Modernize sqlite3 tests

Update current tests that use old pattern with assertRaises
to make them more maintainable.

Lib/sqlite3/test/hooks.py

@@ -33,19 +33,14 @@ class CollationTests(unittest.TestCase):
 
     def CheckCreateCollationNotCallable(self):
         con = sqlite.connect(":memory:")
-        try:
+        with self.assertRaises(TypeError) as cm:
             con.create_collation("X", 42)
-            self.fail("should have raised a TypeError")
-        except TypeError as e:
-            self.assertEqual(e.args[0], "parameter must be callable")
+        self.assertEqual(str(cm.exception), 'parameter must be callable')
 
     def CheckCreateCollationNotAscii(self):
         con = sqlite.connect(":memory:")
-        try:
+        with self.assertRaises(sqlite.ProgrammingError):
             con.create_collation("collä", lambda x, y: (x > y) - (x < y))
-            self.fail("should have raised a ProgrammingError")
-        except sqlite.ProgrammingError as e:
-            pass
 
     @unittest.skipIf(sqlite.sqlite_version_info < (3, 2, 1),
                      'old SQLite versions crash on this test')
@@ -70,11 +65,9 @@ class CollationTests(unittest.TestCase):
             self.fail("the expected order was not returned")
 
         con.create_collation("mycoll", None)
-        try:
+        with self.assertRaises(sqlite.OperationalError) as cm:
             result = con.execute(sql).fetchall()
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError as e:
-            self.assertEqual(e.args[0].lower(), "no such collation sequence: mycoll")
+        self.assertEqual(str(cm.exception), 'no such collation sequence: mycoll')
 
     def CheckCollationReturnsLargeInteger(self):
         def mycoll(x, y):
@@ -106,8 +99,8 @@ class CollationTests(unittest.TestCase):
         result = con.execute("""
             select x from (select 'a' as x union select 'b' as x) order by x collate mycoll
             """).fetchall()
-        if result[0][0] != 'b' or result[1][0] != 'a':
-            self.fail("wrong collation function is used")
+        self.assertEqual(result[0][0], 'b')
+        self.assertEqual(result[1][0], 'a')
 
     def CheckDeregisterCollation(self):
         """
@@ -117,12 +110,9 @@ class CollationTests(unittest.TestCase):
         con = sqlite.connect(":memory:")
         con.create_collation("mycoll", lambda x, y: (x > y) - (x < y))
         con.create_collation("mycoll", None)
-        try:
+        with self.assertRaises(sqlite.OperationalError) as cm:
             con.execute("select 'a' as x union select 'b' as x order by x collate mycoll")
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError as e:
-            if not e.args[0].startswith("no such collation sequence"):
-                self.fail("wrong OperationalError raised")
+        self.assertEqual(str(cm.exception), 'no such collation sequence: mycoll')
 
 class ProgressTests(unittest.TestCase):
     def CheckProgressHandlerUsed(self):

Lib/sqlite3/test/regression.py

@@ -170,14 +170,8 @@ class RegressionTests(unittest.TestCase):
 
         con = sqlite.connect(":memory:")
         cur = Cursor(con)
-        try:
+        with self.assertRaises(sqlite.ProgrammingError):
             cur.execute("select 4+5").fetchall()
-            self.fail("should have raised ProgrammingError")
-        except sqlite.ProgrammingError:
-            pass
-        except:
-            self.fail("should have raised ProgrammingError")
-
 
     def CheckStrSubclass(self):
         """
@@ -196,13 +190,8 @@ class RegressionTests(unittest.TestCase):
                 pass
 
         con = Connection(":memory:")
-        try:
+        with self.assertRaises(sqlite.ProgrammingError):
             cur = con.cursor()
-            self.fail("should have raised ProgrammingError")
-        except sqlite.ProgrammingError:
-            pass
-        except:
-            self.fail("should have raised ProgrammingError")
 
     def CheckCursorRegistration(self):
         """
@@ -223,13 +212,8 @@ class RegressionTests(unittest.TestCase):
         cur.executemany("insert into foo(x) values (?)", [(3,), (4,), (5,)])
         cur.execute("select x from foo")
         con.rollback()
-        try:
+        with self.assertRaises(sqlite.InterfaceError):
             cur.fetchall()
-            self.fail("should have raised InterfaceError")
-        except sqlite.InterfaceError:
-            pass
-        except:
-            self.fail("should have raised InterfaceError")
 
     def CheckAutoCommit(self):
         """

