GH#3 / RT#108682 - verify that preserved line comments get EOL

When a line comment is preserved as it contains a copyright, it should
be immediately followed by an EOL character.  Test and verify that this
is the case.

Author: bleargh45

Changes

@@ -5,6 +5,8 @@ Revision history for Perl extension JavaScript::Minifier::XS.
     - optimized memory allocations, by allocating Nodes in bulk, and being
       smarter about when we need to free/reallocate content buffers in Nodes
     - optimize whitespace collapsing
+    - GH#3 / RT#108682; fix whitespace reduction at end of preserved line
+      comment.  Thanks to Dan Goodliffe
 
 0.13      2020-12-30 21:46:29-08:00 America/Vancouver
     - POD cleanups; spelling, SYNOPSIS

XS.xs

@@ -599,7 +599,7 @@ int JsCanPrune(Node* node) {
             if (nodeIsPREFIXSIGIL(node) && next && nodeIsWHITESPACE(next))
                 return PRUNE_NEXT;
             /* remove whitespace before "postfix" sigils */
-            if (nodeIsPOSTFIXSIGIL(node) && prev && nodeIsWHITESPACE(prev))
+            if (nodeIsPOSTFIXSIGIL(node) && prev && nodeIsWHITESPACE(prev) && prev->prev && !nodeIsLINECOMMENT(prev->prev))
                 return PRUNE_PREVIOUS;
             /* remove whitespace (but NOT endspace) after closing brackets */
             if (next && nodeIsWHITESPACE(next) && !nodeIsENDSPACE(next) && (nodeIsCHAR(node,')') || nodeIsCHAR(node,'}') || nodeIsCHAR(node,']')))

t/minify.t

@@ -51,6 +51,17 @@ subtest 'comments' => sub {;
     is $got, $expect;
   };
 
+  subtest 'preserved copyright line comment gets EOL' => sub { # GH#3
+    my $given = q|
+      function foo() {
+        // copyright is preserved
+      }
+    |;
+    my $expect = qq|function foo(){// copyright is preserved\n}|;
+    my $got    = minify($given);
+    is $got, $expect;
+  };
+
   subtest 'inline block comment' => sub {
     my $given  = 'var foo /* remove */ = /* me too */ 3;';
     my $expect = 'var foo=3;';