Improve coverage for amazon_braket_backend.py to 99% by covering regi… by alisha-1000 · Pull Request #1082 · apache/mahout

alisha-1000 · 2026-02-23T09:46:56Z

Related Issues

Changes

Test

Why

The current coverage for qumat/amazon_braket_backend.py was around ~90%.
This PR improves coverage to 99% by adding unit tests for previously uncovered branches.

Improving coverage in backend modules increases reliability and ensures
correct handling of edge cases such as AWS session initialization and parameter filtering.

How

Added unit tests covering:

Backend initialization:
- Local simulator
- Default simulator
- Unsupported simulator type fallback
- Region-based AWS session creation
Gate helper wrappers (RX/RY/RZ/U and other single-qubit/multi-qubit gates)
execute_circuit:
- With parameters
- Without parameters
- Parameter filtering logic
get_final_state_vector:
- With parameters
- Without parameters
- Ensured state_vector() path is exercised
calculate_prob_zero edge cases

Coverage impact:

amazon_braket_backend.py: ~90% → 99%

Checklist

Added or updated unit tests for all changes
Added or updated documentation for all changes

…on handling, execution branches, and state vector path

guan404ming · 2026-02-23T12:01:43Z

Please help handle the pre-commit error in ci, thanks!

guan404ming · 2026-02-23T12:12:11Z

qdp/qdp-kernels/tests/amplitude_encode.rs

Why do we need this change?

alisha-1000 · 2026-02-23T15:07:51Z

Thanks for pointing this out @guan404ming @viiccwen . The Rust test changes were introduced unintentionally while addressing pre-commit checks. I’ve reverted them to keep this PR strictly scoped to improving amazon_braket_backend.py coverage.

Copilot

Pull request overview

Adds a dedicated test module to increase coverage of qumat/amazon_braket_backend.py by exercising backend initialization branches, gate wrapper helpers, circuit execution paths (with/without parameters), state-vector retrieval, and probability calculation edge cases.

Changes:

Added new unit tests for initialize_backend covering local/default/unsupported simulator selection and region-based session creation.
Added tests for basic gate wrappers plus RX/RY/RZ parameter vs numeric handling and U decomposition.
Added tests for execute_circuit, get_final_state_vector, and calculate_prob_zero edge cases.

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Copilot · 2026-02-24T03:17:00Z

testing/qumat/test_amazon_braket_backend.py

+        mock_boto.assert_called_once_with(region_name="us-west-2")
+        mock_aws_session.assert_called_once()
+        mock_device.assert_called_once()


test_initialize_backend_with_region only asserts that AwsSession() and AwsDevice() were called, but not that the region-derived boto3.Session(region_name=...) object is actually passed into AwsSession(boto_session=...) and that the resulting aws session is forwarded into AwsDevice(..., aws_session=...). Without these assertions, the test would still pass even if the region logic is broken or ignored.

Suggested change

mock_boto.assert_called_once_with(region_name="us-west-2")

mock_aws_session.assert_called_once()

mock_device.assert_called_once()

# Ensure boto3.Session is created with the configured region

mock_boto.assert_called_once_with(region_name="us-west-2")

# Ensure the boto3 session object is passed into AwsSession

mock_aws_session.assert_called_once_with(boto_session=mock_boto.return_value)

# Ensure the resulting AwsSession is forwarded into AwsDevice

mock_device.assert_called_once()

_, device_kwargs = mock_device.call_args

assert device_kwargs.get("aws_session") is mock_aws_session.return_value

Copilot · 2026-02-24T03:17:01Z

testing/qumat/test_amazon_braket_backend.py

+        "parameter_values": {"theta": 0.5},
+    }
+
+    execute_circuit(circuit, mock_backend, config)
+    mock_backend.run.assert_called_once()
+
+


test_execute_circuit_with_parameters doesn't assert that backend.run receives the expected inputs mapping (or that it filters to only circuit.parameters). As written, it would pass even if execute_circuit ignored parameter_values entirely. Add an assertion on mock_backend.run.call_args (and ideally the returned measurement counts) to lock in the intended behavior.

Suggested change

"parameter_values": {"theta": 0.5},

}

execute_circuit(circuit, mock_backend, config)

mock_backend.run.assert_called_once()

# Include an extra parameter to ensure only circuit.parameters are used.

"parameter_values": {"theta": 0.5, "phi": 0.7},

}

result = execute_circuit(circuit, mock_backend, config)

# Ensure backend.run was called once with the expected inputs mapping.

mock_backend.run.assert_called_once()

_, kwargs = mock_backend.run.call_args

assert "inputs" in kwargs

assert kwargs["inputs"] == {"theta": 0.5}

# Ensure the measurement counts from the backend are returned.

assert result == {"00": 1}

Copilot · 2026-02-24T03:17:01Z

testing/qumat/test_amazon_braket_backend.py

+    circuit.x.assert_called()
+    circuit.h.assert_called()
+    circuit.cnot.assert_called()
+    circuit.ccnot.assert_called()
+    circuit.swap.assert_called()
+    circuit.cswap.assert_called()
+    circuit.y.assert_called()
+    circuit.z.assert_called()
+    circuit.t.assert_called()


test_basic_gate_wrappers uses broad assert_called() checks, so it won’t fail if a wrapper calls the right method but with the wrong qubit indices/arity (and some calls like x happen twice). Consider switching to assert_called_once_with/assert_any_call per wrapper (or separate tests) so each wrapper’s signature and arguments are actually validated.

