Add failing test for SyntaxError display

IPython/core/tests/test_ultratb.py

@@ -108,8 +108,33 b' class IndentationErrorTest(unittest.TestCase):'
                 with tt.AssertPrints("zoon()", suppress=False):
                     ip.magic('run %s' % fname)
 
+se_file_1 = """1
+2
+7/
+"""
+
+se_file_2 = """7/
+"""
+
 class SyntaxErrorTest(unittest.TestCase):
     def test_syntaxerror_without_lineno(self):
         with tt.AssertNotPrints("TypeError"):
             with tt.AssertPrints("line unknown"):
                 ip.run_cell("raise SyntaxError()")
+
+    def test_changing_py_file(self):
+        with TemporaryDirectory() as td:
+            fname = os.path.join(td, "foo.py")
+            with open(fname, 'w') as f:
+                f.write(se_file_1)
+
+            with tt.AssertPrints(["7/", "SyntaxError"]):
+                ip.magic("run " + fname)
+
+            # Modify the file
+            with open(fname, 'w') as f:
+                f.write(se_file_2)
+
+            # The SyntaxError should point to the correct line
+            with tt.AssertPrints(["7/", "SyntaxError"]):
+                ip.magic("run " + fname)

IPython/testing/tools.py

@@ -346,6 +346,8 b' class AssertPrints(object):'
     """
     def __init__(self, s, channel='stdout', suppress=True):
         self.s = s
+        if isinstance(self.s, str):
+            self.s = [self.s]
         self.channel = channel
         self.suppress = suppress
     
@@ -359,7 +361,8 b' class AssertPrints(object):'
         self.tee.flush()
         setattr(sys, self.channel, self.orig_stream)
         printed = self.buffer.getvalue()
-        assert self.s in printed, notprinted_msg.format(self.s, self.channel, printed)
+        for s in self.s:
+            assert s in printed, notprinted_msg.format(s, self.channel, printed)
         return False
 
 printed_msg = """Found {0!r} in printed output (on {1}):
@@ -376,7 +379,8 b' class AssertNotPrints(AssertPrints):'
         self.tee.flush()
         setattr(sys, self.channel, self.orig_stream)
         printed = self.buffer.getvalue()
-        assert self.s not in printed, printed_msg.format(self.s, self.channel, printed)
+        for s in self.s:
+            assert s not in printed, printed_msg.format(s, self.channel, printed)
         return False
 
 @contextmanager