Handle units containing 'degree' and 'per' correctly

inflect.py

@@ -1894,6 +1894,18 @@ def _plnoun(self, word, count=None):
                         lowersplit[:numword - 1] +
                         [self._plnoun(lowersplit[numword - 1], 2)] + lowersplit[numword:])
 
+        # Handle units given in degrees
+        if len(lowersplit) >= 2 and lowersplit[0] in ['degree']:
+            return ' '.join(
+                [self._plnoun(lowersplit[0])] + lowersplit[1:]
+            )
+        # only pluralize denominators in units
+        mo = search(r'(?P<denominator>.+)( (%s) .+)' % '|'.join(['per', 'a']), lowerword)
+        if mo:
+            index = len(mo.group('denominator'))
+            return '{}{}'.format(self._plnoun(lowerword[:index]),
+                                 lowerword[index:])
+
         lowersplit = lowerword.split('-')
         if len(lowersplit) >= 3:
             for numword in range(1, len(lowersplit) - 1):

tests/test_compounds.py

@@ -2,19 +2,56 @@
 
 import inflect
 
+p = inflect.engine()
 
-class TestCompounds(object):
-    def setup(self):
-        self.p = inflect.engine()
 
-    def test_compound_1(self):
-        eq_(self.p.singular_noun('hello-out-there'), 'hello-out-there')
+def test_compound_1():
+    eq_(p.singular_noun('hello-out-there'), 'hello-out-there')
 
-    def test_compound_2(self):
-        eq_(self.p.singular_noun('hello out there'), 'hello out there')
 
-    def test_compound_3(self):
-        eq_(self.p.singular_noun('continue-to-operate'), 'continue-to-operate')
+def test_compound_2():
+    eq_(p.singular_noun('hello out there'), 'hello out there')
 
-    def test_compound_4(self):
-        eq_(self.p.singular_noun('case of diapers'), 'case of diapers')
+
+def test_compound_3():
+    eq_(p.singular_noun('continue-to-operate'), 'continue-to-operate')
+
+
+def test_compound_4():
+    eq_(p.singular_noun('case of diapers'), 'case of diapers')
+
+
+def test_unit_handling_degree():
+    test_cases = {
+        'degree celsius': 'degrees celsius',
+        'degree fahrenheit': 'degrees fahrenheit',
+        'degree rankine': 'degrees rankine'
+    }
+    for singular, plural in test_cases.items():
+        eq_(p.plural(singular), plural)
+
+
+def test_unit_handling_fractional():
+    test_cases = {
+        'pound per square inch': 'pounds per square inch',
+        'pound-force per square inch': 'pound-forces per square inch',
+        'metre per second': 'metres per second',
+        'kilometre per hour': 'kilometres per hour',
+        'cubic metre per second': 'cubic metres per second',
+        'dollar a year': 'dollars a year',
+        # Correct pluralization of denominator
+        'foot per square second': 'feet per square second',
+        'mother-in-law per lifetime': 'mothers-in-law per lifetime'
+    }
+    for singular, plural in test_cases.items():
+        eq_(p.plural(singular), plural)
+
+
+def test_unit_handling_combined():
+    test_cases = {
+        # Heat transfer coefficient unit
+        'watt per square meter degree celsius': 'watts per square meter degree celsius',
+        'degree celsius per hour': 'degrees celsius per hour'
+    }
+    for singular, plural in test_cases.items():
+        eq_(p.plural(singular), plural)