Issue #19361: JSON decoder now raises JSONDecodeError instead of ValueError.

4 files changed, 50 insertions, 23 deletions

diff --git a/Lib/test/test_json/__init__.py b/Lib/test/test_json/__init__.py
index 2cf1032..0807e6f 100644
--- a/Lib/test/test_json/__init__.py
+++ b/Lib/test/test_json/__init__.py
@@ -9,12 +9,15 @@ from test import support
 # import json with and without accelerations
 cjson = support.import_fresh_module('json', fresh=['_json'])
 pyjson = support.import_fresh_module('json', blocked=['_json'])
+# JSONDecodeError is cached inside the _json module
+cjson.JSONDecodeError = cjson.decoder.JSONDecodeError = json.JSONDecodeError
 
 # create two base classes that will be used by the other tests
 class PyTest(unittest.TestCase):
     json = pyjson
     loads = staticmethod(pyjson.loads)
     dumps = staticmethod(pyjson.dumps)
+    JSONDecodeError = staticmethod(pyjson.JSONDecodeError)
 
 @unittest.skipUnless(cjson, 'requires _json')
 class CTest(unittest.TestCase):
@@ -22,6 +25,7 @@ class CTest(unittest.TestCase):
         json = cjson
         loads = staticmethod(cjson.loads)
         dumps = staticmethod(cjson.dumps)
+        JSONDecodeError = staticmethod(cjson.JSONDecodeError)
 
 # test PyTest and CTest checking if the functions come from the right module
 class TestPyTest(PyTest):
diff --git a/Lib/test/test_json/test_decode.py b/Lib/test/test_json/test_decode.py
index 591b2e2..cc83b45 100644
--- a/Lib/test/test_json/test_decode.py
+++ b/Lib/test/test_json/test_decode.py
@@ -63,12 +63,12 @@ class TestDecode:
     def test_extra_data(self):
         s = '[1, 2, 3]5'
         msg = 'Extra data'
-        self.assertRaisesRegex(ValueError, msg, self.loads, s)
+        self.assertRaisesRegex(self.JSONDecodeError, msg, self.loads, s)
 
     def test_invalid_escape(self):
         s = '["abc\\y"]'
         msg = 'escape'
-        self.assertRaisesRegex(ValueError, msg, self.loads, s)
+        self.assertRaisesRegex(self.JSONDecodeError, msg, self.loads, s)
 
     def test_invalid_input_type(self):
         msg = 'the JSON object must be str'
@@ -80,10 +80,10 @@ class TestDecode:
     def test_string_with_utf8_bom(self):
         # see #18958
         bom_json = "[1,2,3]".encode('utf-8-sig').decode('utf-8')
-        with self.assertRaises(ValueError) as cm:
+        with self.assertRaises(self.JSONDecodeError) as cm:
             self.loads(bom_json)
         self.assertIn('BOM', str(cm.exception))
-        with self.assertRaises(ValueError) as cm:
+        with self.assertRaises(self.JSONDecodeError) as cm:
             self.json.load(StringIO(bom_json))
         self.assertIn('BOM', str(cm.exception))
         # make sure that the BOM is not detected in the middle of a string
diff --git a/Lib/test/test_json/test_fail.py b/Lib/test/test_json/test_fail.py
index 7caafdb..95ff5b8 100644
--- a/Lib/test/test_json/test_fail.py
+++ b/Lib/test/test_json/test_fail.py
@@ -87,7 +87,7 @@ class TestFail:
                 continue
             try:
                 self.loads(doc)
-            except ValueError:
+            except self.JSONDecodeError:
                 pass
             else:
                 self.fail("Expected failure for fail{0}.json: {1!r}".format(idx, doc))
@@ -124,10 +124,16 @@ class TestFail:
             ('"spam', 'Unterminated string starting at', 0),
         ]
         for data, msg, idx in test_cases:
-            self.assertRaisesRegex(ValueError,
-                r'^{0}: line 1 column {1} \(char {2}\)'.format(
-                    re.escape(msg), idx + 1, idx),
-                self.loads, data)
+            with self.assertRaises(self.JSONDecodeError) as cm:
+                self.loads(data)
+            err = cm.exception
+            self.assertEqual(err.msg, msg)
+            self.assertEqual(err.pos, idx)
+            self.assertEqual(err.lineno, 1)
+            self.assertEqual(err.colno, idx + 1)
+            self.assertEqual(str(err),
+                             '%s: line 1 column %d (char %d)' %
+                             (msg, idx + 1, idx))
 
