Update error messages, add diagram tests, and update measure to measu…

…re all qubits when no targets provided

src/braket/circuits/circuit.py

@@ -641,7 +641,7 @@ def add_verbatim_box(
             raise ValueError("Verbatim subcircuit is not measured and cannot have result types")
 
         if verbatim_circuit._measure_targets:
-            raise ValueError("Verbatim subcircuit is not measured.")
+            raise ValueError("Cannot measure a subcircuit inside a verbatim box.")
 
         if verbatim_circuit.instructions:
             self.add_instruction(Instruction(compiler_directives.StartVerbatimBox()))
@@ -651,7 +651,7 @@ def add_verbatim_box(
             self._has_compiler_directives = True
         return self
 
-    def measure(self, target_qubits: np.ndarray | int = []) -> Circuit:
+    def measure(self, target_qubits: np.ndarray | int = None) -> Circuit:
         """
         Add a `measure` operator to `self` ensuring only the target qubits are measured.
 
@@ -682,28 +682,39 @@ def measure(self, target_qubits: np.ndarray | int = []) -> Circuit:
             target_qubits = [target_qubits]
 
         # Check that the target qubits are on the circuit
-        if not all(qubit in self.qubits for qubit in target_qubits):
+        if target_qubits and not all(qubit in self.qubits for qubit in target_qubits):
             raise IndexError("Target qubits must be within the range of the current circuit.")
 
         # Check if result types are added on the circuit
         if self.result_types:
-            raise ValueError("Cannot perform a measure instruction with a result type.")
+            raise ValueError("a circuit cannot contain both measure instructions and result types.")
 
         # Check if there is more than one measure instruction
         if any(isinstance(instruction.operator, Measure) for instruction in self.instructions):
             raise ValueError("Cannot perform more than one measure instruction.")
 
         if target_qubits:
-            for idx, target in enumerate(target_qubits):
-                self.add_instruction(
-                    Instruction(
-                        operator=Measure(qubit_count=1, ascii_symbols=["M"], index=idx),
-                        target=target,
-                    )
+            self.add_instruction(
+                Instruction(
+                    operator=Measure(
+                        qubit_count=len(target_qubits), ascii_symbols=["M"] * len(target_qubits)
+                    ),
+                    target=target_qubits,
                 )
+            )
             self._measure_targets = target_qubits
         else:
-            raise ValueError("Measure must include one or more target qubits.")
+            # Measure all the qubits
+            self.add_instruction(
+                Instruction(
+                    operator=Measure(
+                        qubit_count=self.qubit_count, ascii_symbols=["M"] * self.qubit_count
+                    ),
+                    target=self.qubits,
+                )
+            )
+            self._measure_targets = self.qubits
+
         return self
 
     def apply_gate_noise(

src/braket/circuits/measure.py

@@ -28,9 +28,7 @@
 class Measure(QuantumOperator):
     """Class `Measure` represents a measure operation on targeted qubits"""
 
-    def __init__(
-        self, qubit_count: Optional[int] = 1, ascii_symbols: Sequence[str] = ["M"], **kwargs
-    ):
+    def __init__(self, qubit_count: Optional[int] = 1, ascii_symbols: Sequence[str] = ["M"]):
         """Inits a `Measure`.
 
         Args:
@@ -44,11 +42,6 @@ def __init__(
                 `ascii_symbols` length != `qubit_count`
         """
         super().__init__(qubit_count=qubit_count, ascii_symbols=ascii_symbols)
-        self._target_index = kwargs.get("index")
-
-    @property
-    def name(self) -> str:
-        return self.__class__.__name__
 
     @property
     def ascii_symbols(self) -> tuple[str, ...]:
@@ -89,7 +82,7 @@ def to_ir(
 
     def _to_jaqcd(self) -> Any:
         """Returns the JAQCD representation of the measure."""
-        raise NotImplementedError("to_jaqcd has not been implemented yet.")
+        raise NotImplementedError("Measure instructions are not supported with JAQCD.")
 
