Add option to skip none values when printing a configuration (#24)

Author: gahjelle

src/configaroo/configuration.py

@@ -221,7 +221,11 @@ def to_flat_dict(self, _prefix: str = "") -> dict[str, Any]:
 
 
 def print_configuration(
-    config: Configuration | BaseModel, section: str | None = None, indent: int = 4
+    config: Configuration | BaseModel,
+    section: str | None = None,
+    *,
+    skip_none: bool = False,
+    indent: int = 4,
 ) -> None:
     """Pretty print a configuration.
 
@@ -232,18 +236,22 @@ def print_configuration(
     )
     if section is None:
         _print, _escape = _get_rich_print()
-        return _print_dict_as_tree(cfg, indent=indent, _print=_print, _escape=_escape)
+        return _print_dict_as_tree(
+            cfg, skip_none=skip_none, indent=indent, _print=_print, _escape=_escape
+        )
 
     cfg_section = cfg.get(section)
     if cfg_section is None:
         message = f"'{type(cfg).__name__}' has no section '{section}'"
         raise KeyError(message) from None
 
     if isinstance(cfg_section, Configuration):
-        return print_configuration(cfg_section, indent=indent)
+        return print_configuration(cfg_section, skip_none=skip_none, indent=indent)
 
     *_, key = section.split(".")
-    return print_configuration(Configuration({key: cfg_section}), indent=indent)
+    return print_configuration(
+        Configuration({key: cfg_section}), skip_none=skip_none, indent=indent
+    )
 
 
 def _get_rich_print() -> tuple[
@@ -264,13 +272,17 @@ def _get_rich_print() -> tuple[
 
 def _print_dict_as_tree(
     data: dict[str, Any] | UserDict[str, Any] | Configuration,
+    *,
+    skip_none: bool = False,
     indent: int = 4,
     current_indent: int = 0,
     _print: Callable[[str], None] = print,
     _escape: Callable[[str], str] = str,
 ) -> None:
     """Print a nested dictionary as a tree."""
     for key, value in data.items():
+        if skip_none and value is None:
+            continue
         if isinstance(value, dict | UserDict | Configuration):
             _print(" " * current_indent + f"- {key}")
             _print_dict_as_tree(

tests/test_print.py

@@ -100,3 +100,27 @@ def test_printing_of_rich_markup() -> None:
     """Test that a config value containing malformed Rich markup can be printed."""
     config = Configuration({"markup": "[/]"})
     print_configuration(config)
+
+
+def test_print_keeping_none(
+    capsys: pytest.CaptureFixture[str], config: Configuration
+) -> None:
+    """Test that None-values are kept in printout by default."""
+    print_configuration(config | {"none": None})
+    stdout = capsys.readouterr().out
+    lines = stdout.splitlines()
+
+    assert "- none: None" in lines
+    assert "- number: 42" in lines
+
+
+def test_print_skipping_none(
+    capsys: pytest.CaptureFixture[str], config: Configuration
+) -> None:
+    """Test that None-values are skipped in printout if asked for."""
+    print_configuration(config | {"none": None}, skip_none=True)
+    stdout = capsys.readouterr().out
+    lines = stdout.splitlines()
+
+    assert "- none: None" not in lines
+    assert "- number: 42" in lines