[Error Message] Dataclasses Mismatched Type (#2650)

* Show different of types in dataclass when transforming error

Signed-off-by: Future-Outlier <eric901201@gmail.com>

* add tests for dataclass

Signed-off-by: Future-Outlier <eric901201@gmail.com>

* fix tests

Signed-off-by: Future-Outlier <eric901201@gmail.com>

---------

Signed-off-by: Future-Outlier <eric901201@gmail.com>

flytekit/core/base_task.py

@@ -636,7 +636,11 @@ def _output_to_literal_map(self, native_outputs: Dict[int, Any], ctx: FlyteConte
                 except Exception as e:
                     # only show the name of output key if it's user-defined (by default Flyte names these as "o<n>")
                     key = k if k != f"o{i}" else i
-                    msg = f"Failed to convert outputs of task '{self.name}' at position {key}:\n  {e}"
+                    msg = (
+                        f"Failed to convert outputs of task '{self.name}' at position {key}.\n"
+                        f"Failed to convert type {type(native_outputs_as_map[expected_output_names[i]])} to type {py_type}.\n"
+                        f"Error Message: {e}."
+                    )
                     logger.error(msg)
                     raise TypeError(msg) from e
                 # Now check if there is any output metadata associated with this output variable and attach it to the

tests/flytekit/unit/core/test_type_hints.py

@@ -1568,6 +1568,17 @@ def t2() -> Bar:
 
 
 def test_error_messages():
+    @dataclass
+    class DC1:
+        a: int
+        b: str
+
+    @dataclass
+    class DC2:
+        a: int
+        b: str
+        c: int
+
     @task
     def foo(a: int, b: str) -> typing.Tuple[int, str]:
         return 10, "hello"
@@ -1580,6 +1591,10 @@ def foo2(a: int, b: str) -> typing.Tuple[int, str]:
     def foo3(a: typing.Dict) -> typing.Dict:
         return a
 
+    @task
+    def foo4(input: DC1=DC1(1, 'a')) -> DC2:
+        return input  # type: ignore
+
     # pytest-xdist uses `__channelexec__` as the top-level module
     running_xdist = os.environ.get("PYTEST_XDIST_WORKER") is not None
     prefix = "__channelexec__." if running_xdist else ""
@@ -1596,9 +1611,9 @@ def foo3(a: typing.Dict) -> typing.Dict:
     with pytest.raises(
         TypeError,
         match=(
-            f"Failed to convert outputs of task '{prefix}tests.flytekit.unit.core.test_type_hints.foo2' "
-            "at position 0:\n"
-            "  Expected value of type <class 'int'> but got 'hello' of type <class 'str'>"
+            f"Failed to convert outputs of task '{prefix}tests.flytekit.unit.core.test_type_hints.foo2' at position 0.\n"
+            f"Failed to convert type <class 'str'> to type <class 'int'>.\n"
+            "Error Message: Expected value of type <class 'int'> but got 'hello' of type <class 'str'>."
         ),
     ):
         foo2(a=10, b="hello")
@@ -1610,6 +1625,15 @@ def foo3(a: typing.Dict) -> typing.Dict:
     ):
         foo3(a=[{"hello": 2}])
 
+    with pytest.raises(
+        TypeError,
+        match=(
+            f"Failed to convert outputs of task '{prefix}tests.flytekit.unit.core.test_type_hints.foo4' at position 0.\n"
+            f"Failed to convert type <class 'tests.flytekit.unit.core.test_type_hints.test_error_messages.<locals>.DC1'> to type <class 'tests.flytekit.unit.core.test_type_hints.test_error_messages.<locals>.DC2'>.\n"
+            "Error Message: 'DC1' object has no attribute 'c'."
+        ),
+    ):
+        foo4()
 
 def test_failure_node():
     @task