Unittest the _count_trailing_newlines function

lib/ansible/template/__init__.py

@@ -90,6 +90,21 @@ def _preserve_backslashes(data, jinja_env):
 
     return data
 
+def _count_newlines_from_end(in_str):
+    '''
+    Counts the number of newlines at the end of a string. This is used during
+    the jinja2 templating to ensure the count matches the input, since some newlines
+    may be thrown away during the templating.
+    '''
+
+    i = len(in_str)
+    while i > 0:
+        if in_str[i-1] != '\n':
+            break
+        i -= 1
+
+    return len(in_str) - i
+
 class Templar:
     '''
     The main class for templating, with the main entry-point of template().
@@ -130,21 +145,6 @@ class Templar:
 
         self.SINGLE_VAR = re.compile(r"^%s\s*(\w*)\s*%s$" % (self.environment.variable_start_string, self.environment.variable_end_string))
 
-    def _count_newlines_from_end(self, in_str):
-        '''
-        Counts the number of newlines at the end of a string. This is used during
-        the jinja2 templating to ensure the count matches the input, since some newlines
-        may be thrown away during the templating.
-        '''
-
-        i = len(in_str)
-        while i > 0:
-            if in_str[i-1] != '\n':
-                break
-            i -= 1
-
-        return len(in_str) - i
-
     def _get_filters(self):
         '''
         Returns filter plugins, after loading and caching them if need be
@@ -318,7 +318,7 @@ class Templar:
 
         # For preserving the number of input newlines in the output (used
         # later in this method)
-        data_newlines = self._count_newlines_from_end(data)
+        data_newlines = _count_newlines_from_end(data)
 
         if fail_on_undefined is None:
             fail_on_undefined = self._fail_on_undefined_errors
@@ -389,7 +389,7 @@ class Templar:
                 # that version being present, modify our code to set that when
                 # initializing self.environment and remove a single trailing
                 # newline here if preserve_newlines is False.
-                res_newlines  = self._count_newlines_from_end(res)
+                res_newlines = _count_newlines_from_end(res)
                 if data_newlines > res_newlines:
                     res += '\n' * (data_newlines - res_newlines)
 

test/units/template/test_template_utilities.py

@@ -22,8 +22,10 @@ __metaclass__ = type
 import jinja2
 from ansible.compat.tests import unittest
 
-from ansible.template import _preserve_backslashes
+from ansible.template import _preserve_backslashes, _count_newlines_from_end
 
+# These are internal utility functions only needed for templating.  They're
+# algorithmic so good candidates for unittesting by themselves
 
 class TestBackslashEscape(unittest.TestCase):
 
@@ -83,3 +85,28 @@ class TestBackslashEscape(unittest.TestCase):
             args = test['args']
             self.assertEquals(template.render(**args), test['expectation'])
 
+class TestCountNewlines(unittest.TestCase):
+
+    def setUp(self):
+        pass
+
+    def tearDown(self):
+        pass
+
+    def test_short_string(self):
+        self.assertEquals(_count_newlines_from_end('The quick\n'), 1)
+
+    def test_one_newline(self):
+        self.assertEquals(_count_newlines_from_end('The quick brown fox jumped over the lazy dog' * 1000 + '\n'), 1)
+
+    def test_multiple_newlines(self):
+        self.assertEquals(_count_newlines_from_end('The quick brown fox jumped over the lazy dog' * 1000 + '\n\n\n'), 3)
+
+    def test_zero_newlines(self):
+        self.assertEquals(_count_newlines_from_end('The quick brown fox jumped over the lazy dog' * 1000 + '\n\n\n'), 3)
+
+    def test_all_newlines(self):
+        self.assertEquals(_count_newlines_from_end('\n' * 10), 10)
+
+    def test_mostly_newlines(self):
+        self.assertEquals(_count_newlines_from_end('The quick brown fox jumped over the lazy dog' + '\n' * 1000), 1000)