function assertExitCode(exitingProcess, expectedExitCode) {
	return awaitExit(exitingProcess).then(exitCode => {
		assert.strictEqual(
			exitCode,
			expectedExitCode,
			`Expected an exit code of ${expectedExitCode} but got ${exitCode}.`,
		);
	});
}
Asserts that the exit code of a given child process will equal the given value.
@param {ChildProcess} exitingProcess The child process
@param {number} expectedExitCode The expected exit code of the child process
@returns {Promise<void>} A Promise that fulfills if the exit code ends up matching, and rejects otherwise.