add io module

for writing to and reading from the file-system

Author: Kilo59

app/io.py

@@ -0,0 +1,28 @@
+"""app.io.py"""
+import json
+import pathlib
+from typing import Dict, Union
+
+HERE = pathlib.Path(__file__)
+DATA = HERE.joinpath("..", "data").resolve()
+
+
+def save(
+    name: str, content: Union[str, Dict], write_mode: str = "w", indent: int = 2, **json_dumps_kwargs
+) -> pathlib.Path:
+    """Save content to a file. If content is a dictionary, use json.dumps()."""
+    path = DATA / name
+    if isinstance(content, dict):
+        content = json.dumps(content, indent=indent, **json_dumps_kwargs)
+    with open(DATA / name, mode=write_mode) as f_out:
+        f_out.write(content)
+    return path
+
+
+def load(name: str, **json_kwargs) -> Union[str, Dict]:
+    """Loads content from a file. If file ends with '.json', call json.load() and return a Dictionary."""
+    path = DATA / name
+    with open(path) as f_in:
+        if path.suffix == ".json":
+            return json.load(f_in, **json_kwargs)
+        return f_in.read()

tests/test_io.py

@@ -0,0 +1,39 @@
+"""test.test_io.py"""
+import string
+
+import pytest
+
+import app.io
+
+
+@pytest.mark.parametrize(
+    "name, content, kwargs",
+    [
+        ("test_file.txt", string.ascii_lowercase, {}),
+        ("test_json_file.json", {"a": 0, "b": 1, "c": 2}, {}),
+        ("test_custom_json.json", {"z": -1, "b": 1, "y": -2, "a": 0}, {"indent": 4, "sort_keys": True}),
+    ],
+)
+def test_save(tmp_path, name, content, kwargs):
+    test_path = tmp_path / name
+    assert not test_path.exists()
+
+    result = app.io.save(test_path, content, **kwargs)
+    assert result == test_path
+    assert test_path.exists()
+
+
+@pytest.mark.parametrize(
+    "name, content, kwargs",
+    [
+        ("test_file.txt", string.ascii_lowercase, {}),
+        ("test_json_file.json", {"a": 0, "b": 1, "c": 2}, {}),
+        ("test_custom_json.json", {"z": -1, "b": 1, "y": -2, "a": 0}, {"indent": 4, "sort_keys": True}),
+    ],
+)
+def test_round_trip(tmp_path, name, content, kwargs):
+    test_path = tmp_path / name
+    assert not test_path.exists()
+
+    app.io.save(test_path, content, **kwargs)
+    assert app.io.load(test_path) == content