Lib/sqlite3/test/transactions.py

@@ -118,13 +118,8 @@ class TransactionTests(unittest.TestCase):
             return
         self.cur1.execute("create table test(i)")
         self.cur1.execute("insert into test(i) values (5)")
-        try:
+        with self.assertRaises(sqlite.OperationalError):
             self.cur2.execute("insert into test(i) values (5)")
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError:
-            pass
-        except:
-            self.fail("should have raised an OperationalError")
 
     def CheckLocking(self):
         """
@@ -137,13 +132,8 @@ class TransactionTests(unittest.TestCase):
             return
         self.cur1.execute("create table test(i)")
         self.cur1.execute("insert into test(i) values (5)")
-        try:
+        with self.assertRaises(sqlite.OperationalError):
             self.cur2.execute("insert into test(i) values (5)")
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError:
-            pass
-        except:
-            self.fail("should have raised an OperationalError")
         # NO self.con2.rollback() HERE!!!
         self.con1.commit()
 
@@ -159,13 +149,8 @@ class TransactionTests(unittest.TestCase):
         cur.execute("select 1 union select 2 union select 3")
 
         con.rollback()
-        try:
+        with self.assertRaises(sqlite.InterfaceError):
             cur.fetchall()
-            self.fail("InterfaceError should have been raised")
-        except sqlite.InterfaceError as e:
-            pass
-        except:
-            self.fail("InterfaceError should have been raised")
 
 class SpecialCommandTests(unittest.TestCase):
     def setUp(self):

Lib/sqlite3/test/types.py

@@ -185,24 +185,14 @@ class DeclTypesTests(unittest.TestCase):
     def CheckUnsupportedSeq(self):
         class Bar: pass
         val = Bar()
-        try:
+        with self.assertRaises(sqlite.InterfaceError):
             self.cur.execute("insert into test(f) values (?)", (val,))
-            self.fail("should have raised an InterfaceError")
-        except sqlite.InterfaceError:
-            pass
-        except:
-            self.fail("should have raised an InterfaceError")
 
     def CheckUnsupportedDict(self):
         class Bar: pass
         val = Bar()
-        try:
+        with self.assertRaises(sqlite.InterfaceError):
             self.cur.execute("insert into test(f) values (:val)", {"val": val})
-            self.fail("should have raised an InterfaceError")
-        except sqlite.InterfaceError:
-            pass
-        except:
-            self.fail("should have raised an InterfaceError")
 
     def CheckBlob(self):
         # default

Lib/sqlite3/test/userfunctions.py

@@ -162,11 +162,8 @@ class FunctionTests(unittest.TestCase):
         self.con.close()
 
     def CheckFuncErrorOnCreate(self):
-        try:
+        with self.assertRaises(sqlite.OperationalError):
             self.con.create_function("bla", -100, lambda x: 2*x)
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError:
-            pass
 
     def CheckFuncRefCount(self):
         def getfunc():
@@ -231,12 +228,10 @@ class FunctionTests(unittest.TestCase):
 
     def CheckFuncException(self):
         cur = self.con.cursor()
-        try:
+        with self.assertRaises(sqlite.OperationalError) as cm:
             cur.execute("select raiseexception()")
             cur.fetchone()
-            self.fail("should have raised OperationalError")
-        except sqlite.OperationalError as e:
-            self.assertEqual(e.args[0], 'user-defined function raised exception')
+        self.assertEqual(str(cm.exception), 'user-defined function raised exception')
 
