Pytest without cirq.google (#3894)

Enables testing without the existence of cirq.google. 

Namely: 
- check/pytest gets a `--cirq-only` arg, that deletes the cirq/google directory and runs pytest  - also adds a new CI job just for this reason
- this forced the removal of some remaining cirq.google references from cirq core and some was made optional (see next point)
- cirq.google references can still be made from tests but they will be skipped using `@cirq.testing.skip_if_module_not_exists(module="cirq.google")` - the examples folder, performance benchmarking are places where this is okay. In other places this is considered technical debt and we'll need to figure out how to remove those instances cleanly (probably by creating the test infra for those features that the modules can call into)

Note: this should be merged after #3888 (it is merged into this branch).

Closes #3737.

.github/workflows/ci.yml

@@ -1,6 +1,6 @@
 name: Continuous Integration
 
-on: [pull_request]
+on: [ pull_request ]
 
 jobs:
   quick_test:
@@ -100,12 +100,29 @@ jobs:
           architecture: 'x64'
       - name: Doc check
         run: check/nbformat
+  cirq-only:
+    name: Pytest (cirq-only) Ubuntu
+    runs-on: ubuntu-16.04
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v1
+        with:
+          python-version: '3.8'
+          architecture: 'x64'
+      - name: Install requirements
+        run: |
+          pip install -r requirements.txt
+          pip install -r dev_tools/conf/pip-list-dev-tools.txt
+          # TODO: move to requirements.txt after #3704
+          pip install codeowners==0.1.2 # linux only package
+      - name: Pytest check
+        run: check/pytest --cirq-only --ignore=cirq/contrib --actually-quiet
   pytest:
     name: Pytest Ubuntu
     strategy:
       matrix:
         # TODO(#3800): remove 3.6 when Colab switches to 3.7
-        python-version: ['3.6', '3.7', '3.8']
+        python-version: [ '3.6', '3.7', '3.8' ]
     runs-on: ubuntu-16.04
     steps:
       - uses: actions/checkout@v2
@@ -178,7 +195,7 @@ jobs:
     name: Pytest Windows
     strategy:
       matrix:
-        python-version: ['3.7', '3.8']
+        python-version: [ '3.7', '3.8' ]
     runs-on: windows-latest
     steps:
       - uses: actions/checkout@v2
@@ -197,7 +214,7 @@ jobs:
     name: Pytest MacOS
     strategy:
       matrix:
-        python-version: ['3.7', '3.8']
+        python-version: [ '3.7', '3.8' ]
     runs-on: macos-10.15
     steps:
       - uses: actions/checkout@v2

check/pytest

@@ -22,11 +22,21 @@ ACTUALLY_QUIET=""
 for arg in $@; do
     if [[ "${arg}" == "--actually-quiet" ]]; then
         ACTUALLY_QUIET=1
+    elif [[ "${arg}" == "--cirq-only" ]]; then
+        tmp_dir=$(mktemp -d "/tmp/cirq-pytest.XXXXXXXXXXXXXXXX")
+        cp -R ./* ${tmp_dir}/
+        cp -R ./.github ${tmp_dir}/
+        cp -R ./.git ${tmp_dir}/
+        cd ${tmp_dir}
+        rm -rf cirq/google
+        trap "{ rm -rf ${tmp_dir}; }" EXIT
     else
         PYTEST_ARGS+=("${arg}")
     fi
 done
 
+
+
 if [ -z "${ACTUALLY_QUIET}" ]; then
     pytest "${PYTEST_ARGS[@]}"
 else

cirq/__init__.py

@@ -11,6 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from logging import warning
 
 from cirq import _import
 
@@ -51,7 +52,6 @@
     interop,
     # Applications
     experiments,
-    google,
     # Extra (nothing should depend on these)
     testing,
 )
@@ -564,12 +564,17 @@
 # Unflattened sub-modules.
 
 from cirq import (
-    google,
     ionq,
     pasqal,
     testing,
 )
 
+try:
+    from cirq import google
+except ImportError as ex:
+    # coverage: ignore
+    warning("Can't import cirq.google: ", ex)
+
 
 def _register_resolver() -> None:
     """Registers the cirq module's public classes for JSON serialization."""

