fix: give alternate unit suffixes their own keys

bin/units_from_xls.py

@@ -146,6 +146,17 @@ def __call__(self, name_or_suffix):
 '''
 
 SHEET_NAME = 'Annex II & Annex III'
+
+# Module-level names for alternate symbols, keyed by (common code, symbol).
+# Only four rows in the spreadsheet list more than one symbol, so an explicit
+# table is cheaper and more readable than deriving names from the symbol.  An
+# alternate symbol that is not listed here is still appended to ALL_UNITS and
+# so remains reachable through units.Unit('<symbol>'); it just gets no
+# module-level name.
+ALIAS_UNIT_KEYS = {
+    ('P1', 'pct'): 'PERCENT_PCT',
+}
+
 UNIT_KEY_REPLACEMENTS = {
     ' ': '_',
     ',': '_',
@@ -235,11 +246,25 @@ def unit_defs_from_sheet(sheet, column_names):
         continue
       seen.add(key)
 
-      # Split on ' or ' to support the units like '% or pct'
-      for suffix in suffix.split(' or '):
-        yield "%s = UnitDescriptor('%s', '%s', '''%s''')\n" % (key, name, code,
-                                                               suffix)
-        yield 'ALL_UNITS.append(%s)\n' % key
+      # Split on ' or ' to support units like '% or pct'.  The first symbol
+      # listed is the primary one and keeps the canonical key.  Alternate
+      # symbols are appended to ALL_UNITS so they stay reachable via
+      # units.Unit('<suffix>'), but they only get a module-level name when
+      # ALIAS_UNIT_KEYS says so -- deriving one from the suffix produces
+      # names like KILOGRAM_PER_LITRE_KG_PER_L that nobody would type.
+      for idx, suffix in enumerate(suffix.split(' or ')):
+        if idx == 0:
+          alias_key = key
+        else:
+          alias_key = ALIAS_UNIT_KEYS.get((code, suffix))
+        if alias_key is None:
+          yield "ALL_UNITS.append(UnitDescriptor('%s', '%s', '''%s'''))\n" % (
+              name, code, suffix)
+        else:
+          yield "%s = UnitDescriptor('%s', '%s', '''%s''')\n" % (alias_key,
+                                                                 name, code,
+                                                                 suffix)
+          yield 'ALL_UNITS.append(%s)\n' % alias_key
 
   except xlrd.XLRDError:
     sys.stdout.write('Unable to process the .xls file.')

openhtf/util/units.py

@@ -659,8 +659,7 @@ class UnitDescriptor(
 ALL_UNITS.append(KILOGRAM_PER_CUBIC_DECIMETRE)
 KILOGRAM_PER_LITRE = UnitDescriptor('kilogram per litre', 'B35', '''kg/l''')
 ALL_UNITS.append(KILOGRAM_PER_LITRE)
-KILOGRAM_PER_LITRE = UnitDescriptor('kilogram per litre', 'B35', '''kg/L''')
-ALL_UNITS.append(KILOGRAM_PER_LITRE)
+ALL_UNITS.append(UnitDescriptor('kilogram per litre', 'B35', '''kg/L'''))
 CALORIE_THERMOCHEMICAL_PER_GRAM = UnitDescriptor('calorie (thermochemical) per gram', 'B36', '''calth/g''')
 ALL_UNITS.append(CALORIE_THERMOCHEMICAL_PER_GRAM)
 KILOGRAM_FORCE = UnitDescriptor('kilogram-force', 'B37', '''kgf''')
@@ -1379,8 +1378,7 @@ class UnitDescriptor(
 ALL_UNITS.append(DRY_TON)
 DECITONNE = UnitDescriptor('decitonne', 'DTN', '''dt''')
 ALL_UNITS.append(DECITONNE)
-DECITONNE = UnitDescriptor('decitonne', 'DTN', '''dtn''')
-ALL_UNITS.append(DECITONNE)
+ALL_UNITS.append(UnitDescriptor('decitonne', 'DTN', '''dtn'''))
 DYNE = UnitDescriptor('dyne', 'DU', '''dyn''')
 ALL_UNITS.append(DYNE)
 PENNYWEIGHT = UnitDescriptor('pennyweight', 'DWT', '''''')
@@ -2255,8 +2253,7 @@ class UnitDescriptor(
 ALL_UNITS.append(FRENCH_GAUGE)
 RACK_UNIT = UnitDescriptor('rack unit', 'H80', '''U''')
 ALL_UNITS.append(RACK_UNIT)
-RACK_UNIT = UnitDescriptor('rack unit', 'H80', '''RU''')
-ALL_UNITS.append(RACK_UNIT)
+ALL_UNITS.append(UnitDescriptor('rack unit', 'H80', '''RU'''))
 MILLIMETRE_PER_MINUTE = UnitDescriptor('millimetre per minute', 'H81', '''mm/min''')
 ALL_UNITS.append(MILLIMETRE_PER_MINUTE)
 BIG_POINT = UnitDescriptor('big point', 'H82', '''bp''')
@@ -3647,8 +3644,8 @@ class UnitDescriptor(
 ALL_UNITS.append(PAGE_ELECTRONIC)
 PERCENT = UnitDescriptor('percent', 'P1', '''%''')
 ALL_UNITS.append(PERCENT)
-PERCENT = UnitDescriptor('percent', 'P1', '''pct''')
-ALL_UNITS.append(PERCENT)
+PERCENT_PCT = UnitDescriptor('percent', 'P1', '''pct''')
+ALL_UNITS.append(PERCENT_PCT)
 COULOMB_PER_METRE = UnitDescriptor('coulomb per metre', 'P10', '''C/m''')
 ALL_UNITS.append(COULOMB_PER_METRE)
 KILOWEBER = UnitDescriptor('kiloweber', 'P11', '''kWb''')

test/util/units_test.py

@@ -0,0 +1,56 @@
+# Copyright 2026 Google Inc. All Rights Reserved.
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Unit tests for the units module."""
+
+import unittest
+
+from openhtf.util import units
+
+
+class UnitsTest(unittest.TestCase):
+
+  def test_percent_keeps_primary_suffix(self):
+    """units.PERCENT must expose '%', not the 'pct' alias."""
+    self.assertEqual(units.PERCENT.suffix, '%')
+    self.assertEqual(units.PERCENT_PCT.suffix, 'pct')
+
+  def test_primary_symbol_wins_the_canonical_key(self):
+    """The first symbol listed in the sheet keeps the module-level name."""
+    for key, suffix in (
+        ('PERCENT', '%'),
+        ('KILOGRAM_PER_LITRE', 'kg/l'),
+        ('DECITONNE', 'dt'),
+        ('RACK_UNIT', 'U'),
+    ):
+      self.assertEqual(getattr(units, key).suffix, suffix)
+
+  def test_alternate_symbols_stay_reachable_by_lookup(self):
+    """Alternates have no module attribute but must still resolve."""
+    for suffix, name in (
+        ('pct', 'percent'),
+        ('kg/L', 'kilogram per litre'),
+        ('dtn', 'decitonne'),
+        ('RU', 'rack unit'),
+    ):
+      unit = units.Unit(suffix)
+      self.assertEqual(unit.suffix, suffix)
+      self.assertEqual(unit.name, name)
+
+  def test_lookup_by_every_suffix(self):
+    self.assertIs(units.Unit('%'), units.PERCENT)
+    self.assertIs(units.Unit('pct'), units.PERCENT_PCT)
+
+
+if __name__ == '__main__':
+  unittest.main()