fix(checks): make am_pm check case sensitive

proselint/checks/dates_times/am_pm.py

@@ -19,7 +19,8 @@ def check_lowercase_periods(text):
     err = "dates_times.am_pm.lowercase_periods"
     msg = "With lowercase letters, the periods are standard."
 
-    return existence_check(text, [r"\d{1,2} ?[ap]m"], err, msg)
+    return existence_check(text, [r"\d{1,2} ?[ap]m"], err, msg,
+                           ignore_case=False)
 
 
 @memoize

tests/test_dates_times_am_pm.py

@@ -1,5 +1,4 @@
 """Tests for dates_times.am_pm check."""
-from __future__ import absolute_import
 
 from proselint.checks.dates_times import am_pm as chk
 
@@ -29,6 +28,8 @@ def test_smoke_check_lowercase_periods(self):
             "It happened at 7 a.m.") == []
         assert chk.check_lowercase_periods(
             "It happened at 7 am.") != []
+        assert chk.check_lowercase_periods(
+            "On Wed, Sep 21, 2016 at 11:42 AM -0400, X wrote:") == []
 
     def test_smoke_check_spacing(self):
         """Basic smoke test.
@@ -65,9 +66,9 @@ def test_smoke_check_redundancy(self):
         dates_times.am_pm.check_redundancy.
 
         """
-        assert chk.check_redundancy(
-            "Basic smoke phrase without issues.") == []
-        assert chk.check_redundancy(
-            "It happened at 7 a.m.") == []
-        assert chk.check_redundancy(
-            "It happened at 7a.m. in the morning.") != []
+        assert len(chk.check_redundancy(
+            "Basic smoke phrase without issues.")) == 0
+        assert len(chk.check_redundancy(
+            "It happened at 7 a.m.")) == 0
+        assert len(chk.check_redundancy(
+            "It happened at 7a.m. in the morning.")) == 1

tests/test_existence_check.py

@@ -41,6 +41,9 @@ def test_multiple_matches(self):
         assert len(
             chk("""ABC and abc are as easy as 123""",
                 self.L, self.err, self.msg, ignore_case=True)) == 2
+        assert len(
+            chk("""ABC and abc are as easy as 123""",
+                self.L, self.err, self.msg, ignore_case=False)) == 1
         assert chk(
             """abcabc are easy as 123""", self.L, self.err, self.msg) == []