Add debug var for dumping STDERR of t/pod-valid.t failures

And simplify code a bit (the tap receives a Str not a buf and there's
no point in assigning it to a param if we never use it);

Author: zoffixznet

README.md

@@ -159,6 +159,11 @@ explains briefly how to get started contributing documentation.
         #= P<p6doc/&note>
         sub note(|$) { ... }
 
+# ENV VARS
+
+Set `PERL6_DOC_TEST_VERSBOSE` to a true value to display verbose messages during test suite run.
+Helpful when debugging failing test suite.
+
 # LICENSE
 
 See [LICENSE](LICENSE) file for the details of the license of the code in this repository.

t/pod-valid.t

@@ -28,8 +28,11 @@ my @jobs;
 %data{@files} = 0 xx @files;
 for @files -> $file {
     my $p =  Proc::Async.new($*EXECUTABLE-NAME, '--doc', $file);
-    $p.stdout.tap(-> $buf {});
-    $p.stderr.tap(-> $buf { %data{$file} = 1 });
+    $p.stdout.tap: {;};
+    $p.stderr.tap: {
+        %*ENV<PERL6_DOC_TEST_VERSBOSE> and diag "$file STDERR: $_";
+        %data{$file} = 1;
+    }
     push @jobs: $p.start;
     if +@jobs > $max-jobs {
         test-it(await @jobs.shift);