Suggested change

circuit.x.assert_called()

circuit.h.assert_called()

circuit.cnot.assert_called()

circuit.ccnot.assert_called()

circuit.swap.assert_called()

circuit.cswap.assert_called()

circuit.y.assert_called()

circuit.z.assert_called()

circuit.t.assert_called()

# apply_not_gate and apply_pauli_x_gate are both expected to call x on qubit 0

circuit.x.assert_any_call(0)

assert circuit.x.call_count >= 2

circuit.h.assert_called_once_with(1)

circuit.cnot.assert_called_once_with(0, 1)

circuit.ccnot.assert_called_once_with(0, 1, 2)

circuit.swap.assert_called_once_with(0, 1)

circuit.cswap.assert_called_once_with(0, 1, 2)

circuit.y.assert_called_once_with(1)

circuit.z.assert_called_once_with(2)

circuit.t.assert_called_once_with(0)

alisha-1000 · 2026-02-24T04:30:47Z

@ryankert01 Hi, I’ve addressed the Copilot feedback and updated the tests accordingly.
Could you please approve the workflows so that CI can run?
Thank you!

guan404ming

LGTM

Improve coverage for amazon_braket_backend.py to 99% by covering regi…

8e7ae39

…on handling, execution branches, and state vector path

alisha-1000 mentioned this pull request Feb 23, 2026

[Feature] Enhance Module Testing Coverage #1058

Closed

Apply cargo fmt and fix clippy dead code warning

c84c08a

alisha-1000 requested a review from ryankert01 as a code owner February 23, 2026 12:09

guan404ming reviewed Feb 23, 2026

View reviewed changes

Revert unintended Rust test changes

07347bb

ryankert01 requested a review from Copilot February 24, 2026 03:14

Copilot started reviewing on behalf of ryankert01 February 24, 2026 03:14 View session

Copilot AI reviewed Feb 24, 2026

View reviewed changes

alisha-1000 and others added 2 commits February 24, 2026 09:32

Merge branch 'main' into improve-amazon-braket-backend-coverage

64fcac9

Apply ruff formatting and strengthen tests

b559504

guan404ming approved these changes Feb 24, 2026

View reviewed changes

guan404ming merged commit bdc1a7b into apache:main Feb 24, 2026
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Improve coverage for amazon_braket_backend.py to 99% by covering regi…#1082

Improve coverage for amazon_braket_backend.py to 99% by covering regi…#1082
guan404ming merged 5 commits intoapache:mainfrom
alisha-1000:improve-amazon-braket-backend-coverage

alisha-1000 commented Feb 23, 2026

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-        mock_boto.assert_called_once_with(region_name="us-west-2")
-        mock_aws_session.assert_called_once()
-        mock_device.assert_called_once()
+        # Ensure boto3.Session is created with the configured region
+        mock_boto.assert_called_once_with(region_name="us-west-2")
+        # Ensure the boto3 session object is passed into AwsSession
+        mock_aws_session.assert_called_once_with(boto_session=mock_boto.return_value)
+        # Ensure the resulting AwsSession is forwarded into AwsDevice
+        mock_device.assert_called_once()
+        _, device_kwargs = mock_device.call_args
+        assert device_kwargs.get("aws_session") is mock_aws_session.return_value

-        "parameter_values": {"theta": 0.5},
-    }
-    execute_circuit(circuit, mock_backend, config)
-    mock_backend.run.assert_called_once()
+        # Include an extra parameter to ensure only circuit.parameters are used.
+        "parameter_values": {"theta": 0.5, "phi": 0.7},
+    }
+    result = execute_circuit(circuit, mock_backend, config)
+    # Ensure backend.run was called once with the expected inputs mapping.
+    mock_backend.run.assert_called_once()
+    _, kwargs = mock_backend.run.call_args
+    assert "inputs" in kwargs
+    assert kwargs["inputs"] == {"theta": 0.5}
+    # Ensure the measurement counts from the backend are returned.
+    assert result == {"00": 1}

-    circuit.x.assert_called()
-    circuit.h.assert_called()
-    circuit.cnot.assert_called()
-    circuit.ccnot.assert_called()
-    circuit.swap.assert_called()
-    circuit.cswap.assert_called()
-    circuit.y.assert_called()
-    circuit.z.assert_called()
-    circuit.t.assert_called()
+    # apply_not_gate and apply_pauli_x_gate are both expected to call x on qubit 0
+    circuit.x.assert_any_call(0)
+    assert circuit.x.call_count >= 2
+    circuit.h.assert_called_once_with(1)
+    circuit.cnot.assert_called_once_with(0, 1)
+    circuit.ccnot.assert_called_once_with(0, 1, 2)
+    circuit.swap.assert_called_once_with(0, 1)
+    circuit.cswap.assert_called_once_with(0, 1, 2)
+    circuit.y.assert_called_once_with(1)
+    circuit.z.assert_called_once_with(2)
+    circuit.t.assert_called_once_with(0)

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alisha-1000 commented Feb 23, 2026

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