cirq/circuits/frozen_circuit_test.py

@@ -55,4 +55,4 @@ def test_immutable():
         c.moments = (cirq.Moment(cirq.H(q)), cirq.Moment(cirq.X(q)))
 
     with pytest.raises(AttributeError, match="can't set attribute"):
-        c.device = cirq.google.devices.Foxtail
+        c.device = cirq.UNCONSTRAINED_DEVICE

cirq/contrib/paulistring/recombine_test.py

@@ -11,10 +11,9 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
+import pytest
 
 import cirq
-
 from cirq.contrib.paulistring import (
     convert_and_separate_circuit,
     pauli_string_dag_from_circuit,
@@ -29,6 +28,7 @@ def _assert_no_multi_qubit_pauli_strings(circuit: cirq.Circuit) -> None:
 
 
 def test_move_non_clifford_into_clifford():
+    cg = pytest.importorskip("cirq.google")
     q0, q1, q2 = cirq.LineQubit.range(3)
     c_orig = cirq.testing.nonoptimal_toffoli_circuit(q0, q1, q2)
 
@@ -43,8 +43,8 @@ def test_move_non_clifford_into_clifford():
     _assert_no_multi_qubit_pauli_strings(c_recombined1)
     _assert_no_multi_qubit_pauli_strings(c_recombined2)
 
-    baseline_len = len(cirq.google.optimized_for_xmon(c_orig))
-    opt_len1 = len(cirq.google.optimized_for_xmon(c_recombined1))
-    opt_len2 = len(cirq.google.optimized_for_xmon(c_recombined2))
+    baseline_len = len(cg.optimized_for_xmon(c_orig))
+    opt_len1 = len(cg.optimized_for_xmon(c_recombined1))
+    opt_len2 = len(cg.optimized_for_xmon(c_recombined2))
     assert opt_len1 <= baseline_len
     assert opt_len2 <= baseline_len

cirq/experiments/google_v2_supremacy_circuit_test.py

@@ -45,6 +45,7 @@ def test_google_v2_supremacy_circuit():
 
 
 def test_google_v2_supremacy_bristlecone():
+    pytest.importorskip("cirq.google")
     # Check instance consistency
     c = supremacy_v2.generate_boixo_2018_supremacy_circuits_v2_bristlecone(
         n_rows=11, cz_depth=8, seed=0
@@ -71,6 +72,7 @@ def test_google_v2_supremacy_bristlecone():
 
 
 def test_n_rows_less_than_2():
+    pytest.importorskip("cirq.google")
     with pytest.raises(AssertionError):
         supremacy_v2.generate_boixo_2018_supremacy_circuits_v2_bristlecone(
             n_rows=1, cz_depth=0, seed=0

cirq/experiments/random_quantum_circuit_generation_test.py

@@ -257,6 +257,11 @@ def _cz_with_adjacent_z_rotations(
     yield cirq.Z(b) ** z_exponents[3]
 
 
+class FakeSycamoreGate(cirq.FSimGate):
+    def __init__(self):
+        super().__init__(theta=np.pi / 2, phi=np.pi / 6)
+
+
 @pytest.mark.parametrize(
     'qubits, depth, two_qubit_op_factory, pattern, '
     'single_qubit_gates, add_final_single_qubit_layer, '
@@ -278,7 +283,7 @@ def _cz_with_adjacent_z_rotations(
         (
             cirq.GridQubit.rect(4, 3),
             20,
-            lambda a, b, _: cirq.google.SYC(a, b),
+            lambda a, b, _: FakeSycamoreGate()(a, b),
             cirq.experiments.HALF_GRID_STAGGERED_PATTERN,
             (cirq.X ** 0.5, cirq.Y ** 0.5, cirq.Z ** 0.5),
             True,

cirq/google/devices/known_devices_test.py

@@ -15,7 +15,7 @@
 import pytest
 
 import cirq
-import cirq.google as cg
+import cirq.google
 import cirq.google.common_serializers as cgc
 import cirq.google.devices.known_devices as known_devices
 
@@ -301,7 +301,7 @@ def test_create_device_proto_for_irregular_grid():
 
 
 def test_multiple_gate_sets():
-    halfPiGateSet = cg.serializable_gate_set.SerializableGateSet(
+    halfPiGateSet = cirq.google.serializable_gate_set.SerializableGateSet(
         gate_set_name='half_pi_gateset',
         serializers=[*cgc.SINGLE_QUBIT_HALF_PI_SERIALIZERS, cgc.MEASUREMENT_SERIALIZER],
         deserializers=[*cgc.SINGLE_QUBIT_HALF_PI_DESERIALIZERS, cgc.MEASUREMENT_DESERIALIZER],
@@ -314,7 +314,7 @@ def test_multiple_gate_sets():
         'meas': 14_141,
     }
     test_proto = known_devices.create_device_proto_from_diagram(
-        "aa\naa", [cg.gate_sets.XMON, halfPiGateSet], durations_dict
+        "aa\naa", [cirq.google.gate_sets.XMON, halfPiGateSet], durations_dict
     )
     assert (
         str(test_proto)
@@ -457,7 +457,7 @@ def test_multiple_gate_sets():
 
