.format("int %d", i);
case Long l -> String.format("long %d", l);
default -> "unknown";
};
}
}
"""
)
);
}

@Test
void convertSimpleColonCasesAssignment() {
rewriteRun(
//language=java
java(
"""
class Test {
void doFormat(Object obj) {
String formatted = "initialValue";
switch (obj) {
case Integer i: formatted = String.format("int %d", i); break;
case Long l: formatted = String.format("long %d", l); break;
default: formatted = "unknown"; break;
}
}
}
""",
"""
class Test {
void doFormat(Object obj) {
String formatted = switch (obj) {
case Integer i -> String.format("int %d", i);
case Long l -> String.format("long %d", l);
default -> "unknown";
};
}
}
"""
)
);
}

@Test
void notConvertSimpleColonCasesAssignmentWithExtraCodeInBlock() {
// Only one statement [+break;] per case is currently supported
rewriteRun(
//language=java
java(
"""
class Test {
void doFormat(Object obj) {
String formatted = "initialValue";
switch (obj) {
case Integer i: formatted = String.format("int %d", i); break;
case Long l: System.out.println("long"); formatted = String.format("long %d", l); break;
default: formatted = "unknown"; break;
}
}
}
"""
)
);
}

@Test
void convertColonCasesSimpleAssignmentInBlockToSingleYield() {
rewriteRun(
//language=java
java(
"""
class Test {
void doFormat(Object obj) {
String formatted = "initialValue";
switch (obj) {
case Integer i: formatted = String.format("int %d", i); break;
case Long l: {
formatted = String.format("long %d", l);
break;
}
default: formatted = "unknown"; break;
}
}
}
""",
"""
class Test {
void doFormat(Object obj) {
String formatted = switch (obj) {
case Integer i -> String.format("int %d", i);
case Long l -> String.format("long %d", l);
default -> "unknown";
};
}
}
"""
)
);
}

@Test
void convertColonCasesSimpleAssignmentInBlockToSingleYieldWithoutFinalCaseBreak() {
rewriteRun(
//language=java
java(
"""
class Test {
void doFormat(Object obj) {
String formatted = "initialValue";
switch (obj) {
case Integer i: formatted = String.format("int %d", i); break;
case Long l: {
formatted = String.format("long %d", l);
break;
}
default: formatted = "unknown";
}
}
}
""",
"""
class Test {
void doFormat(Object obj) {
String formatted = switch (obj) {
case Integer i -> String.format("int %d", i);
case Long l -> String.format("long %d", l);
default -> "unknown";
};
}
}
"""
)
);
}

@Test
void convertArrowCasesSimpleAssignmentInBlockToSingleValue() {
rewriteRun(
//language=java
java(
"""
class Test {
void doFormat(Object obj) {
String formatted = "initialValue";
switch (obj) {
case Integer i -> formatted = String.format("int %d", i);
case Long l -> {
formatted = String.format("long %d", l);
}
default -> formatted = "unknown";
}
}
}
""",
"""
class Test {
void doFormat(Object obj) {
String formatted = switch (obj) {
case Integer i -> String.format("int %d", i);
case Long l -> String.format("long %d", l);
default -> "unknown";
};
}
}
"""
)
);
}

@Test
void notConvertCasesWithMissingAssignment() {
rewriteRun(
//language=java
java(
"""
class Test {
void doFormat(Object obj) {
String formatted = "initialValue";
switch (obj) {
case String s: formatted = String.format("String %s", s); break;
case Integer i: System.out.println("Integer!"); break;
default: formatted = "unknown"; break;
}
}
}
"""
)
);
}

@Test
void notConvertCasesWithAssignmentToDifferentVariables() {
rewriteRun(
//language=java
java(
"""
class Test {
void doFormat(Object obj) {
String formatted = "initialValue";
String formatted2 = "anotherInitialValue";
switch (obj) {
case String s: formatted = String.format("String %s", s); break;
case Integer i: formatted2 = String.format("Integer %d", i); break;
default: formatted = "unknown"; break;
}
}
}
"""
)
);
}

@Test
void defaultAsSecondLabelColonCase() {
rewriteRun(
//language=java
java(
"""
class A {
void doFormat(String str) {
String formatted = "initialValue";
switch (str) {
case "foo": formatted = "Foo"; break;
case "bar": formatted = "Bar"; break;
case null, default: formatted = "unknown";
}
}
}
""",
"""
class A {
void doFormat(String str) {
String formatted = switch (str) {
case "foo" -> "Foo";
case "bar" -> "Bar";
case null, default -> "unknown";
};
}
}
"""
)
);
}

@Test
void defaultAsSecondLabelArrowCase() {
rewriteRun(
//language=java
java(
"""
class B {
void doFormat(String str) {
String formatted = "initialValue";
switch (str) {
case "foo" -> formatted = "Foo";
case "bar" -> formatted = "Bar";
case null, default -> formatted = "Other";
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}
}
}
""",
"""
class B {
void doFormat(String str) {
String formatted = switch (str) {
case "foo" -> "Foo";
case "bar" -> "Bar";
case null, default -> "Other";
};
}
}
"""
)
);
}
}
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