// Crude test program for an immutable Stack<E> ADT.

public class TestStack {

    // Runs the tests.
               
    public static void main(String args[]) {
        TestStack test = new TestStack();
        test.creation();
        test.accessors();
        test.summarize();
    }

    private void summarize () {
        System.out.println();
        System.out.println (totalErrors + " errors found in " +
                            totalTests + " tests.");
    }

    public TestStack () { }

    private Stack<Integer> s0;
    private Stack<Integer> s1;
    private Stack<Integer> s2;
    private Stack<Integer> s3;
    private Stack<Integer> s4;
    private Stack<Integer> s5;
    private Stack<Integer> s6;

    // Creates some Stack<Integer> objects and stores them in this object.

    private void creation () {
        try {
            s0 = Stacks.empty();
            s1 = s0.push (1);
            s2 = s1.push (2);
            s3 = s2.push (3);
            s4 = s0.push (4);
            s5 = s2.push (5);
            s6 = s5.push (6);
        }
        catch (Exception e) {
            assertTrue ("creation", false);
        }
    }

    private void accessors () {
        try {
            assertTrue ("isEmpty:s0", s0.isEmpty());
            assertFalse ("isEmpty:s1", s1.isEmpty());

            assertTrue ("top:s1", s1.top() == 1);
            assertTrue ("pop:s1", s1.pop().isEmpty());

            assertTrue ("size:s0", s0.size() == 0);
            assertTrue ("size:s1", s1.size() == 1);
            assertTrue ("size:s4", s4.size() == 1);
            assertTrue ("size:s6", s6.size() == 4);
            assertTrue ("size:s5", s6.pop().size() == 3);
            assertTrue ("size:s6", s6.size() == 4);

	    assertTrue ("top:null", s6.push(null).top() == null);
	    assertTrue ("pop:null", s6.push(null).pop().equals(s6));

	    // This isn't really a test, just an example.

	    Stack<Integer> s = s6;
	    while (! s.isEmpty()) {
		System.out.println (s.top());
		s = s.pop();
	    }
            System.out.println();
            s = s6;
	    while (! s.isEmpty()) {
		System.out.println (s.top());
		s = s.pop();
	    }
        }
        catch (Exception e) {
            assertTrue ("accessors", false);
        }
    }

    private int totalTests = 0;       // tests run so far
    private int totalErrors = 0;      // errors so far

    // For anonymous tests.  Deprecated.

    private void assertTrue (boolean result) {
      assertTrue ("anonymous", result);
    }

    // Prints failure report if the result is not true.

    private void assertTrue (String name, boolean result) {
        if (! result) {
            System.out.println ();
            System.out.println ("***** Test failed ***** "
                                + name + ": " +totalTests);
            totalErrors = totalErrors + 1;
        }
        totalTests = totalTests + 1;
    }

    // For anonymous tests.  Deprecated.

    private void assertFalse (boolean result) {
        assertTrue (! result);
    }

    // Prints failure report if the result is not false.

    private void assertFalse (String name, boolean result) {
        assertTrue (name, ! result);
    }

}