Add more functionality and tests to NameGenerator.

2 files changed, 39 insertions, 4 deletions

diff --git a/genbackupdatalib/names.py b/genbackupdatalib/names.py
index 1ce0c20..8cca24c 100644
--- a/genbackupdatalib/names.py
+++ b/genbackupdatalib/names.py
@@ -14,12 +14,23 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 
+import os
+
+
 class NameGenerator(object):
 
     '''Generate names for new output files.'''
     
     def __init__(self, dirname):
         self.dirname = dirname
-
+        self.counter = 0
+        
+    def _next_candidate_name(self):
+        self.counter += 1
+        return os.path.join(self.dirname, 'file%d' % self.counter)
+        
     def new(self):
-        return 'foo'
+        while True:
+            name = self._next_candidate_name()
+            if not os.path.exists(name):
+                return name
diff --git a/genbackupdatalib/names_tests.py b/genbackupdatalib/names_tests.py
index 7590921..55cdfd7 100644
--- a/genbackupdatalib/names_tests.py
+++ b/genbackupdatalib/names_tests.py
@@ -31,7 +31,31 @@ class NameGeneratorTests(unittest.TestCase):
     def tearDown(self):
         shutil.rmtree(self.tempdir)
 
-    def test_generates_name_that_does_not_exist(self):
+    def test_generates_name_that_is_inside_target_directory(self):
         name = self.names.new()
-        self.assertFalse(os.path.exists(name))
+        self.assert_(name.startswith(self.tempdir + os.sep))
+
+    def test_generates_different_names_every_time(self):
+        names = set(self.names.new() for i in range(10))
+        self.assertEqual(len(names), 10)
+
+    def test_generates_names_that_do_not_exist(self):
+        for i in range(10):
+            name = self.names.new()
+            self.assertFalse(os.path.exists(name))
+
+    def test_generates_the_same_sequence_with_every_instance(self):
+        n = 10
+        first = [self.names.new() for i in range(n)]
+        names2 = genbackupdatalib.NameGenerator(self.tempdir)
+        second = [names2.new() for i in range(n)]
+        self.assertEqual(first, second)
+
+    def test_does_not_generate_names_of_existing_files(self):
+        name = self.names.new()
+        file(name, 'w').close()
+        names2 = genbackupdatalib.NameGenerator(self.tempdir)
+        name2 = names2.new()
+        self.assertNotEqual(name, name2)
+        self.assertFalse(os.path.exists(name2))