Add round_digits parameter to data_regression (#177)

Fix #170
Fix #159

Co-authored-by: Bruno Oliveira <[email protected]>

CHANGELOG.rst

@@ -1,7 +1,8 @@
 UNRELEASED
 ----------
 
-* `#132 <https://github.com/ESSS/pytest-regressions/pull/132>`__: Add documentation for specifying custom data directories.
+* `#132 <https://github.com/ESSS/pytest-regressions/pull/132>`__: Added documentation for specifying custom data directories.
+* `#177 <https://github.com/ESSS/pytest-regressions/pull/177>`__: Added new ``round_digits`` to ``data_regression.check``, which when given will round all float values to the given number of dicts (recursively) before saving the data to disk.
 
 2.5.0 (2023-08-31)
 ------------------

src/pytest_regressions/common.py

@@ -3,7 +3,11 @@
 from pathlib import Path
 from typing import Callable
 from typing import List
+from typing import MutableMapping
+from typing import MutableSequence
 from typing import Optional
+from typing import TypeVar
+from typing import Union
 
 import pytest
 
@@ -188,3 +192,33 @@ def make_location_message(banner: str, filename: Path, aux_files: List[str]) ->
             else:
                 dump_aux_fn(Path(obtained_filename))
                 raise
+
+
+T = TypeVar("T", bound=Union[MutableSequence, MutableMapping])
+
+
+def round_digits_in_data(data: T, digits: int) -> T:
+    """
+    Recursively round the values of any float value in a collection to the given number of digits. The rounding is done in-place.
+
+    :param data:
+        The collection to round.
+
+    :param digits:
+        The number of digits to round to.
+
+    :return:
+        The collection with all float values rounded to the given precision.
+        Note that the rounding is done in-place, so this return value only exists
+        because we use the function recursively.
+    """
+    # Change the generator depending on the collection type.
+    generator = enumerate(data) if isinstance(data, MutableSequence) else data.items()
+    for k, v in generator:
+        if isinstance(v, (MutableSequence, MutableMapping)):
+            data[k] = round_digits_in_data(v, digits)
+        elif isinstance(v, float):
+            data[k] = round(v, digits)
+        else:
+            data[k] = v
+    return data

src/pytest_regressions/data_regression.py

@@ -11,6 +11,7 @@
 
 from .common import check_text_files
 from .common import perform_regression_check
+from .common import round_digits_in_data
 
 
 class DataRegressionFixture:
@@ -32,6 +33,7 @@ def check(
         data_dict: Dict[str, Any],
         basename: Optional[str] = None,
         fullpath: Optional["os.PathLike[str]"] = None,
+        round_digits: Optional[int] = None,
     ) -> None:
         """
         Checks the given dict against a previously recorded version, or generate a new file.
@@ -46,13 +48,18 @@ def check(
             will ignore ``datadir`` fixture when reading *expected* files but will still use it to
             write *obtained* files. Useful if a reference file is located in the session data dir for example.
 
+        :param round_digits:
+            If given, round all floats in the dict to the given number of digits.
+
         ``basename`` and ``fullpath`` are exclusive.
         """
         __tracebackhide__ = True
 
+        if round_digits is not None:
+            round_digits_in_data(data_dict, round_digits)
+
         def dump(filename: Path) -> None:
             """Dump dict contents to the given filename"""
-            import yaml
 
             dumped_str = yaml.dump_all(
                 [data_dict],

tests/test_data_regression.py

@@ -1,6 +1,7 @@
 import sys
 from textwrap import dedent
 
+import pytest
 import yaml
 
 from pytest_regressions.testing import check_regression_fixture_workflow
@@ -38,6 +39,24 @@ def dump_scalar(dumper, scalar):
     data_regression.check(contents)
 
 
+def test_round_digits(data_regression):
+    """Example including float numbers and check rounding capabilities."""
+    contents = {
+        "content": {"value1": "toto", "value": 1.123456789},
+        "values": [1.12345, 2.34567],
+        "value": 1.23456789,
+    }
+    data_regression.check(contents, round_digits=2)
+
+    with pytest.raises(AssertionError):
+        contents = {
+            "content": {"value1": "toto", "value": 1.2345678},
+            "values": [1.13456, 2.45678],
+            "value": 1.23456789,
+        }
+        data_regression.check(contents, round_digits=2)
+
+
 def test_usage_workflow(pytester, monkeypatch):
     monkeypatch.setattr(
         sys, "testing_get_data", lambda: {"contents": "Foo", "value": 10}, raising=False

tests/test_data_regression/test_round_digits.yml

@@ -0,0 +1,7 @@
+content:
+  value: 1.12
+  value1: toto
+value: 1.23
+values:
+- 1.12
+- 2.35