Remove @cirq.testing.only_test_in_python3 (quantumlib#1579)

Part of: quantumlib#1372

Author: Victory Omole

CONTRIBUTING.md

@@ -99,11 +99,5 @@ When pylint produces a false positive, it can be squashed with annotations like
 Code should have [type annotations](https://www.python.org/dev/peps/pep-0484/).
 We use [mypy](http://mypy-lang.org/) to check that type annotations are correct.
 When type checking produces a false positive, it can be ignored with annotations like `# type: ignore`.
-- **Python 2 Convertibility**.
-Code must avoid constructs which fail to translate to python 2.
-Cirq is written in python 3, but we use [3to2](https://pypi.org/project/3to2/) (and some custom tooling) to automatically translate the code into runnable python 2 code.
-This translation step is not perfect.
-For example, `max([], default=2)` fails to translate.
-We check that the translation worked by testing the translated code against the translated tests.
-Cirq has several utilities to help the translation process along, such as the `@cirq.testing.only_test_in_python3` decorator for tests that check functionality specific to python 3.
+
 

cirq/circuits/circuit_dag_test.py

@@ -43,7 +43,7 @@ def test_wrapper_cmp():
     assert u1 >= u0
 
 
-@cirq.testing.only_test_in_python3
+
 def test_wrapper_cmp_failure():
     with pytest.raises(TypeError):
         _ = object() < cirq.Unique(1)

cirq/circuits/circuit_test.py

@@ -221,7 +221,7 @@ def test_bool():
     assert Circuit.from_ops(cirq.X(cirq.NamedQubit('a')))
 
 
-@cirq.testing.only_test_in_python3
+
 def test_repr():
     assert repr(cirq.Circuit()) == 'cirq.Circuit()'
 
@@ -325,7 +325,7 @@ def test_empty_moments():
         use_unicode_characters=True,
         transpose=True)
 
-     # 2-qubit ascii-only test
+    # 2-qubit ascii-only test
     cirq.testing.assert_has_diagram(circuit, """
 a: ---@---@-------@---
       |   |       |
@@ -360,7 +360,7 @@ def test_symbol_addition_in_gate_exponent():
 
 
     cirq.testing.assert_has_diagram(circuit,
-"""
+                                    """
 a
 │
 X^0.5
@@ -369,22 +369,22 @@ def test_symbol_addition_in_gate_exponent():
 │
 """,
                                     use_unicode_characters=True,
-     transpose=True)
+                                    transpose=True)
 
     cirq.testing.assert_has_diagram(circuit,
                                     'a: ---X^0.5---Y^(a + b)---',
                                     use_unicode_characters=False)
 
     cirq.testing.assert_has_diagram(circuit,
-"""
+                                    """
 a
 |
 X^0.5
 |
 Y^(a + b)
 |
 
-""",
+ """,
                                     use_unicode_characters=False,
                                     transpose=True)
 
@@ -2649,8 +2649,7 @@ def test_to_qasm():
         cirq.X(q0),
     )
     assert circuit.to_qasm() == cirq.qasm(circuit)
-    assert (circuit.to_qasm() ==
-"""// Generated from Cirq v{}
+    assert (circuit.to_qasm() == """// Generated from Cirq v{}
 
 OPENQASM 2.0;
 include "qelib1.inc";
@@ -2673,8 +2672,7 @@ def test_save_qasm():
         circuit.save_qasm(file_path)
         with open(file_path, 'r') as f:
             file_content = f.read()
-    assert (file_content ==
-"""// Generated from Cirq v{}
+    assert (file_content == """// Generated from Cirq v{}
 
 OPENQASM 2.0;
 include "qelib1.inc";

cirq/google/engine/engine_test.py

@@ -71,7 +71,7 @@
 }
 
 
-@cirq.testing.only_test_in_python3
+
 def test_repr():
     v = cirq.google.JobConfig(project_id='my-project-id',
                               program_id='my-program-id',
@@ -476,7 +476,7 @@ def test_implied_job_config_gcs_prefix(build):
     assert eng_with.implied_job_config(config).gcs_prefix == 'gs://better/'
 
 
-@cirq.testing.only_test_in_python3  # uses re.fullmatch
+# uses re.fullmatch
 @mock.patch.object(discovery, 'build')
 def test_implied_job_config(build):
     eng = cg.Engine(api_key="key")

cirq/google/xmon_device_test.py

@@ -79,7 +79,7 @@ def test_init_timedelta():
     assert d.duration_of(cirq.CZ(q00, q01)) == 3 * microsecond
 
 
-@cirq.testing.only_test_in_python3
+
 def test_repr():
     d = square_device(2, 2, holes=[])
 

cirq/ion/ion_device_test.py

@@ -89,7 +89,7 @@ def test_decomposition():
             """, use_unicode_characters=True)
 
 
-@cirq.testing.only_test_in_python3
+
 def test_repr():
     d = ion_device(3)
 

cirq/line/line_qubit_test.py

@@ -14,7 +14,7 @@
 
 import pytest
 
-from cirq.testing import EqualsTester, only_test_in_python3
+from cirq.testing import EqualsTester
 from cirq import LineQubit
 
 
@@ -49,7 +49,6 @@ def test_cmp():
     assert LineQubit(1) >= LineQubit(0)
 