     def test_unexpected_data(self):
         test_cases = [
@@ -154,10 +160,16 @@ class TestFail:
             ('{"spam":42,}', 'Expecting property name enclosed in double quotes', 11),
         ]
         for data, msg, idx in test_cases:
-            self.assertRaisesRegex(ValueError,
-                r'^{0}: line 1 column {1} \(char {2}\)'.format(
-                    re.escape(msg), idx + 1, idx),
-                self.loads, data)
+            with self.assertRaises(self.JSONDecodeError) as cm:
+                self.loads(data)
+            err = cm.exception
+            self.assertEqual(err.msg, msg)
+            self.assertEqual(err.pos, idx)
+            self.assertEqual(err.lineno, 1)
+            self.assertEqual(err.colno, idx + 1)
+            self.assertEqual(str(err),
+                             '%s: line 1 column %d (char %d)' %
+                             (msg, idx + 1, idx))
 
     def test_extra_data(self):
         test_cases = [
@@ -171,11 +183,16 @@ class TestFail:
             ('"spam",42', 'Extra data', 6),
         ]
         for data, msg, idx in test_cases:
-            self.assertRaisesRegex(ValueError,
-                r'^{0}: line 1 column {1} - line 1 column {2}'
-                r' \(char {3} - {4}\)'.format(
-                    re.escape(msg), idx + 1, len(data) + 1, idx, len(data)),
-                self.loads, data)
+            with self.assertRaises(self.JSONDecodeError) as cm:
+                self.loads(data)
+            err = cm.exception
+            self.assertEqual(err.msg, msg)
+            self.assertEqual(err.pos, idx)
+            self.assertEqual(err.lineno, 1)
+            self.assertEqual(err.colno, idx + 1)
+            self.assertEqual(str(err),
+                             '%s: line 1 column %d (char %d)' %
+                             (msg, idx + 1, idx))
 
     def test_linecol(self):
         test_cases = [
@@ -185,10 +202,16 @@ class TestFail:
             ('\n  \n\n     !', 4, 6, 10),
         ]
         for data, line, col, idx in test_cases:
-            self.assertRaisesRegex(ValueError,
-                r'^Expecting value: line {0} column {1}'
-                r' \(char {2}\)$'.format(line, col, idx),
-                self.loads, data)
+            with self.assertRaises(self.JSONDecodeError) as cm:
+                self.loads(data)
+            err = cm.exception
+            self.assertEqual(err.msg, 'Expecting value')
+            self.assertEqual(err.pos, idx)
+            self.assertEqual(err.lineno, line)
+            self.assertEqual(err.colno, col)
+            self.assertEqual(str(err),
+                             'Expecting value: line %s column %d (char %d)' %
+                             (line, col, idx))
 
 class TestPyFail(TestFail, PyTest): pass
 class TestCFail(TestFail, CTest): pass
diff --git a/Lib/test/test_json/test_scanstring.py b/Lib/test/test_json/test_scanstring.py
index 07f4358..2d3ee8a 100644
--- a/Lib/test/test_json/test_scanstring.py
+++ b/Lib/test/test_json/test_scanstring.py
@@ -129,7 +129,7 @@ class TestScanstring:
             '"\\ud834\\u0X20"',
         ]
         for s in bad_escapes:
-            with self.assertRaises(ValueError, msg=s):
+            with self.assertRaises(self.JSONDecodeError, msg=s):
                 scanstring(s, 1, True)
 
     def test_overflow(self):