test_typeddict.py

Overview

The [test_typeddict.py](/projects/287/68206) file contains a simple test case focused on verifying the JSON serialization of Python `TypedDict` objects using the `orjson` library. The primary functionality demonstrated here is that an instance of a `TypedDict` can be serialized correctly to a JSON byte string by [orjson.dumps()](/projects/287/67747).

This file serves as a minimal validation or example for compatibility between `TypedDict` (a type hinting feature introduced in Python 3.8 and backported via `typing_extensions`) and the `orjson` serialization library.

Classes and Methods

Class: TestTypedDict

A test class designed to group related test(s) for `TypedDict` serialization.

Method: test_typeddict(self)

• Purpose:
  To verify that an instance of a TypedDict subclass can be serialized to JSON using orjson.dumps() producing the expected byte string output.

• Parameters:

  • self: The instance of the TestTypedDict class.

• Returns:

  • None.
    The method uses an assertion to confirm the serialization result.

• Description:
  Inside this method, a local TypedDict subclass TypedDict1 is defined with two fields:

  • a of type str

  • b of type int

  An object `obj` of type [TypedDict1](/projects/287/67762) is created with values `a="a"` and `b=1`. The method asserts that serializing `obj` using [orjson.dumps(obj)](/projects/287/67747) matches the expected JSON byte string `b'{"a":"a","b":1}'`.

• Usage Example:

  test = TestTypedDict()
  test.test_typeddict()
  

  Running this method will raise an AssertionError if orjson does not serialize the TypedDict instance as expected.

Implementation Details

• Conditional Import for TypedDict:
  The file attempts to import TypedDict from the standard typing module (available in Python 3.8+). If unavailable (e.g., on older Python versions), it falls back to importing TypedDict from typing_extensions. This ensures compatibility across Python versions.

• orjson Serialization:
  orjson is a fast JSON library for Python that serializes Python objects to JSON bytes. Here it is used to serialize a TypedDict instance, which is essentially a dictionary with static type checking.

• Test Scope:
  This is a minimal test focused only on serialization correctness. It does not test deserialization or other features of TypedDict.

Interaction with Other System Components

• orjson library:
  This file tests compatibility between TypedDict and orjson. It depends on orjson's capability to serialize dictionary-like objects.

• Typing infrastructure:
  It leverages Python's typing system to define TypedDict for structured dictionary types.

• Testing integration:
  Although not explicitly stated, the structure suggests this is intended for use with a test runner (e.g., pytest or unittest) to automate this test as part of a test suite validating serialization behavior.

Mermaid Class Diagram

classDiagram
    class TestTypedDict {
        +test_typeddict()
    }

Summary

• This file provides a single test validating that TypedDict instances serialize correctly using orjson.

• It ensures backward compatibility with Python versions lacking built-in TypedDict.

• It is useful as a regression or compatibility test within a larger test suite for JSON serialization functionality.

• The implementation is straightforward and focuses exclusively on serialization correctness for a defined typed dictionary.

End of test_typeddict.py documentation.