Handle case of deleted files (#533)

* Handle case of deleted file

* Updating tests:

- Adding test with pycodestyle driver

- Adding test with pylint driver

Author: CliveCorbishleyTAL

diff_cover/violationsreporters/base.py

@@ -157,6 +157,10 @@ def violations(self, src_path):
                 self.violations_dict = self.driver.parse_reports(self.reports)
                 return self.violations_dict[src_path]
 
+            if not os.path.exists(src_path):
+                self.violations_dict[src_path] = []
+                return self.violations_dict[src_path]
+
             if self.driver_tool_installed is None:
                 self.driver_tool_installed = self.driver.installed()
             if not self.driver_tool_installed:
@@ -166,8 +170,7 @@ def violations(self, src_path):
             if self.options:
                 for arg in self.options.split():
                     command.append(arg)
-            if os.path.exists(src_path):
-                command.append(src_path.encode(sys.getfilesystemencoding()))
+            command.append(src_path.encode(sys.getfilesystemencoding()))
 
             stdout, stderr = execute(command, self.driver.exit_codes)
             output = stderr if self.driver.output_stderr else stdout

tests/test_violations_reporter.py

@@ -1586,12 +1586,15 @@ def test_quality(self, process_patcher):
 
 
 class TestPylintQualityReporterTest:
+    @pytest.mark.disable_all_files_exist
     def test_no_such_file(self):
+        file_paths = ["ajshdjlasdhajksdh.py"]
         quality = QualityReporter(PylintDriver())
 
         # Expect that we get no results
-        result = quality.violations("")
-        assert result == []
+        for path in file_paths:
+            result = quality.violations(path)
+            assert result == []
 
     def test_no_python_file(self):
         quality = QualityReporter(PylintDriver())
@@ -2181,6 +2184,15 @@ def test_quality_reporter(self, mocker):
 
         assert mock_stderr.getvalue() == "pycodestyle path/to/file.py"
 
+    @pytest.mark.disable_all_files_exist
+    def test_file_does_not_exist(self):
+        quality = QualityReporter(pycodestyle_driver)
+        file_paths = ["ajshdjlasdhajksdh.py"]
+        # Expect that we get no results because that file does not exist
+        for path in file_paths:
+            result = quality.violations(path)
+            assert result == []
+
 
 class TestCppcheckQualityDriverTest:
     """Tests for cppcheck quality driver."""