core/src/main/java/io/grpc/internal/FailingClientStream.java

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package io.grpc.internal;

import com.google.common.base.Preconditions;

import io.grpc.Metadata;
import io.grpc.Status;

/**
 * An implementation of {@link ClientStream} that fails (by calling {@link
 * ClientStreamListener#closed}) when started, and silently does nothing for the other operations.
 */
class FailingClientStream extends NoopClientStream {
  private boolean started;
  private final Status error;

  /**
   * Creates a {@code FailingClientStream} that would fail with the given error.
   */
  public FailingClientStream(Status error) {
    Preconditions.checkArgument(!error.isOk(), "error must not be OK");
    this.error = error;
  }

  @Override
  public void start(ClientStreamListener listener) {
    Preconditions.checkState(!started, "already started");
    started = true;
    listener.closed(error, new Metadata());
  }

  Status getError() {
    return error;
  }
}