chore: use raise..from for chained exceptions (python-gitlab#939)

nejch · nejch · commit 79fef262c3e0 · 2020-03-30T01:19:23.000+02:00
diff --git a/gitlab/__init__.py b/gitlab/__init__.py
@@ -605,10 +605,10 @@ def http_get(self, path, query_data=None, streamed=False, raw=False, **kwargs):
         ):
             try:
                 return result.json()
-            except Exception:
+            except Exception as e:
                 raise GitlabParsingError(
                     error_message="Failed to parse the server message"
-                )
+                ) from e
         else:
             return result
 
@@ -685,8 +685,10 @@ def http_post(self, path, query_data=None, post_data=None, files=None, **kwargs)
         try:
             if result.headers.get("Content-Type", None) == "application/json":
                 return result.json()
-        except Exception:
-            raise GitlabParsingError(error_message="Failed to parse the server message")
+        except Exception as e:
+            raise GitlabParsingError(
+                error_message="Failed to parse the server message"
+            ) from e
         return result
 
     def http_put(self, path, query_data=None, post_data=None, files=None, **kwargs):
@@ -721,8 +723,10 @@ def http_put(self, path, query_data=None, post_data=None, files=None, **kwargs):
         )
         try:
             return result.json()
-        except Exception:
-            raise GitlabParsingError(error_message="Failed to parse the server message")
+        except Exception as e:
+            raise GitlabParsingError(
+                error_message="Failed to parse the server message"
+            ) from e
 
     def http_delete(self, path, **kwargs):
         """Make a PUT request to the Gitlab server.
@@ -788,8 +792,10 @@ def _query(self, url, query_data=None, **kwargs):
 
         try:
             self._data = result.json()
-        except Exception:
-            raise GitlabParsingError(error_message="Failed to parse the server message")
+        except Exception as e:
+            raise GitlabParsingError(
+                error_message="Failed to parse the server message"
+            ) from e
 
         self._current = 0
 
diff --git a/gitlab/config.py b/gitlab/config.py
@@ -60,18 +60,18 @@ def __init__(self, gitlab_id=None, config_files=None):
         if self.gitlab_id is None:
             try:
                 self.gitlab_id = self._config.get("global", "default")
-            except Exception:
+            except Exception as e:
                 raise GitlabIDError(
                     "Impossible to get the gitlab id (not specified in config file)"
-                )
+                ) from e
 
         try:
             self.url = self._config.get(self.gitlab_id, "url")
-        except Exception:
+        except Exception as e:
             raise GitlabDataError(
                 "Impossible to get gitlab informations from "
                 "configuration (%s)" % self.gitlab_id
-            )
+            ) from e
 
         self.ssl_verify = True
         try:
diff --git a/gitlab/exceptions.py b/gitlab/exceptions.py
@@ -270,7 +270,7 @@ def wrapped_f(*args, **kwargs):
             try:
                 return f(*args, **kwargs)
             except GitlabHttpError as e:
-                raise error(e.error_message, e.response_code, e.response_body)
+                raise error(e.error_message, e.response_code, e.response_body) from e
 
         return wrapped_f
 
diff --git a/gitlab/tests/test_exceptions.py b/gitlab/tests/test_exceptions.py
@@ -0,0 +1,19 @@
+import unittest
+
+from gitlab import exceptions
+
+
+class TestExceptions(unittest.TestCase):
+    def test_error_raises_from_http_error(self):
+        """Methods decorated with @on_http_error should raise from GitlabHttpError."""
+
+        class TestError(Exception):
+            pass
+
+        @exceptions.on_http_error(TestError)
+        def raise_error_from_http_error():
+            raise exceptions.GitlabHttpError
+
+        with self.assertRaises(TestError) as context:
+            raise_error_from_http_error()
+        self.assertIsInstance(context.exception.__cause__, exceptions.GitlabHttpError)
diff --git a/gitlab/v4/objects.py b/gitlab/v4/objects.py
@@ -2720,14 +2720,14 @@ def set_release_description(self, description, **kwargs):
                     path, post_data=data, **kwargs
                 )
             except exc.GitlabHttpError as e:
-                raise exc.GitlabCreateError(e.response_code, e.error_message)
+                raise exc.GitlabCreateError(e.response_code, e.error_message) from e
         else:
             try:
                 server_data = self.manager.gitlab.http_put(
                     path, post_data=data, **kwargs
                 )
             except exc.GitlabHttpError as e:
-                raise exc.GitlabUpdateError(e.response_code, e.error_message)
+                raise exc.GitlabUpdateError(e.response_code, e.error_message) from e
         self.release = server_data
 
 