     def _to_openqasm(
         self, target: QubitSet, serialization_properties: OpenQASMSerializationProperties
@@ -98,12 +91,12 @@ def _to_openqasm(
         target_qubits = [serialization_properties.format_target(int(qubit)) for qubit in target]
         instructions = ""
         for idx, qubit in enumerate(target_qubits):
-            instructions += f"b[{self._target_index}] = measure {qubit};"
+            instructions += f"b[{idx}] = measure {qubit};"
 
         return instructions
 
     def __eq__(self, other: Measure):
-        return isinstance(other, Measure) and self.name == other.name
+        return isinstance(other, Measure) and self.qubit_count == other.qubit_count
 
     def __repr__(self):
         return self.name

test/integ_tests/test_measure.py

@@ -60,7 +60,6 @@ def test_measure_on_supported_devices(arn):
         pytest.skip("Device offline")
     circ = Circuit().h(0).cnot(0, 1).measure([0])
     result = device.run(circ, SHOTS).result()
-    print(result)
     assert len(result.measurements[0]) == 1
     assert result.measured_qubits == [0]
 
@@ -74,7 +73,6 @@ def test_measure_on_supported_devices(arn):
 )
 def test_measure_targets(circuit, expected_measured_qubits):
     result = DEVICE.run(circuit, SHOTS).result()
-    print(result)
     assert result.measured_qubits == expected_measured_qubits
     assert len(result.measurements[0]) == len(expected_measured_qubits)
 

test/unit_tests/braket/circuits/test_ascii_circuit_diagram.py

@@ -886,3 +886,21 @@ def test_measure():
         "T  : |0|1|2|",
     )
     _assert_correct_diagram(circ, expected)
+
+
+def test_measure_multiple_targets():
+    circ = Circuit().h(0).cnot(0, 1).cnot(1, 2).cnot(2, 3).measure([0, 2, 3])
+    expected = (
+        "T  : |0|1|2|3|4|",
+        "                ",
+        "q0 : -H-C-----M-",
+        "        |     | ",
+        "q1 : ---X-C---|-",
+        "          |   | ",
+        "q2 : -----X-C-M-",
+        "            | | ",
+        "q3 : -------X-M-",
+        "",
+        "T  : |0|1|2|3|4|",
+    )
+    _assert_correct_diagram(circ, expected)

test/unit_tests/braket/circuits/test_circuit.py

@@ -602,9 +602,9 @@ def test_measure_multiple_targets():
         .add_instruction(Instruction(Gate.CNot(), [0, 1]))
         .add_instruction(Instruction(Gate.CNot(), [1, 2]))
         .add_instruction(Instruction(Gate.CNot(), [2, 3]))
-        .add_instruction(Instruction(Measure(), 0))
-        .add_instruction(Instruction(Measure(), 1))
-        .add_instruction(Instruction(Measure(), 3))
+        .add_instruction(
+            Instruction(Measure(qubit_count=3, ascii_symbols=["M", "M", "M"]), [0, 1, 3])
+        )
     )
     assert circ == expected
     assert circ._measure_targets == [0, 1, 3]
@@ -653,7 +653,7 @@ def test_measure_verbatim_box():
 
 
 def test_measure_in_verbatim_subcircuit():
-    message = "Verbatim subcircuit is not measured."
+    message = "Cannot measure a subcircuit inside a verbatim box."
     with pytest.raises(ValueError, match=message):
         Circuit().add_verbatim_box(Circuit().x(0).x(1).measure(0))
 
