/*

 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package toolbox;

import java.io.PrintStream;

import java.lang.annotation.Annotation;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.util.function.Function;

/**

 * Utility class to manage and execute sub-tests within a test.

 *

 * This class does the following:

 * <ul>

 * <li>  invokes those test methods annotated with @Test

 * <li>  keeps track of successful and failed tests

 * <li>  throws an Exception if any test fails.

 * <li>  provides a test summary at the end of the run.

 * </ul>

 * Tests must extend this class, annotate the test methods

 * with @Test and call one of the runTests method.

 */

public abstract class TestRunner {

   /** Marker annotation for test cases. */

    @Retention(RetentionPolicy.RUNTIME)

    public @interface Test { }

    int testCount = 0;

    int errorCount = 0;

    public String testName = null;

    protected PrintStream out;

    /**

     * Constructs the Object.

     * @param out the PrintStream to print output to.

     */

    public TestRunner(PrintStream out) {

        this.out = out;

    }

    /**

     * Invoke all methods annotated with @Test.

     * @throws java.lang.Exception if any errors occur

     */

    protected void runTests() throws Exception {

        runTests(f -> new Object[0]);

    }

    /**

     * Invoke all methods annotated with @Test.

     * @param f a lambda expression to specify arguments for the test method

     * @throws java.lang.Exception if any errors occur

     */

    protected void runTests(Function<Method, Object[]> f) throws Exception {

        for (Method m : getClass().getDeclaredMethods()) {

            Annotation a = m.getAnnotation(Test.class);

            if (a != null) {

                testName = m.getName();

                try {

                    testCount++;

                    out.println("test: " + testName);

                    m.invoke(this, f.apply(m));

                } catch (InvocationTargetException e) {

                    errorCount++;

                    Throwable cause = e.getCause();

                    cause.printStackTrace(out);

                }

                out.println();

            }

        }

        if (testCount == 0) {

            throw new Error("no tests found");

        }

        StringBuilder summary = new StringBuilder();

        if (testCount != 1) {

            summary.append(testCount).append(" tests");

        }

        if (errorCount > 0) {

            if (summary.length() > 0) {

                summary.append(", ");

            }

            summary.append(errorCount).append(" errors");

        }

        out.println(summary);

        if (errorCount > 0) {

            throw new Exception(errorCount + " errors found");

        }

    }

    protected void error(String message) {

        out.println("Error: " + message);

        errorCount++;

    }

}