"""unit tests for Stack
"""
import unittest
from stack import Stack

class StackEmptyTestCase(unittest.TestCase):
    """Test behaviour of an empty Stack."""
    def setUp(self):
        """Set up an empty stack."""
        self.stack = Stack()
    def tearDown(self):
        """Clean up."""
        self.stack = None
    def testIsEmpty(self):
        """Test is_empty() on empty Stack."""
        self.assertTrue(self.stack.is_empty(),
                        "is_empty returned False on empty Stack")
    def testadd(self):
        """Test add to empty Stack."""

        self.stack.add("foo")
        self.assertEqual(self.stack.remove(), "foo")


class StackAllTestCase(unittest.TestCase):
    """Comprehensive tests of (non-empty) Stack."""

    def setUp(self):
        """Set up an empty stack."""
        self.stack = Stack()

    def tearDown(self):
        """Clean up."""
        self.stack = None

    def testAll(self):
        """Test adding and removeping multiple elements."""

        for item in range(20):
            self.stack.add(item)
            self.assertTrue(not self.stack.is_empty(),
                            "is_empty() returned True on non-empty Stack!")

        expect = 19
        while not self.stack.is_empty():
            assert self.stack.remove() == expect, \
                ('Something wrong on top of the Stack! Expected ' +
                 str(expect) + '.')
            expect -= 1


if __name__ == '__main__':
    unittest.main(exit=False)