Exception Handling - Created custom exception classes (#50)

* Add base exceptions for error handling

* update pyright version for pipeline

* reformatting for black

* using ParsingError + unit tests

* type stub for pytest

* Fixed pyright errors with pytest + formatting for black

* Renamed DeserializationError

Co-authored-by: Yefri Gaitan <yefrigaitan@gmail.com>

tests/json_test.py

@@ -4,9 +4,11 @@
 from hypothesis import given
 from volga.fields import Int, Bool, Float, Null, Str
 from volga.json import deserialize
+from volga.exceptions import ParsingError
 
 
 import json
+import pytest  # type: ignore
 
 
 @given(st.integers())
@@ -36,24 +38,21 @@ def test_serialize_none(x: None):
     assert deserialize(json.dumps(x), Null) == None
 
 
-# class User(Schema):
-#     # name: Str
-#     age: Int
-#     score: Float
-#     verified: Bool
-
-
-# @given(
-#     a=st.integers(), s=st.floats(allow_infinity=False, allow_nan=False), v=st.booleans()
-# )
-# def test_deserialize_user(a: int, s: float, v: bool):
-#     userJSON = (
-#         '{"age":'
-#         + json.dumps(a)
-#         + ',"score":'
-#         + json.dumps(s)
-#         + ',"verified":'
-#         + json.dumps(v)
-#         + "}"
-#     )
-#     assert deserialize(userJSON, User) == User(age=a, score=s, verified=v)
+def test_parsing_error_int():
+    with pytest.raises(ParsingError):  # type: ignore
+        deserialize("Not an int", Int)
+
+
+def test_parsing_error_bool():
+    with pytest.raises(ParsingError):  # type: ignore
+        deserialize("Not a bool", Bool)
+
+
+def test_parsing_error_float():
+    with pytest.raises(ParsingError):  # type: ignore
+        deserialize("Not a float", Float)
+
+
+def test_parsing_error_str():
+    with pytest.raises(ParsingError):  # type: ignore
+        deserialize(0, Str)  # type: ignore

typings/pytest/__init__.pyi

@@ -0,0 +1,34 @@
+"""
+This type stub file was generated by pyright.
+"""
+
+from _pytest import __version__
+from _pytest.assertion import register_assert_rewrite
+from _pytest.compat import _setup_collect_fakemodule
+from _pytest.config import ExitCode, UsageError, cmdline, hookimpl, hookspec, main
+from _pytest.debugging import pytestPDB as __pytestPDB
+from _pytest.fixtures import fillfixtures as _fillfuncargs, fixture, yield_fixture
+from _pytest.freeze_support import freeze_includes
+from _pytest.main import Session
+from _pytest.mark import MARK_GEN as mark, param
+from _pytest.nodes import Collector, File, Item
+from _pytest.outcomes import exit, fail, importorskip, skip, xfail
+from _pytest.python import Class, Function, Instance, Module, Package
+from _pytest.python_api import approx, raises
+from _pytest.recwarn import deprecated_call, warns
+from _pytest.warning_types import (
+    PytestAssertRewriteWarning,
+    PytestCacheWarning,
+    PytestCollectionWarning,
+    PytestConfigWarning,
+    PytestDeprecationWarning,
+    PytestExperimentalApiWarning,
+    PytestUnhandledCoroutineWarning,
+    PytestUnknownMarkWarning,
+    PytestWarning,
+)
+
+"""
+pytest: unit and functional testing with Python.
+"""
+set_trace = __pytestPDB.set_trace

typings/pytest/__main__.pyi

@@ -0,0 +1,8 @@
+"""
+This type stub file was generated by pyright.
+"""
+
+"""
+pytest entry point
+"""
+if __name__ == "__main__": ...

volga/exceptions.py

@@ -0,0 +1,16 @@
+class VolgaError(Exception):
+    """Base class for all volga-related errors."""
+
+    pass
+
+
+class DeserializationError(VolgaError):
+    """Raised during serialization errors when parsing or building object instances."""
+
+    pass
+
+
+class ParsingError(VolgaError):
+    """Raised during deserialization errors when parsing object instances."""
+
+    pass

volga/json.py

@@ -11,6 +11,7 @@
 
 
 import volga.format as format
+import volga.exceptions as exceptions
 
 RE_FLAGS = re.VERBOSE | re.MULTILINE | re.DOTALL
 
@@ -48,7 +49,7 @@ def _parse_bool(self) -> bool:
             self.idx += 6
             return False
         else:
-            raise RuntimeError("Expected bool")
+            raise exceptions.ParsingError("Expected bool")
 
     def _parse_float(self) -> float:
 
@@ -61,7 +62,7 @@ def _parse_float(self) -> float:
             self.idx = match.end()
             return n
         else:
-            raise RuntimeError("Expected float")
+            raise exceptions.ParsingError("Expected float")
 
     def _parse_int(self) -> int:
 
@@ -70,24 +71,27 @@ def _parse_int(self) -> int:
         if match:
             integer, frac, exp = match.groups()
             if frac or exp:
-                raise RuntimeError("Expected integer value.")
+                raise exceptions.ParsingError("Expected integer value.")
             else:
                 n = int(integer)
             self.idx = match.end()
             return n
         else:
-            raise RuntimeError("Expected int")
+            raise exceptions.ParsingError("Expected int")
 
     def _parse_str(self) -> str:
 
+        if type(self.s) != str:
+            raise exceptions.ParsingError("Expected String, not " + str(type(self.s)))
+
         if self.s[self.idx] != '"':
-            raise RuntimeError("Expected String")
+            raise exceptions.ParsingError("Expected String")
 
         # skip past first "
         chunk = STRING_RE.match(self.s, self.idx + 1)
 
         if chunk is None:
-            raise RuntimeError("Unterminated string.")
+            raise exceptions.ParsingError("Unterminated string.")
 
         content, _ = chunk.groups()
         self.idx = chunk.end()
@@ -101,7 +105,7 @@ def _parse_none(self) -> None:
             self.idx += 5
             return None
         else:
-            raise RuntimeError("Expected null")
+            raise exceptions.ParsingError("Expected null")
 
     def __deserialize_str__(
         self, constructor: Type[types.supportsDeser]
@@ -115,7 +119,7 @@ def __deserialize_dict__(
         res = {}
 
         if self.s[self.idx] != "{":
-            raise RuntimeError("Expected dict")
+            raise exceptions.ParsingError("Expected dict")
 
         # for each attribute in the schema
 
@@ -126,15 +130,15 @@ def __deserialize_dict__(
             chunk = STRING_RE.match(self.s, self.idx + 2)
 
             if chunk is None:
-                raise RuntimeError("Expected key string.")
+                raise exceptions.ParsingError("Expected key string.")
 
             parsed_key, _ = chunk.groups()
             self.idx = chunk.end()
 
             assert parsed_key == key
 
             if self.s[self.idx] != ":":
-                raise RuntimeError("Expected value for key")
+                raise exceptions.ParsingError("Expected value for key")
             self.idx += 1
 
             # parse the value according to schema