Raise CannotParseBodyErrorAsJson when the body is invalid JSON.

src/requtests/parsed_request.py

@@ -1,8 +1,15 @@
 import json
+from json import JSONDecodeError
 from typing import Any, Dict, List, Optional, Union
 from urllib.parse import parse_qs, urlparse
 
 
+class CannotParseBodyAsJson(RuntimeError):
+    def __init__(self, error):
+        super().__init__(error)
+        self.error = error
+
+
 class ParsedRequest:
     def __init__(self, prepared_request):
         self.prepared_request = prepared_request
@@ -29,7 +36,10 @@ def json(self) -> Any:
         """
         The body of the prepared request, parsed as JSON.
         """
-        return json.loads(self.prepared_request.body)
+        try:
+            return json.loads(self.prepared_request.body)
+        except (TypeError, JSONDecodeError) as e:
+            raise CannotParseBodyAsJson(e)
 
     @property
     def method(self) -> str:

tests/parsed_request_test.py

@@ -1,7 +1,8 @@
 from json import JSONDecodeError
-import re
 import pytest
+import re
 from requtests import ParsedRequest
+from requtests.parsed_request import CannotParseBodyAsJson
 from tests.test_utils import build_request
 
 
@@ -50,15 +51,19 @@ def test_parsing_a_prepared_request(prepared_request):
 def test_json_with_an_empty_body(parsed_request):
     parsed_request.prepared_request.body = None
     expected_message = "the JSON object must be str, bytes or bytearray, not NoneType"
-    with pytest.raises(TypeError, match=expected_message):
-        assert parsed_request.json
+    with pytest.raises(CannotParseBodyAsJson, match=expected_message) as exc_info:
+        parsed_request.json
+    underlying_error = exc_info.value.error
+    assert isinstance(underlying_error, TypeError)
 
 
 def test_json_with_an_invalid_json_body(parsed_request):
     parsed_request.prepared_request.body = '{"broken": "json'
     expected_message = re.escape("Unterminated string starting at: line 1 column 12 (char 11)")
-    with pytest.raises(JSONDecodeError, match=expected_message):
-        assert parsed_request.json
+    with pytest.raises(CannotParseBodyAsJson, match=expected_message) as exc_info:
+        parsed_request.json
+    underlying_error = exc_info.value.error
+    assert isinstance(underlying_error, JSONDecodeError)
 
 
 def test_text_with_an_empty_body(parsed_request):