validation on translation dicts (#160)

CHANGELOG.rst

@@ -27,6 +27,11 @@ Changed
     sub-package.
   * Sort tests into feature and unit tests.
 
+* Extra translations dictionaries are now checked so that keys must be
+  integers and values must consist of only English alphabetic
+  characters.
+  [`#157 <https://github.com/jagerber48/sciform/issues/157>`_]
+
 ----
 
 0.35.0 (2024-02-16)

docs/source/options.rst

@@ -248,6 +248,9 @@ force that exponent to not be translated.
 >>> print(formatter(3e-9))
 3e-09
 
+Keys into the extra translations dictionaries must be integers and
+values must consist of only English alphabetic characters.
+
 Two helper options exist to add additional SI prefix translations
 corresponding to::
 

src/sciform/options/validation.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import re
 from typing import TYPE_CHECKING, get_args
 
 from sciform.options import option_types
@@ -19,6 +20,7 @@ def validate_options(
     validate_sig_fig_round_mode(options)
     validate_exp_val(options)
     validate_separator_options(options)
+    validate_extra_translations(options)
 
 
 def validate_sig_fig_round_mode(
@@ -99,3 +101,28 @@ def validate_separator_options(
             f"not {options.lower_separator}."
         )
         raise ValueError(msg)
+
+
+def validate_extra_translations(
+    options: InputOptions | PopulatedOptions | FinalizedOptions,
+) -> None:
+    """Validate translation dictionary have int keys and alphabetic values."""
+    translations_dicts = [
+        options.extra_si_prefixes,
+        options.extra_iec_prefixes,
+        options.extra_parts_per_forms,
+    ]
+
+    for translation_dict in translations_dicts:
+        if translation_dict is not None:
+            for key, value in translation_dict.items():
+                if not isinstance(key, int):
+                    msg = f'Translation dictionary keys must be integers, not "{key}".'
+                    raise TypeError(msg)
+                if value is not None and not re.match(r"[a-zA-Z]+", value):
+                    msg = (
+                        f"Translation dictionary values may only contain lower or "
+                        f"uppercase ASCII characters from the English alphabet, not "
+                        f'"{value}".'
+                    )
+                    raise ValueError(msg)

tests/unit/test_invalid_options.py

@@ -278,3 +278,17 @@ def test_parse_mantissa_from_ascii_exp_str(self):
             parse_mantissa_from_ascii_exp_str,
             "1.23c+04",
         )
+
+    def test_invalid_translation_key(self):
+        self.assertRaises(
+            TypeError,
+            Formatter,
+            extra_si_prefixes={"3": "k"},
+        )
+
+    def test_invalid_translation_value(self):
+        self.assertRaises(
+            ValueError,
+            Formatter,
+            extra_si_prefixes={-10: "Å"},
+        )