Fix #123, new installations were not initializing database properly.

Also added unit test coverage to check database initialization, saving, and
loading.  Unit tests also revealed that migration code was not working properly
(starts database from scratch instead of copying existing entries over).

tests/runtests.py

@@ -6,10 +6,23 @@
 
 from __future__ import division
 import autojump
+import contextlib
+import random
 import os
+import shutil
+import sys
 import tempfile
 import unittest
 
+@contextlib.contextmanager
+def no_stderr():
+    savestderr = sys.stderr
+    class DevNull(object):
+        def write(self, _): pass
+    sys.stderr = DevNull()
+    yield
+    sys.stderr = savestderr
+
 # test suite
 class TestAutojump(unittest.TestCase):
 
@@ -18,6 +31,8 @@ class TestAutojump(unittest.TestCase):
         self.fd, self.fname = tempfile.mkstemp()
         self.db = autojump.Database(self.fname)
 
+        random.seed()
+
     def tearDown(self):
         os.remove(self.fname)
         if os.path.isfile(self.fname + ".bak"):
@@ -42,26 +57,86 @@ class TestAutojump(unittest.TestCase):
         self.db.decay()
         self.assertTrue(self.db.get_weight('/1') < 10)
 
-    def test_db_load_empty(self):
-        pass
-
-    def test_db_load_backup(self):
-        pass
-
-    def test_db_load_migrate(self):
-        pass
-
     def test_db_load_existing(self):
         self.db = autojump.Database('tests/database.txt')
         self.assertTrue(len(self.db) > 0)
 
+    def test_db_load_empty(self):
+        # setup
+        _, fname = tempfile.mkstemp()
+        db = autojump.Database(fname)
+
+        try:
+            # test
+            self.assertEquals(len(self.db), 0)
+        finally:
+            # teardown
+            os.remove(fname)
+
+    def test_db_load_backup(self):
+        # setup
+        fname = '/tmp/autojump_test_db_load_backup_' + str(random.randint(0,32678))
+        db = autojump.Database(fname)
+        db.add('/1')
+        os.rename(fname, fname + '.bak')
+
+        try:
+            # test
+            with no_stderr():
+                db = autojump.Database(fname)
+            self.assertTrue(len(db.data) > 0)
+            self.assertTrue(os.path.isfile(fname))
+        finally:
+            # teardown
+            os.remove(fname)
+            os.remove(fname + '.bak')
+
+    def test_db_load_migrate(self):
+        ORIG_CONFIG_DIR = autojump.CONFIG_DIR
+        try:
+            # setup
+            CONFIG_DIR = '/tmp/autojump_test_db_load_migrate_' + str(random.randint(0,32678))
+            os.mkdir(CONFIG_DIR)
+            autojump.CONFIG_DIR = CONFIG_DIR
+            fname = CONFIG_DIR + '/autojump_py'
+            db = autojump.Database(fname)
+            db.add('/1')
+            shutil.copy(fname, fname + '.bak')
+            db.add('/2')
+
+            # test
+            missing_fname = '/tmp/autojump_test_db_load_missing_' + str(random.randint(0,32678)) + '.txt'
+            db = autojump.Database(missing_fname)
+
+            db.add('/3')
+            self.assertEquals(len(db.data), 3)
+
+        finally:
+            # teardown
+            shutil.rmtree(CONFIG_DIR)
+            os.remove(missing_fname)
+            os.remove(missing_fname + '.bak')
+
+            autojump.CONFIG_DIR = ORIG_CONFIG_DIR
+
     def test_db_purge(self):
         self.db.add('/1')
         self.db.purge()
         self.assertEquals(len(self.db), 0)
 
     def test_db_save(self):
-        pass
+        # setup
+        fname = '/tmp/autojump_test_db_save_' + str(random.randint(0,32678)) + '.txt'
+        db = autojump.Database(fname)
+
+        try:
+            # test
+            db.save()
+            self.assertTrue(os.path.isfile(fname))
+        finally:
+            # teardown
+            os.remove(fname)
+            os.remove(fname + '.bak')
 
     def test_db_trim(self):
         self.db.add('/1')