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Add self-tests for assert[Not]Equals() with arrays #4899

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Add self-tests for assert[Not]Equals() with arrays #4899

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3adea80
Add self-tests for `assert[Not]Equals()` with arrays
sormuras Sep 1, 2025
9917f9c
Use system property flag
sormuras Dec 17, 2025
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11 changes: 10 additions & 1 deletion junit-jupiter-api/src/main/java/org/junit/jupiter/api/AssertionUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
import java.util.function.Supplier;

import org.jspecify.annotations.Nullable;
import org.junit.platform.commons.JUnitException;
import org.junit.platform.commons.annotation.Contract;
import org.junit.platform.commons.util.UnrecoverableExceptions;

Expand All @@ -27,7 +28,6 @@
* @since 5.0
*/
class AssertionUtils {

private AssertionUtils() {
/* no-op */
}
Expand Down Expand Up @@ -129,6 +129,15 @@ static boolean objectsAreEqual(@Nullable Object obj1, @Nullable Object obj2) {
if (obj1 == null) {
return (obj2 == null);
}
if (obj2 == null) {
return false;
}
if (Boolean.getBoolean("junit.jupiter.disallow.arrays.in.equals.checks")) {
if (obj1.getClass().isArray() && obj2.getClass().isArray()) {
throw new JUnitException(
"Detected array arguments:" + " " + obj1.getClass() + " and " + obj2.getClass());
}
}
return obj1.equals(obj2);
}

Expand Down
20 changes: 20 additions & 0 deletions jupiter-tests/src/test/java/org/junit/jupiter/api/AssertEqualsAssertionsTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
import static org.junit.jupiter.api.Assertions.assertThrows;

import org.junit.jupiter.api.function.Executable;
import org.junit.platform.commons.JUnitException;
import org.opentest4j.AssertionFailedError;

/**
Expand Down Expand Up @@ -750,6 +751,25 @@ void chars() {

}

@Nested
class ArraysAsArguments {
@Test
void objects() {
Object object = new Object();
Object array1 = new Object[] { object };
Object array2 = new Object[] { object };
try {
System.setProperty("junit.jupiter.disallow.arrays.in.equals.checks", "true");
var exception = assertThrows(JUnitException.class, () -> assertEquals(array1, array2));
assertEquals("Detected array arguments: class [Ljava.lang.Object; and class [Ljava.lang.Object;",
exception.getMessage());
}
finally {
System.clearProperty("junit.jupiter.disallow.arrays.in.equals.checks");
}
}
}

// -------------------------------------------------------------------------

@SuppressWarnings("overrides")
Expand Down
31 changes: 31 additions & 0 deletions jupiter-tests/src/test/java/org/junit/jupiter/api/AssertNotEqualsAssertionsTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,9 +14,16 @@
import static org.junit.jupiter.api.AssertionTestUtils.assertMessageEquals;
import static org.junit.jupiter.api.AssertionTestUtils.assertMessageStartsWith;
import static org.junit.jupiter.api.AssertionTestUtils.expectAssertionFailedError;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
import static org.junit.jupiter.api.Assertions.assertSame;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.util.Arrays;

import org.junit.platform.commons.JUnitException;
import org.opentest4j.AssertionFailedError;

/**
Expand Down Expand Up @@ -624,6 +631,30 @@ void assertNotEqualsInvokesEqualsMethodForIdenticalObjects() {

}

@Nested
class AssertNotEqualsArrays {
@Test
void objects() {
Object object = new Object();
Object array1 = new Object[] { object };
Object array2 = new Object[] { object };
assertThrows(AssertionFailedError.class, () -> assertSame(array1, array2));
assertThrows(AssertionFailedError.class, () -> assertEquals(array1, array2));
assertNotEquals(array1, array2); // succeeds
assertTrue(Arrays.deepEquals((Object[]) array1, (Object[]) array2));
assertArrayEquals((Object[]) array1, (Object[]) array2);
try {
System.setProperty("junit.jupiter.disallow.arrays.in.equals.checks", "true");
var exception = assertThrows(JUnitException.class, () -> assertNotEquals(array1, array2));
assertEquals("Detected array arguments: class [Ljava.lang.Object; and class [Ljava.lang.Object;",
exception.getMessage());
}
finally {
System.clearProperty("junit.jupiter.disallow.arrays.in.equals.checks");
}
}
}

// -------------------------------------------------------------------------

@Nested
Expand Down