import com.google.common.collect.ImmutableSet;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;

/** @author Colin Decker */
public class TestOutputStream extends FilterOutputStream {

  private final ImmutableSet<TestOption> options;
  private boolean closed;

import com.google.errorprone.annotations.Immutable;
import java.io.Serializable;
import java.util.zip.Checksum;

/**
 * {@link HashFunction} adapter for {@link Checksum} instances.
 *
 * @author Colin Decker
 */
@Immutable
@ElementTypesAreNonnullByDefault
final class ChecksumHashFunction extends AbstractHashFunction implements Serializable {
  private final ImmutableSupplier<? extends Checksum> checksumSupplier;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Random;

/**
 * A byte source for testing that has configurable behavior.
 *
 * @author Colin Decker
 */
public final class TestByteSource extends ByteSource implements TestStreamSupplier {

  private final byte[] bytes;
  private final ImmutableSet<TestOption> options;

  private boolean inputStreamOpened;

import java.io.FilterWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;

/**
 * A char sink for testing that has configurable behavior.
 *
 * @author Colin Decker
 */
public class TestCharSink extends CharSink implements TestStreamSupplier {

  private final TestByteSink byteSink;

  public TestCharSink(TestOption... options) {

import static com.google.common.base.Preconditions.checkNotNull;

import java.io.ByteArrayInputStream;
import java.io.FilterReader;
import java.io.IOException;
import java.io.InputStreamReader;

/** @author Colin Decker */
public class TestReader extends FilterReader {

  private final TestInputStream in;

  public TestReader(TestOption... options) throws IOException {

import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;

/**
 * Tests for {@link AbstractListeningExecutorService}.
 *
 * @author Colin Decker
 */
public class AbstractListeningExecutorServiceTest extends TestCase {

  public void testSubmit() throws Exception {
    /*
     * Mostly just tests that TrustedListenableFutureTask are created and run; tests for

 * Interface for a supplier of streams that can report whether a stream was opened and whether that
 * stream was closed. Intended for use in a test where only a single stream should be opened and
 * possibly closed.
 *
 * @author Colin Decker
 */
public interface TestStreamSupplier {

  /** Returns whether or not a new stream was opened. */
  boolean wasStreamOpened();

  /** Returns whether or not an open stream was closed. */

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.Multimap;

/**
 * Helper methods/assertions for use with {@code com.google.common.collect} types.
 *
 * @author Colin Decker
 */
@GwtCompatible
final class GoogleHelpers {

  private GoogleHelpers() {}

  static void assertEmpty(Multimap<?, ?> multimap) {
    if (!multimap.isEmpty()) {

## Use the instance as a dependency

Then, we could use this `checker` in a `Depends(checker)`, instead of `Depends(FixedContentQueryChecker)`, because the dependency is the instance, `checker`, not the class itself.

And when solving the dependency, **FastAPI** will call this `checker` like:

```Python
checker(q="somequery")
```

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Random;

/**
 * A byte source for testing that has configurable behavior.
 *
 * @author Colin Decker
 */
public final class TestByteSource extends ByteSource implements TestStreamSupplier {

  private final byte[] bytes;
  private final ImmutableSet<TestOption> options;

  private boolean inputStreamOpened;