Split test_baseconverter.py::test_310_union_field_roundtrip into two to make it less flaky (#687)

* Split `test_baseconverter.py::test_310_union_field_roundtrip` into two to make it less flaky

* Fix Justfile to correctly use Pypy 3.10

Author: Tinche

Justfile

@@ -1,8 +1,9 @@
 python := ""
 covcleanup := "true"
 
-sync:
-    uv sync {{ if python != '' { '-p ' + python } else { '' } }} --all-groups --all-extras
+# Sync the environment, to a particular version if provided. The `python` variable takes precedence over the argument.
+sync version="":
+    uv sync {{ if python != '' { '-p ' + python } else if version != '' { '-p ' + version } else  { '' } }} --all-groups --all-extras
 
 lint:
 	uv run -p python3.13 --group lint ruff check src/ tests bench
@@ -13,8 +14,8 @@ test *args="-x --ff -n auto tests":
 
 testall:
     just python=python3.9 test
-    just python=pypy3.9 test
     just python=python3.10 test
+    just python=pypy3.10 test
     just python=python3.11 test
     just python=python3.12 test
     just python=python3.13 test
@@ -28,10 +29,10 @@ cov *args="-x --ff -n auto tests":
 covall:
     just python=python3.9 covcleanup=false cov
     just python=python3.10 covcleanup=false cov
+    just python=pypy3.10 covcleanup=false cov
     just python=python3.11 covcleanup=false cov
     just python=python3.12 covcleanup=false cov
     just python=python3.13 covcleanup=false cov
-    just python=pypy3.10 covcleanup=false cov
     uv run coverage combine
     uv run coverage report
     @rm .coverage*

tests/test_baseconverter.py

@@ -141,24 +141,53 @@ def handler(obj, _):
 
 
 @pytest.mark.skipif(not is_py310_plus, reason="3.10+ union syntax")
-@settings(suppress_health_check=[HealthCheck.too_slow])
 @given(
     simple_typed_classes(
         defaults="never", newtypes=False, allow_nan=False, min_attrs=1
     ),
     simple_typed_classes(
         defaults="never", newtypes=False, allow_nan=False, min_attrs=1
     ),
-    unstructure_strats,
 )
-def test_310_union_field_roundtrip(cl_and_vals_a, cl_and_vals_b, strat):
+def test_310_union_field_roundtrip_dict(cl_and_vals_a, cl_and_vals_b):
     """
     Classes with union fields can be unstructured and structured.
     """
-    converter = BaseConverter(unstruct_strat=strat)
+    converter = BaseConverter()
+    cl_a, vals_a, kwargs_a = cl_and_vals_a
+    cl_b, _, _ = cl_and_vals_b
+    a_field_names = {a.name for a in fields(cl_a)}
+    b_field_names = {a.name for a in fields(cl_b)}
+
+    common_names = a_field_names & b_field_names
+    assume(len(a_field_names) > len(common_names))
+
+    @define
+    class C:
+        a: cl_a | cl_b
+
+    inst = C(a=cl_a(*vals_a, **kwargs_a))
+
+    assert inst == converter.structure(converter.unstructure(inst), C)
+
+
+@pytest.mark.skipif(not is_py310_plus, reason="3.10+ union syntax")
+@given(
+    simple_typed_classes(
+        defaults="never", newtypes=False, allow_nan=False, min_attrs=2, kw_only="never"
+    ),
+    simple_typed_classes(
+        defaults="never", newtypes=False, allow_nan=False, min_attrs=1
+    ),
+)
+def test_310_union_field_roundtrip_tuple(cl_and_vals_a, cl_and_vals_b):
+    """
+    Classes with union fields can be unstructured and structured.
+    """
+    converter = BaseConverter(unstruct_strat=UnstructureStrategy.AS_TUPLE)
     cl_a, vals_a, kwargs_a = cl_and_vals_a
     cl_b, _, _ = cl_and_vals_b
-    assume(strat is UnstructureStrategy.AS_DICT or not kwargs_a)
+    assert not kwargs_a
     a_field_names = {a.name for a in fields(cl_a)}
     b_field_names = {a.name for a in fields(cl_b)}
 
@@ -171,18 +200,15 @@ class C:
 
     inst = C(a=cl_a(*vals_a, **kwargs_a))
 
-    if strat is UnstructureStrategy.AS_DICT:
-        assert inst == converter.structure(converter.unstructure(inst), C)
-    else:
-        # Our disambiguation functions only support dictionaries for now.
-        with pytest.raises(StructureHandlerNotFoundError):
-            converter.structure(converter.unstructure(inst), C)
+    # Our disambiguation functions only support dictionaries for now.
+    with pytest.raises(StructureHandlerNotFoundError):
+        converter.structure(converter.unstructure(inst), C)
 
-        def handler(obj, _):
-            return converter.structure(obj, cl_a)
+    def handler(obj, _):
+        return converter.structure(obj, cl_a)
 
-        converter.register_structure_hook(cl_a | cl_b, handler)
-        assert inst == converter.structure(converter.unstructure(inst), C)
+    converter.register_structure_hook(cl_a | cl_b, handler)
+    assert inst == converter.structure(converter.unstructure(inst), C)
 
 
 @given(simple_typed_classes(defaults="never", newtypes=False, allow_nan=False))