Update json field tests to account for error cases

tests/test_json_field.py

@@ -36,6 +36,43 @@ def test_json(fakedb):
     model = TestModel.get()
     assert model.some_data == data
 
-    with pytest.raises(peewee.IntegrityError):
+
-        bad = TestModel(some_data=Path("."))
+def test_errors(fakedb):
+    """Test that errors are raised as expected"""
+
+    class GoodModel(peewee.Model):
+        class Meta:
+            database = fakedb
+            # Needs to match the table name below
+            table_name = "one_table"
+
+        id = peewee.AutoField()
+        some_data = peewee_plus.JSONField()
+
+    class BadModel(peewee.Model):
+        class Meta:
+            database = fakedb
+            # Needs to match the table name above
+            table_name = "one_table"
+
+        id = peewee.AutoField()
+        some_data = peewee.TextField()
+
+    fakedb.create_tables([GoodModel])
+
+    with pytest.raises(ValueError):
+        # The usage of path here is arbitrary, it just needs to be any
+        # non-JSON serializable type
+        bad = GoodModel(some_data=Path("."))
         bad.save()
+
+    good = GoodModel(some_data={"foo": 123})
+    good.save()
+
+    # This is overwriting the ``some_data`` on the above object with garbage
+    bad = BadModel.get(good.id)
+    bad.some_data = "This{ string' is not, valid JSON;"
+    bad.save()
+
+    with pytest.raises(peewee.IntegrityError):
+        GoodModel.get(good.id)