/*output_names=*/nullptr,
                             /*opts=*/nullptr, description, s.get());
  ASSERT_EQ(TF_OK, TF_GetCode(s.get())) << TF_Message(s.get());
  ASSERT_NE(*func, nullptr);
}

class CApiExperimentalFunctionTest : public ::testing::Test {
 protected:
  CApiExperimentalFunctionTest()
      : s_(TF_NewStatus()), func_graph_(TF_NewGraph()), func_(nullptr) {}

    // is cancelled.
    future1.cancel(false);

    // Give the second task a chance to (incorrectly) start up while the first task is running.
    // (This is the assertion that fails.)
    assertThat(future2.isDone()).isFalse();

    // Stop the first task. The second task should then run.
    blockingCallable.stop();
    executor.shutdown();

  // Custom device: inputs in different custom devices fails.
  matmul.reset(MatMulOp(context.get(), hcustom0.get(), hcustom1.get()));
  num_retvals = 1;
  TFE_Execute(matmul.get(), &retval, &num_retvals, status.get());
  ASSERT_NE(TF_OK, TF_GetCode(status.get()));
  ASSERT_TRUE(absl::StrContains(TF_Message(status.get()), custom0));
  ASSERT_TRUE(absl::StrContains(TF_Message(status.get()), custom1));

}
```

## 🏗️ Architecture & Design Patterns

### Core Design Principles
CoreLib follows a **utility-class pattern** where most functionality is exposed through static methods:

- **Assertion-based validation** - All methods validate inputs using `AssertionUtil.assertArgumentNotNull()` and `AssertionUtil.assertArgumentNotEmpty()`

            Set<Coordinates> gavs = InferenceStrategy.computeAllArtifactCoordinates(context, largePomMap);
            long endTime = System.currentTimeMillis();

            // Performance assertion - should complete within reasonable time
            long duration = endTime - startTime;
            assertTrue(duration < 5000, "Artifact computation should complete within 5 seconds for 100 POMs");

			continue
		}
		// Test passes as expected, but the output values are verified for correctness here.
		if actualErr == nil {
			// Asserting whether the md5 output is correct.
			if expectedMD5, ok := testCase.inputMeta["etag"]; ok && expectedMD5 != objInfo.ETag {
				t.Errorf("Test %d: %s: Calculated Md5 different from the actual one %s.", i, instanceType, objInfo.ETag)

    assertThat(e).hasMessageThat().contains("toString representation");
  }

  private static void assertErrorMessage(Throwable e, String message) {
    // TODO(kevinb): use a Truth assertion here
    if (!e.getMessage().contains(message)) {
      fail("expected <" + e.getMessage() + "> to contain <" + message + ">");
    }
  }

  /**

     * iterator's next element and pass it to the reference iterator through this method so it can
     * return the same element. This enables the assertion to pass and the reference iterator to
     * properly update its state.
     */
    void promoteToNext(E e) {
      if (nextElements.remove(e)) {
        nextElements.push(e);
      } else {

import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A series of tests that support asserting that collections cannot be modified, either through
 * direct or indirect means.
 *
 * @author Robert Konigsberg
 */
@GwtCompatible
@NullMarked
public class UnmodifiableCollectionTests {

import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A series of tests that support asserting that collections cannot be modified, either through
 * direct or indirect means.
 *
 * @author Robert Konigsberg
 */
@GwtCompatible
@NullMarked
public class UnmodifiableCollectionTests {