@@ -669,13 +669,18 @@ def test_measure_empty_circuit():
 
 
 def test_measure_no_target():
-    message = "Measure must include one or more target qubits."
-    with pytest.raises(ValueError, match=message):
-        Circuit().h(0).cnot(0, 1).measure()
+    circ = Circuit().h(0).cnot(0, 1).measure()
+    expected = (
+        Circuit()
+        .add_instruction(Instruction(Gate.H(), 0))
+        .add_instruction(Instruction(Gate.CNot(), [0, 1]))
+        .add_instruction(Instruction(Measure(qubit_count=2, ascii_symbols=["M", "M"]), [0, 1]))
+    )
+    assert circ == expected
 
 
 def test_measure_with_result_types():
-    message = "Cannot perform a measure instruction with a result type."
+    message = "a circuit cannot contain both measure instructions and result types."
     with pytest.raises(ValueError, match=message):
         Circuit().h(0).sample(observable=Observable.Z(), target=0).measure(0)
 

test/unit_tests/braket/circuits/test_measure.py

@@ -29,7 +29,7 @@ def ascii_symbols():
 
 @pytest.fixture
 def measure(ascii_symbols):
-    return Measure(qubit_count=1, ascii_symbols=ascii_symbols, index=0)
+    return Measure(qubit_count=1, ascii_symbols=ascii_symbols)
 
 
 def test_is_operator(measure):
@@ -55,19 +55,19 @@ def test_equality():
     assert measure1 != non_measure
 
 
-def test_name(measure):
-    expected = measure.__class__.__name__
-    assert measure.name == expected
-
-
 def test_str(measure):
     assert str(measure) == measure.name
 
 
 @pytest.mark.parametrize(
     "ir_type, serialization_properties, expected_exception, expected_message",
     [
-        (IRType.JAQCD, None, NotImplementedError, "to_jaqcd has not been implemented yet."),
+        (
+            IRType.JAQCD,
+            None,
+            NotImplementedError,
+            "Measure instructions are not supported with JAQCD.",
+        ),
         ("invalid-ir-type", None, ValueError, "Supplied ir_type invalid-ir-type is not supported."),
     ],
 )
@@ -83,16 +83,16 @@ def test_measure_to_ir(
     "measure, target, serialization_properties, expected_ir",
     [
         (
-            Measure(qubit_count=1, ascii_symbols=["M"], index=0),
+            Measure(),
             [0],
             OpenQASMSerializationProperties(qubit_reference_type=QubitReferenceType.VIRTUAL),
             "b[0] = measure q[0];",
         ),
         (
-            Measure(qubit_count=1, ascii_symbols=["M"], index=1),
-            [4],
+            Measure(qubit_count=4, ascii_symbols=["M", "M", "M", "M"]),
+            [1, 4],
             OpenQASMSerializationProperties(qubit_reference_type=QubitReferenceType.PHYSICAL),
-            "b[1] = measure $4;",
+            "b[0] = measure $1;b[1] = measure $4;",
         ),
     ],
 )

test/unit_tests/braket/circuits/test_unicode_circuit_diagram.py

@@ -1019,3 +1019,24 @@ def __init__(self):
         "T  : │    0     │",
     )
     _assert_correct_diagram(circ, expected)
+
+
+def test_measure():
+    circ = circ = Circuit().h(0).cnot(0, 1).cnot(1, 2).cnot(2, 3).measure([0, 2, 3])
+    expected = (
+        "T  : │  0  │  1  │  2  │  3  │  4  │",
+        "      ┌───┐                   ┌───┐ ",
+        "q0 : ─┤ H ├───●───────────────┤ M ├─",
+        "      └───┘   │               └─┬─┘ ",
+        "            ┌─┴─┐               │   ",
+        "q1 : ───────┤ X ├───●───────────┼───",
+        "            └───┘   │           │   ",
+        "                  ┌─┴─┐       ┌─┴─┐ ",
+        "q2 : ─────────────┤ X ├───●───┤ M ├─",
+        "                  └───┘   │   └─┬─┘ ",
+        "                        ┌─┴─┐ ┌─┴─┐ ",
+        "q3 : ───────────────────┤ X ├─┤ M ├─",
+        "                        └───┘ └───┘ ",
+        "T  : │  0  │  1  │  2  │  3  │  4  │",
+    )
+    _assert_correct_diagram(circ, expected)