improve output

Author: DifferentialOrange

test/suites/test_error_ext.py

@@ -295,12 +295,22 @@ def test_tarantool_decode(self):
 
                 # Tarantool error file and line could differ even between
                 # different patches.
+                #
+                # Also, in Tarantool errors are not comparable at all.
+                #
+                # tarantool> msgpack.decode(error_str) == msgpack.decode(error_str)
+                # ---
+                # - false
+                # ...
+
                 self.assertEqual(res[0][0], case['str_type'](name))
                 self.assertEqual(res[0][2], case['str_type']('payload'))
 
-                self.assertTrue(isinstance(res[0][1], tarantool.BoxError))
-
                 err = res[0][1]
+                self.assertTrue(
+                    isinstance(err, tarantool.BoxError),
+                    f'{err} is expected to be a BoxError object')
+
                 expected_err = case['python']
                 while err is not None:
                     self.assertEqual(err.type, expected_err.type)
@@ -341,12 +351,6 @@ def test_tarantool_encode(self):
                     local tuple = box.space['test']:get('{name}')
                     assert(tuple ~= nil)
 
-                    -- Tarantool errors are not comparable at all.
-                    --
-                    -- tarantool> msgpack.decode(error_str) == msgpack.decode(error_str)
-                    -- ---
-                    -- - false
-                    -- ...
 
                     local tuple_err = tuple[2]