key-ordering: Add more test cases and documentation

tests/rules/test_key_ordering.py

@@ -59,6 +59,55 @@ class KeyOrderingTestCase(RuleTestCase):
                    '  third:\n'
                    '    second: 2\n', conf)
 
+    def test_word_length(self):
+        conf = 'key-ordering: enable'
+        self.check('---\n'
+                   'a: 1\n'
+                   'ab: 1\n'
+                   'abc: 1\n', conf)
+        self.check('---\n'
+                   'a: 1\n'
+                   'abc: 1\n'
+                   'ab: 1\n', conf,
+                   problem=(4, 1))
+
+    def test_key_duplicates(self):
+        conf = ('key-duplicates: disable\n'
+                'key-ordering: enable')
+        self.check('---\n'
+                   'key: 1\n'
+                   'key: 2\n', conf)
+
+    def test_case(self):
+        conf = 'key-ordering: enable'
+        self.check('---\n'
+                   'T-shirt: 1\n'
+                   'T-shirts: 2\n'
+                   't-shirt: 3\n'
+                   't-shirts: 4\n', conf)
+        self.check('---\n'
+                   'T-shirt: 1\n'
+                   't-shirt: 2\n'
+                   'T-shirts: 3\n'
+                   't-shirts: 4\n', conf,
+                   problem=(4, 1))
+
+    def test_accents(self):
+        conf = 'key-ordering: enable'
+        self.check('---\n'
+                   'hair: true\n'
+                   'hais: true\n'
+                   'haïr: true\n'
+                   'haïssable: true\n', conf)
+        self.check('---\n'
+                   'haïr: true\n'
+                   'hais: true\n', conf,
+                   problem=(3, 1))
+        self.check('---\n'
+                   'haïr: true\n'
+                   'hais: true\n', conf,
+                   problem=(3, 1))
+
     def test_key_tokens_in_flow_sequences(self):
         conf = 'key-ordering: enable'
         self.check('---\n'

yamllint/rules/key_ordering.py

@@ -15,7 +15,9 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 """
-Use this rule to enforce alphabetical ordering of keys in mappings.
+Use this rule to enforce alphabetical ordering of keys in mappings. The sorting
+order uses the Unicode code point number. As a result, the ordering is
+case-sensitive and not accent-friendly (see examples below).
 
 .. rubric:: Examples
 
@@ -28,6 +30,14 @@ Use this rule to enforce alphabetical ordering of keys in mappings.
       key 2: val
       key 3: value
     - {a: 1, b: 2, c: 3}
+    - T-shirt: 1
+      T-shirts: 2
+      t-shirt: 3
+      t-shirts: 4
+    - hair: true
+      hais: true
+      haïr: true
+      haïssable: true
 
    the following code snippet would **FAIL**:
    ::
@@ -39,6 +49,20 @@ Use this rule to enforce alphabetical ordering of keys in mappings.
    ::
 
     - {b: 1, a: 2}
+
+   the following code snippet would **FAIL**:
+   ::
+
+    - T-shirt: 1
+      t-shirt: 2
+      T-shirts: 3
+      t-shirts: 4
+
+   the following code snippet would **FAIL**:
+   ::
+
+    - haïr: true
+      hais: true
 """
 
 import yaml