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[Draft] Add stderr to process result output #751

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[Draft] Add stderr to process result output #751

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12 changes: 11 additions & 1 deletion docker-compose-rule-core/src/main/java/com/palantir/docker/compose/execution/Command.java
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Original file line number Diff line number Diff line change
Expand Up @@ -80,10 +80,20 @@ private ProcessResult run(String... commands) throws IOException, InterruptedExc
}

private String processOutputFrom(Process process) {
return asReader(process.getInputStream())
String stdout = asReader(process.getInputStream())
.lines()
.peek(logConsumer)
.collect(Collectors.joining(System.lineSeparator()));

String stderr = asReader(process.getErrorStream())
.lines()
.peek(logConsumer)
.collect(Collectors.joining(System.lineSeparator()));

return String.format(
"STDERR: %s\n\n------\n\nSTDOUT: %s\n",
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@felixdesouza felixdesouza Feb 10, 2026

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can we just use multi line strings here?

stderr.isEmpty() ? "<empty>" : stderr,
stdout.isEmpty() ? "<empty>" : stdout);
}

private static String waitForResultFrom(Future<String> outputProcessing) {
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41 changes: 39 additions & 2 deletions ...-compose-rule-core/src/test/java/com/palantir/docker/compose/execution/CommandShould.java
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,7 @@ public void before() throws IOException {
dockerComposeCommand = new Command(dockerComposeExecutable, logConsumer);

givenTheUnderlyingProcessHasOutput("");
givenTheUnderlyingProcessHasError("");
givenTheUnderlyingProcessTerminatesWithAnExitCodeOf(0);
}

Expand All @@ -72,7 +73,7 @@ public void return_output_when_exit_code_of_the_executed_process_is_non_0()
givenTheUnderlyingProcessHasOutput(expectedOutput);
String commandOutput = dockerComposeCommand.execute(errorHandler, "rm", "-f");

assertThat(commandOutput).isEqualTo(expectedOutput);
assertThat(commandOutput).isEqualTo("STDERR: <empty>\n\n------\n\nSTDOUT: " + expectedOutput + "\n");
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@felixdesouza felixdesouza Feb 10, 2026

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with multi line strings you should be able to do something like:

assertThat(commandOutput).isEqualTo(
  """
  STDERR: <empty>
  
  ------
  
  STDOUT:  %s
  """, expectedOutput);

assertj has some nice utility methods to do string formatting inside

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@felixdesouza felixdesouza Feb 10, 2026

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It also gives me a way to see what the actual error message would look like.

So much so, I would actually just put the content for each stream on a new line

e.g.

STDERR:
<empty>

------
STDOUT:
%s

}

@Test
Expand All @@ -81,7 +82,29 @@ public void return_output_when_exit_code_of_the_executed_process_is_0() throws I
givenTheUnderlyingProcessHasOutput(expectedOutput);
String commandOutput = dockerComposeCommand.execute(errorHandler, "rm", "-f");

assertThat(commandOutput).isEqualTo(expectedOutput);
assertThat(commandOutput).isEqualTo("STDERR: <empty>\n\n------\n\nSTDOUT: " + expectedOutput + "\n");
}

@Test
public void return_output_when_only_stderr_is_present() throws IOException, InterruptedException {
String expectedStderr = "error output";
givenTheUnderlyingProcessHasError(expectedStderr);
String commandOutput = dockerComposeCommand.execute(errorHandler, "rm", "-f");

assertThat(commandOutput)
.isEqualTo("STDERR: " + expectedStderr + "\n\n------\n\nSTDOUT: <empty>\n");
}

@Test
public void return_output_containing_both_stderr_and_stdout() throws IOException, InterruptedException {
String expectedStdout = "standard output";
String expectedStderr = "error output";
givenTheUnderlyingProcessHasOutput(expectedStdout);
givenTheUnderlyingProcessHasError(expectedStderr);
String commandOutput = dockerComposeCommand.execute(errorHandler, "rm", "-f");

assertThat(commandOutput)
.isEqualTo("STDERR: " + expectedStderr + "\n\n------\n\nSTDOUT: " + expectedStdout + "\n");
}

@Test
Expand All @@ -94,6 +117,16 @@ public void give_the_output_to_the_specified_consumer_as_it_is_available()
assertThat(consumedLogLines).containsExactly("line 1", "line 2");
}

@Test
public void give_both_stdout_and_stderr_to_the_specified_consumer() throws IOException, InterruptedException {
givenTheUnderlyingProcessHasOutput("stdout line");
givenTheUnderlyingProcessHasError("stderr line");

dockerComposeCommand.execute(errorHandler, "rm", "-f");

assertThat(consumedLogLines).containsExactly("stdout line", "stderr line");
}

// flaky test: https://circleci.com/gh/palantir/docker-compose-rule/378, 370, 367, 366
@Ignore
@Test
Expand All @@ -110,6 +143,10 @@ private void givenTheUnderlyingProcessHasOutput(String output) {
when(executedProcess.getInputStream()).thenReturn(toInputStream(output));
}

private void givenTheUnderlyingProcessHasError(String error) {
when(executedProcess.getErrorStream()).thenReturn(toInputStream(error));
}

private void givenTheUnderlyingProcessTerminatesWithAnExitCodeOf(int exitCode) {
when(executedProcess.exitValue()).thenReturn(exitCode);
}
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