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Don't assert exact exception type when StackOverflowError is thrown #2815

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Merged
eamonnmcmanus merged 2 commits into from
Feb 23, 2025
Merged

Don't assert exact exception type when StackOverflowError is thrown #2815

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9a69c64
Don't assert exact exception type when StackOverflowError is thrown
Marcono1234 Feb 22, 2025
88e389c
Check for StackOverflowError as root cause
Marcono1234 Feb 22, 2025
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16 changes: 13 additions & 3 deletions gson/src/test/java/com/google/gson/functional/CircularReferenceTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertThrows;

import com.google.common.base.Throwables;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
Expand All @@ -30,6 +31,7 @@
import java.util.Collection;
import org.junit.Before;
import org.junit.Test;
import org.junit.function.ThrowingRunnable;

/**
* Functional tests related to circular reference detection and error reporting.
Expand All @@ -52,7 +54,7 @@ public void testCircularSerialization() {
a.children.add(b);
b.children.add(a);
// Circular types should not get printed
assertThrows(StackOverflowError.class, () -> gson.toJson(a));
assertThrowsStackOverflow(() -> gson.toJson(a));
}

@Test
Expand All @@ -70,7 +72,7 @@ public void testSelfReferenceArrayFieldSerialization() {
objA.children = new ClassWithSelfReferenceArray[] {objA};

// Circular reference to self can not be serialized
assertThrows(StackOverflowError.class, () -> gson.toJson(objA));
assertThrowsStackOverflow(() -> gson.toJson(objA));
}

@Test
Expand All @@ -96,7 +98,15 @@ public JsonElement serialize(
.create();

// Circular reference to self can not be serialized
assertThrows(StackOverflowError.class, () -> gson.toJson(obj));
assertThrowsStackOverflow(() -> gson.toJson(obj));
}

/** Asserts that a {@link StackOverflowError} is thrown. */
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@eamonnmcmanus eamonnmcmanus Feb 22, 2025

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But it doesn't assert that, does it? 🙂 I think we can probably assume that StackOverflowError is at least in the cause chain, and probably that it is the root cause. So then this?

Throwable t = assertThrows(Throwable.class, runnable);
assertThat(Throwables.getRootCause(t)).isInstanceOf(StackOverflowError.class);

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@Marcono1234 Marcono1234 Feb 22, 2025

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But it doesn't assert that, does it?

Yes you are right. My intention was to indicate that this methods is intended for cases where a StackOverflowError is expected, but then the implementation admits that it cannot reliably detect that.

I think we can probably assume that StackOverflowError is at least in the cause chain

Yes that could be an option. Let's just hope that there is no JDK code which sets it only as 'suppressed exception', or which entirely discards the cause.

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@eamonnmcmanus eamonnmcmanus Feb 23, 2025

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Right. If that ever happens, we can adjust accordingly.

private static void assertThrowsStackOverflow(ThrowingRunnable runnable) {
// Obtain the root cause because the StackOverflowError might occur in JDK code, and that might
// wrap it in another exception class, for example InternalError
Throwable t = assertThrows(Throwable.class, runnable);
assertThat(Throwables.getRootCause(t)).isInstanceOf(StackOverflowError.class);
}

@Test
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