Adds test for variants of "normalized" workds like filehandle

New words should be added to the `%variants` hash when they are
effectively normalized. Closes #2041

doc/Type/X/IO/DoesNotExist.pod6

@@ -7,7 +7,7 @@
 =for code :skip-test
 class X::IO::DoesNotExist does X::IO is Exception { }
 
-Thrown when doing e.g. file test operations on a non existing path.
+Thrown when doing file test operations on a non existing path.
 
 A typical error message is
 

xt/word-variants.t

@@ -0,0 +1,40 @@
+#!/usr/bin/env perl6
+
+use v6;
+use Test;
+use lib 'lib';
+use Test-Files;
+
+=begin overview
+
+Insure any text that mentions Perl uses a no-break space after it.
+
+=end overview
+
+my @files = Test-Files.documents;
+
+my %variants = %( "file handle" | "file-handle" => "filehandle" );
+plan +@files;
+
+for @files.sort -> $file {
+    my $ok = True;
+    my $row = 0;
+    my @bad;
+    for $file.IO.slurp.lines -> $line {
+        $row++;
+        next if $line ~~ / ^ \s+ /;
+        for %variants.keys -> $rx {
+            if $line ~~ m:g/ $rx / {
+                $ok = False;
+                @bad.push: "«$0» found in line $row. We prefer ｢%variants{$rx}｣";
+            }
+        }
+    }
+    my $error = $file;
+    if !$ok {
+        $error ~= " {@bad.join: ', '})";
+    }
+    ok $ok, "$error: Certain words should be normalized." ;
+}
+
+# vim: expandtab shiftwidth=4 ft=perl6