Moving Downstream

This last set of changes left me well positioned to implement the various aspects of the output. Commit [99cb54b] introduced an effective but somewhat awkward test to verify that System.out was used for normal output. I call it awkward because of the use of the copiedToOutput variable that needed checking in the override of retrieve(), shown in Listing 14-7. This amounted to a hand-rolled mock. If I left out the flag, I would have no guarantee that copyToOutput() was called and therefore that its assertion had been evaluated.

Listing 14-7: Effective but awkward test with hand-rolled mock to verify that System.out is used for output

Click here to view code image

public void testRetrieve_StandardOutput()
    throws IOException, URISyntaxException {
  final String expectedContent = "This should go to stdout";
  Target sut = new Target(EXAMPLE_URI, false) {
    boolean copiedToOutput = false;

    @Override
    public void retrieve()
        throws IOException, URISyntaxException {
      super.retrieve();
      assertThat(copiedToOutput, is(true));
    }

    @Override
    protected void retrieveResponse()
        throws IOException, URISyntaxException {
      setResponse(
        WebRetrieverTest.createMockResponse(expectedContent));
    }

    @Override
    protected void copyToOutput(
          InputStream content, OutputStream output)
        throws IOException {
      assertThat(System.out, is(output));
      copiedToOutput = true;
    }
  };

  sut.retrieve();
}

The following commit, [f89bf38], refactors the anonymous inner class to an explicit nested class and turns it into a spy rather than a mock. This yields a nicer-looking test as well as a reusable spy for the other output variations (Listing 14-8).

Listing 14-8: Cleaned up version of the test in Listing 14-7 showing a cleaner testing style and preparing for reuse in upcoming variations

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public void testRetrieve_StandardOutput()
    throws IOException, URISyntaxException {
  OutputSpyTarget sut =
    new OutputSpyTarget(EXAMPLE_URI, false);

  sut.retrieve();

  OutputStream outputStream = sut.getOutputStream();
  assertThat(outputStream, is(notNullValue()));
  assertThat(System.out, is(outputStream));
}

class OutputSpyTarget extends Target {
  OutputStream outputStream = null;

  public OutputSpyTarget(String URI, boolean writeToFile)
      throws URISyntaxException {
    super(URI, writeToFile);
  }

  @Override
  protected void retrieveResponse()
      throws IOException, URISyntaxException {
    setResponse(WebRetrieverTest.createMockResponse(""));
  }

  @Override
  protected void copyToOutput(
        InputStream content, OutputStream output)
      throws IOException {
    outputStream = output;
  }

  public OutputStream getOutputStream() {
    return outputStream;
  }
}

The remainder of the commits use the OutputSpyTarget to verify that it writes to a file and that it fails when no file path is given.