Add a test to avoid using ".." after a word

(typically you mean either . or ...)

Closes #1632

Author: coke

doc/Language/5to6-perlop.pod6

@@ -94,7 +94,7 @@ use C<@ones = 1 xx 80;>.
 =head2 Additive Operators
 
 Binary C<+> and C<-> do addition and subtraction, respectively, as you would
-expect..
+expect.
 
 As C<.> is the method call operator, so binary C<~> acts as the
 concatenation operator in Perl 6.

doc/Type/Cool.pod6

@@ -817,7 +817,7 @@ Defined as:
 
 Coerces the invocant (or in sub form, its argument) to L<Str|/type/Str>, and returns it with the first letter
 case-folded to title case (or where not available, upper case), and the rest
-of the string case-folded to lower case..
+of the string case-folded to lower case.
 
     say 'abC'.tclc;     # OUTPUT: «Abc␤»
 

doc/Type/IO/Spec/Win32.pod6

@@ -12,7 +12,7 @@ an object of the appropriate type
 
 B<NOTE:> the C<IO::Spec::*> classes provide low-level path operations. Unless
 you're creating your own high-level path manipulation routines, you don't
-need to use C<IO::Spec::*>. Use L«C<IO::Path>|/type/IO::Path» instead..
+need to use C<IO::Spec::*>. Use L«C<IO::Path>|/type/IO::Path» instead.
 
 B<NOTE2:> no special validation is done by these classes (e.g. check whether
 path contains a null character). It is the job of higher-level classes, like

doc/Type/Metamodel/ClassHOW.pod6

@@ -49,7 +49,7 @@ the method cache.
 
 If C<$condition> returns a true value,
 C<$calculator> is called with the same arguments, and must return the code
-object to be invoked as the method, and is added to the method cache..
+object to be invoked as the method, and is added to the method cache.
 
 If C<$condition> returns a false value, the
 next fallback (if any) is tried, and if none matches, an exception

xt/double-dots.t

@@ -0,0 +1,69 @@
+#!/usr/bin/env perl6
+
+use v6;
+use Test;
+use lib 'lib';
+
+=begin overview
+
+Avoid using C<..> - usually a typo for C<.> or C<...>
+
+=end overview
+
+my @files;
+
+if @*ARGS {
+    @files = @*ARGS;
+} else {
+    if %*ENV<TEST_FILES> {
+        @files = %*ENV<TEST_FILES>.split(' ').grep(*.IO.e);
+    } else {
+        @files = qx<git ls-files>.lines;
+    }
+}
+
+@files = @files.grep({$_.ends-with('.pod6') or $_.ends-with('.md')});
+
+plan +@files;
+my $max-jobs = %*ENV<TEST_THREADS> // 2;
+my %output;
+
+sub test-promise($promise) {
+    my $file = $promise.command[*-1];
+    test-it(%output{$file}, $file);
+}
+
+sub test-it(Str $output, Str $file) {
+    my $ok = True;
+
+    for $output.lines -> $line {
+        if $line ~~ / <alpha> '..' (<space> | $) / {
+            diag "Failure on line `$line`";
+            $ok = False;
+        }
+    }
+    my $error = $file;
+    ok $ok, "$error: file contains ..";
+}
+
+my @jobs;
+for @files -> $file {
+
+    my $output = "";
+
+    if $file ~~ / '.pod6' $/ {
+        my $a = Proc::Async.new($*EXECUTABLE-NAME, '--doc', $file);
+        %output{$file} = "";
+        $a.stdout.tap(-> $buf { %output{$file} = %output{$file} ~ $buf });
+        push @jobs: $a.start;
+        if +@jobs > $max-jobs {
+            test-promise(await @jobs.shift)
+        }
+    } else {
+        test-it($file.IO.slurp, $file);
+    }
+}
+
+for @jobs.map: {await $_} -> $r { test-promise($r) }
+
+# vim: expandtab shiftwidth=4 ft=perl6