Class OutputCapture

lab03/tests/helpers/CaptureSystemOutput.java:108–192

OutputCapture captures output to System.out and System.err. To obtain an instance of OutputCapture, declare a parameter of type OutputCapture in a JUnit Jupiter @Test, @BeforeEach, or @AfterEach method. To obtain all output to {

     * @author Sam Brannen
     */
    static class OutputCapture {

//        private final List<Matcher<? super String>> matchers = new ArrayList<>();

        private CaptureOutputStream captureOut;

        private CaptureOutputStream captureErr;

        private ByteArrayOutputStream copy;

        void captureOutput() {
            this.copy = new ByteArrayOutputStream();
            this.captureOut = new CaptureOutputStream(System.out, this.copy);
            this.captureErr = new CaptureOutputStream(System.err, this.copy);
            System.setOut(new PrintStream(this.captureOut));
            System.setErr(new PrintStream(this.captureErr));
        }

        void releaseOutput() {
            System.setOut(this.captureOut.getOriginal());
            System.setErr(this.captureErr.getOriginal());
            this.copy = null;
        }

        private void flush() {
            try {
                this.captureOut.flush();
                this.captureErr.flush();
            } catch (IOException ex) {
                // ignore
            }
        }

        /**
         * Return all captured output to {@code System.out} and {@code System.err}
         * as a single string.
         */
        @Override
        public String toString() {
            flush();
            return this.copy.toString();
        }

        private static class CaptureOutputStream extends OutputStream {

            private final PrintStream original;

            private final OutputStream copy;

            CaptureOutputStream(PrintStream original, OutputStream copy) {
                this.original = original;
                this.copy = copy;
            }

            PrintStream getOriginal() {
                return this.original;
            }