 
-@only_test_in_python3
 def test_cmp_failure():
     with pytest.raises(TypeError):
         _ = 0 < LineQubit(1)

cirq/ops/named_qubit_test.py

@@ -23,7 +23,7 @@ def test_named_qubit_str():
 
 
 # Python 2 gives a different repr due to unicode strings being prefixed with u.
-@cirq.testing.only_test_in_python3
+
 def test_named_qubit_repr():
     q = cirq.NamedQubit('a')
     assert repr(q) == "cirq.NamedQubit('a')"

cirq/ops/pauli_gates_test.py

@@ -122,7 +122,7 @@ def test_gt():
     assert not cirq.Z > cirq.Z
 
 
-@cirq.testing.only_test_in_python3
+
 def test_gt_other_type():
     with pytest.raises(TypeError):
         _ = cirq.X > object()
@@ -140,7 +140,7 @@ def test_lt():
     assert not cirq.Z < cirq.Z
 
 
-@cirq.testing.only_test_in_python3
+
 def test_lt_other_type():
     with pytest.raises(TypeError):
         _ = cirq.X < object()

cirq/ops/pauli_string_phasor_test.py

@@ -431,7 +431,7 @@ def test_text_diagram():
 """)
 
 
-@cirq.testing.only_test_in_python3
+
 def test_repr():
     q0, q1, q2 = _make_qubits(3)
     cirq.testing.assert_equivalent_repr(

cirq/schedules/schedule_test.py

@@ -179,7 +179,7 @@ def test_query_overlapping_operations_exclusive():
 
 
 # In python 2, timedelta doesn't support multiplication with floats
-@cirq.testing.only_test_in_python3
+
 def test_query_timedelta():
     q = cirq.NamedQubit('q')
     zero = cirq.Timestamp(picos=0)

cirq/sim/density_matrix_simulator_test.py

@@ -465,7 +465,7 @@ def test_density_matrix_simulator_state_eq():
 
 
 # Python 2 gives a different repr due to unicode strings being prefixed with u.
-@cirq.testing.only_test_in_python3
+
 def test_density_matrix_simulator_state_repr():
     q0 = cirq.LineQubit(0)
     assert (repr(cirq.DensityMatrixSimulatorState(
@@ -503,7 +503,7 @@ def test_density_matrix_trial_result_eq():
 
 
 # Python 2 gives a different repr due to unicode strings being prefixed with u.
-@cirq.testing.only_test_in_python3
+
 def test_density_matrix_trial_result_repr():
     q0 = cirq.LineQubit(0)
     final_simulator_state = cirq.DensityMatrixSimulatorState(

cirq/sim/simulator_test.py

@@ -217,7 +217,7 @@ def test_simulation_trial_result_equality():
 
 
 # Python 2 gives a different repr due to unicode strings being prefixed with u.
-@cirq.testing.only_test_in_python3
+
 def test_simulation_trial_result_repr():
     assert repr(cirq.SimulationTrialResult(params=cirq.ParamResolver({'s': 1}),
                                            measurements={'m': np.array([[1]])},

cirq/sim/wave_function_simulator_test.py

@@ -18,7 +18,7 @@
 
 
 # Python 2 gives a different repr due to unicode strings being prefixed with u.
-@cirq.testing.only_test_in_python3
+
 def test_wave_function_trial_result_repr():
     final_simulator_state = cirq.WaveFunctionSimulatorState(
         qubit_map={cirq.NamedQubit('a'): 0}, state_vector=np.array([0, 1]))

cirq/study/trial_result_test.py

@@ -20,7 +20,7 @@
 
 
 # Python 2 gives a different repr due to unicode strings being prefixed with u.
-@cirq.testing.only_test_in_python3
+
 def test_repr():
     v = cirq.TrialResult(
         params=cirq.ParamResolver({'a': 2}),

cirq/testing/__init__.py

@@ -67,8 +67,5 @@
 from cirq.testing.random_circuit import (
     random_circuit,)
 
-from cirq.testing.only_test_in_python3 import (
-    only_test_in_python3,)
-
 from cirq.testing.sample_circuits import (
     nonoptimal_toffoli_circuit,)

cirq/testing/only_test_in_python3.py

@@ -87,7 +87,7 @@ def test_cmp():
 # In python 2, comparisons fallback to __cmp__ and don't fail.
 # But a custom __cmp__ that does fail would result in == failing.
 # So we throw up our hands and let it be.
-@cirq.testing.only_test_in_python3
+
 def test_cmp_vs_other_type():
     with pytest.raises(TypeError):
         _ = Duration() < 0

cirq/value/duration_test.py

@@ -70,7 +70,7 @@ def test_cmp():
 # In python 2, comparisons fallback to __cmp__ and don't fail.
 # But a custom __cmp__ that does fail would result in == failing.
 # So we throw up our hands and let it be.
-@cirq.testing.only_test_in_python3
+
 def test_cmp_vs_other_type():
     with pytest.raises(TypeError):
         _ = Timestamp() < Duration()

cirq/value/timestamp_test.py

@@ -252,7 +252,7 @@ class _:
     assert True  # HACK: sacrificial line for indentation bug in 3to2.
 
 
-@cirq.testing.only_test_in_python3
+
 def test_bad_manual_cls_forgot_method():
     with pytest.raises(TypeError, match='_value_equality_values_cls_'):