review comments

- additional test if litinski is noop
- update test names
- remove some idle code

Author: Cryoris

crates/cext/src/transpiler/passes/litinski_transformation.rs

@@ -38,11 +38,9 @@ pub unsafe extern "C" fn qk_transpiler_pass_standalone_litinski_transformation(
 ) {
     // SAFETY: The user guarantees the pointer is safe to read.
     let circuit = unsafe { mut_ptr_as_ref(circuit) };
-    let dag = match DAGCircuit::from_circuit_data(circuit, false, None, None, None, None) {
-        Ok(dag) => dag,
-        Err(_) => panic!("Internal Circuit -> DAG conversion failed"),
-    };
-    // TODO: Potentially propagate exit code to the user
+    let dag = DAGCircuit::from_circuit_data(circuit, false, None, None, None, None)
+        .expect("Internal Circuit -> DAG conversion failed");
+
     let maybe_out = run_litinski_transformation(&dag, fix_clifford, false, true)
         .expect("Failed running Litinski transformation");
     // If a DAG is returned, the circuit has been modified. Else just leave it as is.

test/c/test_pbc.c

@@ -23,7 +23,7 @@
 /**
  * Test gate counts after Litinski transformation.
  */
-static int test_counts(void) {
+static int test_counts_litinski(void) {
     QkCircuit *circuit = qk_circuit_new(4, 0);
     qk_circuit_gate(circuit, QkGate_H, (uint32_t[1]){0}, NULL);
     qk_circuit_gate(circuit, QkGate_CX, (uint32_t[2]){0, 1}, NULL);
@@ -50,6 +50,7 @@ static int test_counts(void) {
             }
         }
     }
+    qk_opcounts_clear(&op_counts);
 cleanup:
     qk_circuit_free(circuit);
     return result;
@@ -58,7 +59,7 @@ static int test_counts(void) {
 /**
  * Test gate counts after converting to Pauli rotations.
  */
-static int test_counts_pauli_rotations(void) {
+static int test_counts_convert_to_pauli_rotations(void) {
     QkCircuit *circuit = qk_circuit_new(4, 2);
     qk_circuit_gate(circuit, QkGate_H, (uint32_t[1]){0}, NULL);     // 2 PPR gates
     qk_circuit_gate(circuit, QkGate_CX, (uint32_t[2]){0, 1}, NULL); // 3 PPR gates
@@ -194,6 +195,9 @@ int check_pauli_rotation(QkCircuit *circuit, size_t index, enum Pauli *paulis, u
     return result;
 }
 
+/**
+ * A helper to check a PPM matches the expectation.
+ */
 int check_pauli_measurement(QkCircuit *circuit, size_t index, enum Pauli *paulis, uint32_t *qubits,
                             const size_t len, uint32_t clbit, bool flip_outcome) {
     QkPauliProductMeasurement ppm;
@@ -243,7 +247,7 @@ int check_pauli_measurement(QkCircuit *circuit, size_t index, enum Pauli *paulis
 /**
  * Test concrete circuit after running the Litinski transformation.
  */
-static int test_concrete(void) {
+static int test_concrete_litinski(void) {
     QkCircuit *circuit = qk_circuit_new(4, 4);
     qk_circuit_gate(circuit, QkGate_T, (uint32_t[1]){0}, NULL);
     qk_circuit_gate(circuit, QkGate_CX, (uint32_t[2]){2, 1}, NULL);
@@ -304,17 +308,14 @@ static int test_concrete(void) {
 /**
  * Test concrete circuit after running conversion to Pauli rotations.
  */
-static int test_concrete_pauli_rotations(void) {
+static int test_concrete_convert_to_pauli_rotations(void) {
     QkCircuit *circuit = qk_circuit_new(4, 1);
     qk_circuit_gate(circuit, QkGate_T, (uint32_t[1]){0}, NULL);
     qk_circuit_gate(circuit, QkGate_H, (uint32_t[2]){1}, NULL);
     qk_circuit_gate(circuit, QkGate_RXX, (uint32_t[2]){2, 3}, (double[1]){1.0});
     qk_circuit_gate(circuit, QkGate_SXdg, (uint32_t[1]){3}, NULL);
     qk_circuit_measure(circuit, 0, 0);
 
-    for (uint32_t i = 0; i < 4; i++) {
-    }
-
     qk_transpiler_pass_standalone_convert_to_pauli_rotations(circuit);
 
     int result = Ok;
@@ -341,13 +342,44 @@ static int test_concrete_pauli_rotations(void) {
     qk_circuit_free(circuit);
     return result;
 }
+
+/**
+ * Test Litinski not doing anything.
+ */
+static int test_litinski_noop(void) {
+    QkCircuit *circuit = qk_circuit_new(1, 0);
+    qk_circuit_gate(circuit, QkGate_H, (uint32_t[1]){0}, NULL);
+
+    qk_transpiler_pass_standalone_litinski_transformation(circuit, true);
+
+    int result = Ok;
+    if (qk_circuit_num_instructions(circuit) != 1) {
+        printf("Expected 1 instructions, but found %zu", qk_circuit_num_instructions(circuit));
+        result = EqualityError;
+        goto cleanup;
+    }
+
+    QkCircuitInstruction inst;
+    qk_circuit_get_instruction(circuit, 0, &inst);
+    if (strcmp(inst.name, "h") != 0) {
+        printf("Instruction at index 0 should be 'h' but is '%s'", inst.name);
+        result = EqualityError;
+    }
+    qk_circuit_instruction_clear(&inst);
+
+cleanup:
+    qk_circuit_free(circuit);
+    return result;
+}
+
 int test_pbc(void) {
     int num_failed = 0;
 
-    num_failed += RUN_TEST(test_counts);
-    num_failed += RUN_TEST(test_counts_pauli_rotations);
-    num_failed += RUN_TEST(test_concrete);
-    num_failed += RUN_TEST(test_concrete_pauli_rotations);
+    num_failed += RUN_TEST(test_counts_litinski);
+    num_failed += RUN_TEST(test_counts_convert_to_pauli_rotations);
+    num_failed += RUN_TEST(test_concrete_litinski);
+    num_failed += RUN_TEST(test_concrete_convert_to_pauli_rotations);
+    num_failed += RUN_TEST(test_litinski_noop);
 
     fflush(stderr);
     fprintf(stderr, "=== Number of failed subtests (PBC transformations): %i\n", num_failed);