 
 def test_json_dict():
-    assert cg.Foxtail._json_dict_() == {
+    assert cirq.google.Foxtail._json_dict_() == {
         'cirq_type': '_NamedConstantXmonDevice',
         'constant': 'cirq.google.Foxtail',
     }
@@ -471,7 +471,7 @@ def test_json_dict():
         known_devices._NamedConstantXmonDevice._from_json_dict_('the_unknown_fiddler')
 
 
-@pytest.mark.parametrize('device', [cg.Sycamore, cg.Sycamore23])
+@pytest.mark.parametrize('device', [cirq.google.Sycamore, cirq.google.Sycamore23])
 def test_sycamore_devices(device):
     q0 = cirq.GridQubit(5, 3)
     q1 = cirq.GridQubit(5, 4)
@@ -489,26 +489,28 @@ def test_sycamore_grid_layout():
     q1 = cirq.GridQubit(5, 6)
     syc = cirq.FSimGate(theta=np.pi / 2, phi=np.pi / 6)(q0, q1)
     sqrt_iswap = cirq.FSimGate(theta=np.pi / 4, phi=0)(q0, q1)
-    cg.Sycamore.validate_operation(syc)
-    cg.Sycamore.validate_operation(sqrt_iswap)
+    cirq.google.Sycamore.validate_operation(syc)
+    cirq.google.Sycamore.validate_operation(sqrt_iswap)
 
     with pytest.raises(ValueError):
-        cg.Sycamore23.validate_operation(syc)
+        cirq.google.Sycamore23.validate_operation(syc)
     with pytest.raises(ValueError):
-        cg.Sycamore23.validate_operation(sqrt_iswap)
+        cirq.google.Sycamore23.validate_operation(sqrt_iswap)
 
 
 def test_proto_with_waitgate():
-    wait_gateset = cg.serializable_gate_set.SerializableGateSet(
+    wait_gateset = cirq.google.serializable_gate_set.SerializableGateSet(
         gate_set_name='wait_gateset',
         serializers=[cgc.WAIT_GATE_SERIALIZER],
         deserializers=[cgc.WAIT_GATE_DESERIALIZER],
     )
-    wait_proto = cg.devices.known_devices.create_device_proto_from_diagram(
+    wait_proto = cirq.google.devices.known_devices.create_device_proto_from_diagram(
         "aa\naa",
         [wait_gateset],
     )
-    wait_device = cg.SerializableDevice.from_proto(proto=wait_proto, gate_sets=[wait_gateset])
+    wait_device = cirq.google.SerializableDevice.from_proto(
+        proto=wait_proto, gate_sets=[wait_gateset]
+    )
     q0 = cirq.GridQubit(1, 1)
     wait_op = cirq.wait(q0, nanos=25)
     wait_device.validate_operation(wait_op)
@@ -560,7 +562,7 @@ def test_proto_with_waitgate():
 
 
 def test_adding_gates_multiple_times():
-    waiting_for_godot = cg.serializable_gate_set.SerializableGateSet(
+    waiting_for_godot = cirq.google.serializable_gate_set.SerializableGateSet(
         gate_set_name='wait_gateset',
         serializers=[cgc.WAIT_GATE_SERIALIZER, cgc.WAIT_GATE_SERIALIZER, cgc.WAIT_GATE_SERIALIZER],
         deserializers=[
@@ -569,11 +571,13 @@ def test_adding_gates_multiple_times():
             cgc.WAIT_GATE_DESERIALIZER,
         ],
     )
-    wait_proto = cg.devices.known_devices.create_device_proto_from_diagram(
+    wait_proto = cirq.google.devices.known_devices.create_device_proto_from_diagram(
         "aa",
         [waiting_for_godot],
     )
-    wait_device = cg.SerializableDevice.from_proto(proto=wait_proto, gate_sets=[waiting_for_godot])
+    wait_device = cirq.google.SerializableDevice.from_proto(
+        proto=wait_proto, gate_sets=[waiting_for_godot]
+    )
     q0 = cirq.GridQubit(0, 0)
     wait_op = cirq.wait(q0, nanos=25)
     wait_device.validate_operation(wait_op)

