tests: Modify tests that print repr of an exception with 1 arg.

In Python 3.7 the behaviour of repr() of an exception with one argument
changed: it no longer prints a trailing comma in the argument list.  See
https://bugs.python.org/issue30399

This patch modifies tests that rely on this behaviour to not rely on it.
And the python34.py test is updated to include a test for this behaviour
with a .exp file.

Author: dpgeorge

tests/basics/dict1.py

@@ -27,7 +27,7 @@
 try:
     {}[0]
 except KeyError as er:
-    print('KeyError', er, repr(er), er.args)
+    print('KeyError', er, er.args)
 
 # unsupported unary op
 try:

tests/basics/exception1.py

@@ -1,7 +1,6 @@
 print(repr(IndexError()))
 print(str(IndexError()))
 
-print(repr(IndexError("foo")))
 print(str(IndexError("foo")))
 
 a = IndexError(1, "test", [100, 200])

tests/basics/generator_return.py

@@ -7,4 +7,4 @@ def gen():
 try:
     print(next(g))
 except StopIteration as e:
-    print(repr(e))
+    print(type(e), e.args)

tests/basics/python34.py

@@ -1,4 +1,4 @@
-# tests that differ when running under Python 3.4 vs 3.5/3.6
+# tests that differ when running under Python 3.4 vs 3.5/3.6/3.7
 
 try:
     exec
@@ -36,3 +36,7 @@ def test_syntax(code):
 import sys
 print(sys.version[:3])
 print(sys.version_info[0], sys.version_info[1])
+
+# from basics/exception1.py
+# in 3.7 no comma is printed if there is only 1 arg (in 3.4-3.6 one is printed)
+print(repr(IndexError("foo")))

tests/basics/python34.py.exp

@@ -11,3 +11,4 @@ SyntaxError
 SyntaxError
 3.4
 3 4
+IndexError('foo',)

tests/basics/subclass_native3.py

@@ -7,12 +7,12 @@ class MyExc(Exception):
 print(e.args)
 
 try:
-    raise MyExc("Some error")
+    raise MyExc("Some error", 1)
 except MyExc as e:
     print("Caught exception:", repr(e))
 
 try:
-    raise MyExc("Some error2")
+    raise MyExc("Some error2", 2)
 except Exception as e:
     print("Caught exception:", repr(e))
 

tests/basics/try_as_var.py

@@ -1,7 +1,7 @@
 try:
     raise ValueError(534)
 except ValueError as e:
-    print(repr(e))
+    print(type(e), e.args)
 
 # Var bound in except block is automatically deleted
 try:

tests/misc/sys_exc_info.py

@@ -9,7 +9,7 @@ def f():
     print(sys.exc_info()[0:2])
 
 try:
-    1/0
+    raise ValueError('value', 123)
 except:
     print(sys.exc_info()[0:2])
     f()