Refactor the sqlite3-related code

my2to3/tests/__init__.py

 from lib2to3.tests.test_fixers import FixerTestCase as lib2to3FixerTestCase
 import sqlite3
 
-from my2to3.trace import database, get_data, tracing_functions
+from my2to3.trace import conn, get_data, tracing_functions
 
 
 class FixerTestCase(lib2to3FixerTestCase):
@@ -10,16 +10,9 @@ class FixerTestCase(lib2to3FixerTestCase):
     super(FixerTestCase, self).setUp(fix_list, fixer_pkg, options)
 
     # Clear the database
-    # XXX: a better way probably exists.
-    # TODO:
-    # - refactor
-    # - optimize
-    conn = sqlite3.connect(database)
-    c = conn.cursor()
-    for table in c.execute("SELECT name FROM sqlite_master WHERE type='table'").fetchall():
-      c.execute("DELETE FROM %s" % table)
-    conn.commit()
-    conn.close()
+    with conn:
+      for table in conn.execute("SELECT name FROM sqlite_master WHERE type='table'").fetchall():
+        conn.execute("DELETE FROM %s" % table)
 
   def assertDataEqual(self, table, data):
     self.assertEqual(get_data(table), data)

my2to3/trace.py

@@ -4,6 +4,7 @@ from lib2to3.pgen2 import tokenize
 from lib2to3.refactor import get_fixers_from_package, RefactoringTool
 
 database = "traces.db"
+conn = sqlite3.connect(database)
 
 
 tracing_functions = []
@@ -13,28 +14,22 @@ def register_tracing_function(f):
 
 
 def create_table(table, *columns):
-  # TODO:
-  # - refactor
-  # - optimize
-  conn = sqlite3.connect(database)
-  c = conn.cursor()
+  with conn:
     v = ', '.join(columns)
-  c.execute("CREATE TABLE IF NOT EXISTS %s (%s, UNIQUE (%s))" % (table, v, v))
-  conn.commit()
-  conn.close()
+    conn.execute(
+      "CREATE TABLE IF NOT EXISTS %s (%s, UNIQUE (%s))" % (table, v, v)
+    )
 
   def insert_unique(*values):
-    conn = sqlite3.connect(database)
-    c = conn.cursor()
+    with conn:
       try:
-      c.execute('INSERT INTO %s VALUES (%s)' % (
-        table, ', '.join(['?'] * len(values))), values)
+        conn.execute(
+          'INSERT INTO %s VALUES (%s)' % (table, ', '.join('?' * len(values))),
+          values
+        )
       except sqlite3.IntegrityError as e:
         if not str(e).startswith('UNIQUE constraint failed:'):
           raise
-    else:
-      conn.commit()
-    conn.close()
   return insert_unique
 
 
@@ -45,21 +40,14 @@ def get_fixers():
 
 
 def get_data(table, columns_to_select='*', conditions={}):
-  # TODO:
-  # - refactor
-  # - optimize
-  conn = sqlite3.connect(database)
-  c = conn.cursor()
   query = "SELECT %s FROM %s" % (
     ', '.join(columns_to_select),
     table,
   )
   if conditions:
-    query += " WHERE " + ' AND '.join(k + " = " + v for k, v in conditions.items())
-  try:
-    return c.execute(query).fetchall()
-  finally:
-    conn.close()
+    query += " WHERE " + ' AND '.join(k + " = :" + k for k in conditions.keys())
+  with conn:
+    return conn.execute(query, conditions).fetchall()
 
 
 def apply_fixers(string, name):