cirq/ops/measurement_gate.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Any, Dict, Iterable, Optional, Tuple, Sequence, TYPE_CHECKING, List
+from typing import Any, Dict, Iterable, Optional, Tuple, Sequence, TYPE_CHECKING
 
 import numpy as np
 

cirq/optimizers/cphase_to_fsim_test.py

@@ -8,11 +8,16 @@
 import cirq
 
 
+class FakeSycamoreGate(cirq.FSimGate):
+    def __init__(self):
+        super().__init__(theta=np.pi / 2, phi=np.pi / 6)
+
+
 def test_parameterized_gates():
     t = sympy.Symbol('t')
     with pytest.raises(ValueError):
         cphase_gate = cirq.CZPowGate(exponent=t)
-        fsim_gate = cirq.google.SYC
+        fsim_gate = FakeSycamoreGate()
         cirq.decompose_cphase_into_two_fsim(cphase_gate, fsim_gate=fsim_gate)
 
     with pytest.raises(ValueError):
@@ -29,18 +34,19 @@ def test_parameterized_gates():
 def test_invalid_qubits():
     with pytest.raises(ValueError):
         cirq.decompose_cphase_into_two_fsim(
-            cphase_gate=cirq.CZ, fsim_gate=cirq.google.SYC, qubits=cirq.LineQubit.range(3)
+            cphase_gate=cirq.CZ, fsim_gate=FakeSycamoreGate(), qubits=cirq.LineQubit.range(3)
         )
 
 
 def test_circuit_structure():
-    ops = cirq.decompose_cphase_into_two_fsim(cirq.CZ, fsim_gate=cirq.google.SYC)
+    syc = FakeSycamoreGate()
+    ops = cirq.decompose_cphase_into_two_fsim(cirq.CZ, fsim_gate=syc)
     num_interaction_moments = 0
     for op in ops:
         assert len(op.qubits) in (0, 1, 2)
         if len(op.qubits) == 2:
             num_interaction_moments += 1
-            assert isinstance(op.gate, cirq.google.SycamoreGate)
+            assert isinstance(op.gate, FakeSycamoreGate)
     assert num_interaction_moments == 2
 
 
@@ -56,7 +62,7 @@ def assert_decomposition_valid(cphase_gate, fsim_gate):
 )
 def test_decomposition_to_sycamore_gate(exponent):
     cphase_gate = cirq.CZPowGate(exponent=exponent)
-    assert_decomposition_valid(cphase_gate, cirq.google.SYC)
+    assert_decomposition_valid(cphase_gate, FakeSycamoreGate())
 
 
 @pytest.mark.parametrize(

cirq/optimizers/two_qubit_to_fsim_test.py

@@ -26,7 +26,6 @@
 
 FEASIBLE_FSIM_GATES = [
     cirq.ISWAP,
-    cirq.google.SYC,
     cirq.FSimGate(np.pi / 2, 0),
     cirq.FSimGate(-np.pi / 2, 0),
     cirq.FSimGate(np.pi / 2, np.pi / 6),

cirq/protocols/json_test_data/TaggedOperation.json

@@ -18,7 +18,7 @@
   [
     "tag1",
     {
-      "cirq_type": "PhysicalZTag"
+      "cirq_type": "VirtualTag"
     }
   ]
 }

cirq/protocols/json_test_data/TaggedOperation.repr

@@ -1 +1 @@
-cirq.TaggedOperation(cirq.X.on(cirq.NamedQubit('q1')), 'tag1', cirq.google.PhysicalZTag())
+cirq.TaggedOperation(cirq.X.on(cirq.NamedQubit('q1')), 'tag1', cirq.ops.VirtualTag())

dev_tools/notebooks/notebook_test.py

@@ -23,6 +23,7 @@
 import glob
 import os
 import subprocess
+from logging import warning
 from typing import Set
 
 import pytest
@@ -45,8 +46,12 @@
 
 
 def _list_all_notebooks() -> Set[str]:
-    output = subprocess.check_output(['git', 'ls-files', '*.ipynb'])
-    return set(output.decode('utf-8').splitlines())
+    try:
+        output = subprocess.check_output(['git', 'ls-files', '*.ipynb'])
+        return set(output.decode('utf-8').splitlines())
+    except subprocess.CalledProcessError as ex:
+        warning("It seems that tests are run from not a git repo, notebook tests are skipped", ex)
+        return set()
 
 
 def _tested_notebooks():