exclude lines from coverage report (#12564) (#12570)

* exclude lines from coverage

* comments with explanation

* to pyproject from tox

(cherry picked from commit 2d6a5a2)

Co-authored-by: Luciano Bello <bel@zurich.ibm.com>

pyproject.toml

@@ -240,3 +240,12 @@ enable = [
 
 [tool.pylint.spelling]
 spelling-private-dict-file = ".local-spellings"
+
+[tool.coverage.report]
+exclude_also = [
+    "def __repr__",               # Printable epresentational string does not typically execute during testing
+    "raise NotImplementedError",  # Abstract methods are not testable
+    "raise RuntimeError",         # Exceptions for defensive programming that cannot be tested a head
+    "if TYPE_CHECKING:",          # Code that only runs during type checks
+    "@abstractmethod",            # Abstract methods are not testable
+    ]

qiskit/qasm3/exporter.py

@@ -837,7 +837,7 @@ def build_current_scope(self) -> List[ast.Statement]:
                     statements.append(self.build_if_statement(instruction))
                 elif isinstance(instruction.operation, SwitchCaseOp):
                     statements.extend(self.build_switch_statement(instruction))
-                else:  # pragma: no cover
+                else:
                     raise RuntimeError(f"unhandled control-flow construct: {instruction.operation}")
                 continue
             # Build the node, ignoring any condition.
@@ -1130,7 +1130,7 @@ def _build_ast_type(type_: types.Type) -> ast.ClassicalType:
         return ast.BoolType()
     if type_.kind is types.Uint:
         return ast.UintType(type_.width)
-    raise RuntimeError(f"unhandled expr type '{type_}'")  # pragma: no cover
+    raise RuntimeError(f"unhandled expr type '{type_}'")
 
 
 class _ExprBuilder(expr.ExprVisitor[ast.Expression]):