Refactor json_test's TEST_OBJECTS value into test data files (#2527)

This spreads out the gigantic list a bit, but mainly it allows us a format for adding backwards compatibility tests (where the repr file contains the intended result, instead of the object that initially produced the JSON).

The test files were generated by iterating over the test object and using cirq.to_json and repr.

Fixes #2425

This is maybe the third time I find myself refactoring this code. I wonder what the next one will be?

cirq/_compat.py

@@ -63,6 +63,24 @@ def proper_repr(value: Any) -> str:
     return repr(value)
 
 
+def proper_eq(a: Any, b: Any) -> bool:
+    """Compares objects for equality, working around __eq__ not always working.
+
+    For example, in numpy a == b broadcasts and returns an array instead of
+    doing what np.array_equal(a, b) does. This method uses np.array_equal(a, b)
+    when dealing with numpy arrays.
+    """
+    if type(a) == type(b):
+        if isinstance(a, np.ndarray):
+            return np.array_equal(a, b)
+        if isinstance(a, (pd.DataFrame, pd.Index, pd.MultiIndex)):
+            return a.equals(b)
+        if isinstance(a, (tuple, list)):
+            return len(a) == len(b) and all(
+                proper_eq(x, y) for x, y in zip(a, b))
+    return a == b
+
+
 def deprecated(*, deadline: str, fix: str, func_name: Optional[str] = None
               ) -> Callable[[Callable], Callable]:
     """Marks a function as deprecated.

cirq/_compat_test.py

@@ -19,7 +19,12 @@
 import pandas as pd
 import sympy
 
-from cirq._compat import proper_repr, deprecated, deprecated_parameter
+from cirq._compat import (
+    proper_repr,
+    deprecated,
+    deprecated_parameter,
+    proper_eq,
+)
 
 
 def test_proper_repr():
@@ -56,6 +61,20 @@ def test_proper_repr_data_frame():
     pd.testing.assert_frame_equal(df2, df)
 
 
+def test_proper_eq():
+    assert proper_eq(1, 1)
+    assert not proper_eq(1, 2)
+
+    assert proper_eq(np.array([1, 2, 3]), np.array([1, 2, 3]))
+    assert not proper_eq(np.array([1, 2, 3]), np.array([1, 2, 3, 4]))
+    assert not proper_eq(np.array([1, 2, 3]), np.array([[1, 2, 3]]))
+    assert not proper_eq(np.array([1, 2, 3]), np.array([1, 4, 3]))
+
+    assert proper_eq(pd.Index([1, 2, 3]), pd.Index([1, 2, 3]))
+    assert not proper_eq(pd.Index([1, 2, 3]), pd.Index([1, 2, 3, 4]))
+    assert not proper_eq(pd.Index([1, 2, 3]), pd.Index([1, 4, 3]))
+
+
 def test_deprecated():
 
     @deprecated(deadline='vNever', fix='Roll some dice.', func_name='test_func')

cirq/google/devices/known_devices.py

@@ -14,6 +14,7 @@
 
 from typing import Dict, Optional, Iterable, List, Set, Tuple
 
+from cirq import value
 from cirq._doc import document
 from cirq.devices import GridQubit
 from cirq.google import gate_sets, serializable_gate_set
@@ -172,14 +173,18 @@ def __init__(self, constant: str, **kwargs) -> None:
     def __repr__(self):
         return self._repr
 
+    @classmethod
+    def _from_json_dict_(cls, constant: str, **kwargs):
+        if constant == Foxtail._repr:
+            return Foxtail
+        if constant == Bristlecone._repr:
+            return Bristlecone
+        raise ValueError(f'Unrecognized xmon device name: {constant!r}')
+
     def _json_dict_(self):
         return {
             'cirq_type': self.__class__.__name__,
             'constant': self._repr,
-            'measurement_duration': self._measurement_duration,
-            'exp_w_duration': self._exp_w_duration,
-            'exp_11_duration': self._exp_z_duration,
-            'qubits': sorted(self.qubits)
         }
 
 

cirq/google/devices/known_devices_test.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import numpy as np
+import pytest
 
 import cirq
 import cirq.google as cg
@@ -377,21 +378,17 @@ def test_json_dict():
     assert cg.Foxtail._json_dict_() == {
         'cirq_type': '_NamedConstantXmonDevice',
         'constant': 'cirq.google.Foxtail',
-        'measurement_duration': cirq.Duration(nanos=4000),
-        'exp_w_duration': cirq.Duration(nanos=20),
-        'exp_11_duration': cirq.Duration(nanos=50),
-        'qubits': sorted(cirq.google.Foxtail.qubits)
     }
 
     assert cirq.google.Bristlecone._json_dict_() == {
         'cirq_type': '_NamedConstantXmonDevice',
         'constant': 'cirq.google.Bristlecone',
-        'measurement_duration': cirq.Duration(nanos=4000),
-        'exp_w_duration': cirq.Duration(nanos=20),
-        'exp_11_duration': cirq.Duration(nanos=50),
-        'qubits': sorted(cirq.google.Bristlecone.qubits)
     }
 
+    from cirq.google.devices.known_devices import _NamedConstantXmonDevice
+    with pytest.raises(ValueError, match='xmon device name'):
+        _NamedConstantXmonDevice._from_json_dict_('the_unknown_fiddler')
+
 
 def test_sycamore_device():
     q0 = cirq.GridQubit(5, 4)

cirq/protocols/json.py

@@ -317,7 +317,10 @@ def _cirq_object_hook(d, resolvers: List[Callable[[str], Union[None, Type]]]):
 
 # pylint: disable=function-redefined
 @overload
-def to_json(obj: Any, file_or_fn: Union[IO, str], *, indent=2,
+def to_json(obj: Any,
+            file_or_fn: Union[IO, pathlib.Path, str],
+            *,
+            indent=2,
             cls=CirqEncoder) -> None:
     pass