CIT plugin change_one_value fix

When the chosen value can't be changed, bacause of some constrain. The function randomly choose diferent valueWhen the chosen value couldn't be changed, because of some constraints. The function randomly chose different value, which is not expected behavior. Now when this event occurs, the function raises ValueError exception and it's handled.
Signed-off-by: NJan Richter <jarichte@redhat.com>

optional_plugins/varianter_cit/avocado_varianter_cit/Cit.py

@@ -101,9 +101,10 @@ class Cit:
         while self.combination_matrix.total_uncovered != 0:
             LOG.debug(self.__throbber.render(), extra={"skip_newline": True})
             solution, row_index, _ = self.use_random_algorithm(matrix)
-            self.combination_matrix.uncover_solution_row(matrix[row_index])
-            self.combination_matrix.cover_solution_row(solution)
-            matrix[row_index] = solution
+            if len(solution) != 0:
+                self.combination_matrix.uncover_solution_row(matrix[row_index])
+                self.combination_matrix.cover_solution_row(solution)
+                matrix[row_index] = solution
             if counter == 0:
                 return matrix, False
             counter -= 1
@@ -197,8 +198,6 @@ class Cit:
                 self.combination_matrix.cover_combination(matrix[row_index], parameters)
                 if best_uncover == 0:
                     break
-        if len(best_solution) == 0:
-            return self.change_one_column(matrix)
         return best_solution, best_row_index, parameters
 
     def get_missing_combination_random(self):
@@ -229,7 +228,10 @@ class Cit:
         best_solution = []
         best_row_index = 0
         for row_index in range(len(matrix)):
-            solution, row_index, parameters = self.change_one_value(matrix, row_index, column_index)
+            try:
+                solution, row_index, parameters = self.change_one_value(matrix, row_index, column_index)
+            except ValueError:
+                continue
             self.combination_matrix.uncover_combination(matrix[row_index], parameters)
             self.combination_matrix.cover_combination(solution, parameters)
             if self.combination_matrix.total_uncovered < best_uncover:
@@ -251,10 +253,13 @@ class Cit:
         :param column_index: column inside matrix. If it's None it is chosen randomly
         :return: solution, index of solution inside matrix and parameters which has been changed
         """
+        is_cell_chosen = True
         if row_index is None:
+            is_cell_chosen = False
             row_index = random.randint(0, len(matrix) - 1)
         row = [x for x in matrix[row_index]]
         if column_index is None:
+            is_cell_chosen = False
             column_index = random.randint(0, len(row) - 1)
         possible_numbers = list(range(0, row[column_index])) + list(
             range(row[column_index] + 1, self.data[column_index]))
@@ -262,6 +267,8 @@ class Cit:
         while not self.combination_matrix.is_valid_combination(row, [column_index]):
             possible_numbers.remove(row[column_index])
             if len(possible_numbers) == 0:
+                if is_cell_chosen:
+                    raise ValueError("Selected cell can't be changed")
                 column_index = random.randint(0, len(row) - 1)
                 row_index = random.randint(0, len(matrix) - 1)
                 row = [x for x in matrix[row_index]]

optional_plugins/varianter_cit/tests/test_cit.py

@@ -71,13 +71,23 @@ class CitTests(unittest.TestCase):
         final_matrix = self.cit.final_matrix_init()
         expected_row_index = 2
         expected_column_index = 0
-        row, row_index, column_index = self.cit.change_one_value(final_matrix, row_index=expected_row_index,
-                                                                 column_index=expected_column_index)
-        self.assertEqual(expected_column_index, column_index[0], "Column index is wrong")
-        self.assertEqual(expected_row_index, row_index, "Row index is wrong")
-        self.assertNotEqual(final_matrix[row_index][column_index[0]], row[column_index[0]], "Value did not change")
-        row[column_index[0]] = final_matrix[row_index][column_index[0]]
-        self.assertEqual(final_matrix[row_index], row, "Different value was changed")
+        function_state = True
+        row, row_index, column_index = (None, None, None)
+        try:
+            row, row_index, column_index = self.cit.change_one_value(final_matrix, row_index=expected_row_index,
+                                                                     column_index=expected_column_index)
+        except ValueError:
+            function_state = False
+        if function_state:
+            self.assertEqual(expected_column_index, column_index[0], "Column index is wrong")
+            self.assertEqual(expected_row_index, row_index, "Row index is wrong")
+            self.assertNotEqual(final_matrix[row_index][column_index[0]], row[column_index[0]], "Value did not change")
+            row[column_index[0]] = final_matrix[row_index][column_index[0]]
+            self.assertEqual(final_matrix[row_index], row, "Different value was changed")
+        else:
+            self.assertIsNone(row)
+            self.assertIsNone(row_index)
+            self.assertIsNone(column_index)
 
     def test_change_one_column(self):
         final_matrix = self.cit.final_matrix_init()