wip

Author: nedbat

coverage/bytecode.py

@@ -8,7 +8,7 @@
 import collections
 import dis
 from types import CodeType
-from typing import Iterable, Optional
+from typing import Iterable, Mapping, Optional
 
 from coverage.types import TArc, TLineNo, TOffset
 
@@ -31,7 +31,9 @@ def op_set(*op_names: str) -> set[int]:
 
     The names might not exist in this version of Python, skip those if not.
     """
-    return {op for name in op_names if (op := dis.opmap.get(name))}
+    ops = {op for name in op_names if (op := dis.opmap.get(name))}
+    assert ops, f"At least one opcode must exist: {op_names}"
+    return ops
 
 
 # Opcodes that are unconditional jumps elsewhere.
@@ -99,10 +101,16 @@ def walk(
 TBranchTrails = dict[TOffset, TBranchTrailsOneSource]
 
 
-def branch_trails(code: CodeType, multiline_map: dict[TLineNo, TLineNo]) -> TBranchTrails:
+def branch_trails(
+    code: CodeType,
+    multiline_map: Mapping[TLineNo, TLineNo],
+) -> TBranchTrails:
     """
     Calculate branch trails for `code`.
 
+    `multiline_map` maps line numbers to the first line number of a
+    multi-line statement.
+
     Instructions can have a jump_target, where they might jump to next.  Some
     instructions with a jump_target are unconditional jumps (ALWAYS_JUMPS), so
     they aren't interesting to us, since they aren't the start of a branch