     def CheckParamString(self):
         cur = self.con.cursor()
@@ -312,55 +307,42 @@ class AggregateTests(unittest.TestCase):
         pass
 
     def CheckAggrErrorOnCreate(self):
-        try:
+        with self.assertRaises(sqlite.OperationalError):
             self.con.create_function("bla", -100, AggrSum)
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError:
-            pass
 
     def CheckAggrNoStep(self):
         cur = self.con.cursor()
-        try:
+        with self.assertRaises(AttributeError) as cm:
             cur.execute("select nostep(t) from test")
-            self.fail("should have raised an AttributeError")
-        except AttributeError as e:
-            self.assertEqual(e.args[0], "'AggrNoStep' object has no attribute 'step'")
+        self.assertEqual(str(cm.exception), "'AggrNoStep' object has no attribute 'step'")
 
     def CheckAggrNoFinalize(self):
         cur = self.con.cursor()
-        try:
+        with self.assertRaises(sqlite.OperationalError) as cm:
             cur.execute("select nofinalize(t) from test")
             val = cur.fetchone()[0]
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError as e:
-            self.assertEqual(e.args[0], "user-defined aggregate's 'finalize' method raised error")
+        self.assertEqual(str(cm.exception), "user-defined aggregate's 'finalize' method raised error")
 
     def CheckAggrExceptionInInit(self):
         cur = self.con.cursor()
-        try:
+        with self.assertRaises(sqlite.OperationalError) as cm:
             cur.execute("select excInit(t) from test")
             val = cur.fetchone()[0]
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError as e:
-            self.assertEqual(e.args[0], "user-defined aggregate's '__init__' method raised error")
+        self.assertEqual(str(cm.exception), "user-defined aggregate's '__init__' method raised error")
 
     def CheckAggrExceptionInStep(self):
         cur = self.con.cursor()
-        try:
+        with self.assertRaises(sqlite.OperationalError) as cm:
             cur.execute("select excStep(t) from test")
             val = cur.fetchone()[0]
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError as e:
-            self.assertEqual(e.args[0], "user-defined aggregate's 'step' method raised error")
+        self.assertEqual(str(cm.exception), "user-defined aggregate's 'step' method raised error")
 
     def CheckAggrExceptionInFinalize(self):
         cur = self.con.cursor()
-        try:
+        with self.assertRaises(sqlite.OperationalError) as cm:
             cur.execute("select excFinalize(t) from test")
             val = cur.fetchone()[0]
-            self.fail("should have raised an OperationalError")
-        except sqlite.OperationalError as e:
-            self.assertEqual(e.args[0], "user-defined aggregate's 'finalize' method raised error")
+        self.assertEqual(str(cm.exception), "user-defined aggregate's 'finalize' method raised error")
 
     def CheckAggrCheckParamStr(self):
         cur = self.con.cursor()
@@ -433,22 +415,14 @@ class AuthorizerTests(unittest.TestCase):
         pass
 
     def test_table_access(self):
-        try:
+        with self.assertRaises(sqlite.DatabaseError) as cm:
             self.con.execute("select * from t2")
-        except sqlite.DatabaseError as e:
-            if not e.args[0].endswith("prohibited"):
-                self.fail("wrong exception text: %s" % e.args[0])
-            return
-        self.fail("should have raised an exception due to missing privileges")
+        self.assertIn('prohibited', str(cm.exception))
 
     def test_column_access(self):
-        try:
+        with self.assertRaises(sqlite.DatabaseError) as cm:
             self.con.execute("select c2 from t1")
-        except sqlite.DatabaseError as e:
-            if not e.args[0].endswith("prohibited"):
-                self.fail("wrong exception text: %s" % e.args[0])
-            return
-        self.fail("should have raised an exception due to missing privileges")
+        self.assertIn('prohibited', str(cm.exception))
 
 class AuthorizerRaiseExceptionTests(AuthorizerTests):
     @staticmethod