Merge bitcoin/bitcoin#29329: fuzz: Print coverage summary after run_once

fab97d81ce fuzz: Print coverage summary after run_once (MarcoFalke)

Pull request description:

  This can be used to quickly check the coverage effects of a code change or qa-assets change.

ACKs for top commit:
  dergoegge:
    ACK fab97d81ce

Tree-SHA512: 0ac913c14698f39e76e0e7bf124f182220031796d6443edb34c6e4615e128157cf746da661b216c4640a41964e977249712445ca9c005b1b4a3737adabdb4a7d

test/fuzz/test_runner.py

@@ -348,13 +348,18 @@ def run_once(*, fuzz_pool, corpus, test_list, src_dir, build_dir, using_libfuzze
                 text=True,
             )
             output += result.stderr
-            return output, result
+            return output, result, t
 
         jobs.append(fuzz_pool.submit(job, t, args))
 
+    stats = []
     for future in as_completed(jobs):
-        output, result = future.result()
+        output, result, target = future.result()
         logging.debug(output)
+        if using_libfuzzer:
+            done_stat = [l for l in output.splitlines() if "DONE" in l]
+            assert len(done_stat) == 1
+            stats.append((target, done_stat[0]))
         try:
             result.check_returncode()
         except subprocess.CalledProcessError as e:
@@ -365,6 +370,13 @@ def run_once(*, fuzz_pool, corpus, test_list, src_dir, build_dir, using_libfuzze
             logging.info(f"Target {result.args} failed with exit code {e.returncode}")
             sys.exit(1)
 
+    if using_libfuzzer:
+        print("Summary:")
+        max_len = max(len(t[0]) for t in stats)
+        for t, s in sorted(stats):
+            t = t.ljust(max_len + 1)
+            print(f"{t}{s}")
+
 
 def parse_test_list(*, fuzz_bin):
     test_list_all = subprocess.run(