text: from unittest import TestCase
  
  from number_of_islands import Solution
  
  
  class TestEmptyCases(TestCase):
      def test_zero_for_2_by_2(self):
          self.assertEqual(
              Solution().numIslands(
                  [
                      ["0", "0"],
                      ["0", "0"],
                  ]
              ),
              0
          )
  
  
  class TestFilledTwoByTwo(TestCase):
      def test_is_one(self):
          self.assertEqual(
              Solution().numIslands(
                  [
                      ["1", "1"],
                      ["1", "1"],
                  ]
              ),
              1,
          )
  
  
  class TestTwoIslandsInTwoByTwo(TestCase):
      def test_is_two(self):
          self.assertEqual(
              Solution().numIslands(
                  [
                      ["1", "0"],
                      ["0", "1"],
                  ]
              ),
              2,
          )
  
  
  class TestAllButOneFilledTwoByTwo(TestCase):
      def test_is_one(self):
          self.assertEqual(
              Solution().numIslands(
                  [
                      ["1", "0"],
                      ["1", "1"],
                  ]
              ),
              1,
          )
  
  
  