lab: improvements to coverage-goals

- Warning up-front

- Works for line-only measurement

- Correct the command description.

Author: nedbat

lab/goals.py

@@ -18,13 +18,9 @@
 
 from wcmatch import fnmatch as wcfnmatch    # python -m pip install wcmatch
 
-from coverage.results import Numbers    # Note: an internal class!
+from coverage.results import Numbers        # Note: an internal class!
 
 
-def get_data():
-    with open("coverage.json") as j:
-        return json.load(j)
-
 def select_files(files, pat):
     flags = wcfnmatch.NEGATE | wcfnmatch.NEGATEALL
     selected = [f for f in files if wcfnmatch.fnmatch(f, pat, flags=flags)]
@@ -38,30 +34,35 @@ def total_for_files(data, files):
             n_statements=sel_summ["num_statements"],
             n_excluded=sel_summ["excluded_lines"],
             n_missing=sel_summ["missing_lines"],
-            n_branches=sel_summ["num_branches"],
-            n_partial_branches=sel_summ["num_partial_branches"],
-            n_missing_branches=sel_summ["missing_branches"],
+            n_branches=sel_summ.get("num_branches", 0),
+            n_partial_branches=sel_summ.get("num_partial_branches", 0),
+            n_missing_branches=sel_summ.get("missing_branches", 0),
             )
 
     return total
 
 def main(argv):
-    parser = argparse.ArgumentParser(__doc__)
+    parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument("--file", "-f", action="store_true", help="Check each file individually")
     parser.add_argument("--group", "-g", action="store_true", help="Check a group of files")
     parser.add_argument("--verbose", "-v", action="store_true", help="Be chatty about what's happening")
     parser.add_argument("goal", type=float, help="Coverage goal")
     parser.add_argument("pattern", type=str, nargs="+", help="Patterns to check")
     args = parser.parse_args(argv)
 
+    print("** Note: this is a proof-of-concept. Support is not promised. **")
+    print("Read more: https://nedbatchelder.com/blog/202111/coverage_goals.html")
+    print("Feedback is appreciated: https://github.com/nedbat/coveragepy/issues/691")
+
     if args.file and args.group:
         print("Can't use --file and --group together")
         return 1
     if not (args.file or args.group):
         print("Need either --file or --group")
         return 1
 
-    data = get_data()
+    with open("coverage.json") as j:
+        data = json.load(j)
     all_files = list(data["files"].keys())
     selected = select_files(all_files, args.pattern)