feat: retain spaces before /* @if */ and after /* @endif */

This is a small breaking change from original preprocess. This new behaviour will help skeleton author to fine control output.

lib/preprocess/regex-rules.js

@@ -17,7 +17,7 @@ exports.js = {
     '//[ \t]*@eval[ \t]+(.*?)[ \t]*$'
   ],
   if: {
-    start: '[ \t]*(?://|/\\*)[ \t]*@if[ \t]+([^\n*]*)(?:\\*(?:\\*|/))?(?:[ \t]*\n+)?',
-    end  : '[ \t]*(?://|/\\*)[ \t]*@endif[ \t]*(?:\\*(?:\\*|/))?(?:[ \t]*\n)?'
+    start: '(?:[ \t]*//|/\\*)[ \t]*@if[ \t]+([^\n*]*)(?:(?:\\*(?:\\*|/))|(?:[ \t]*\n+))',
+    end  : '(?:[ \t]*//|/\\*)[ \t]*@endif[ \t]*(?:(?:\\*(?:\\*|/))|(?:[ \t]*\n))'
   },
 };

test/preprocess/if.spec.js

@@ -95,8 +95,8 @@ b
 /* @endif */
 c`;
 
-  t.is(preprocess(source, null, ['foo']), 'a\nb\nc');
-  t.is(preprocess(source, null, ['bar']), 'a\nc');
+  t.is(preprocess(source, null, ['foo']), 'a\n\nb\n\nc');
+  t.is(preprocess(source, null, ['bar']), 'a\n\nc');
 });
 
 test('@if complains about missing ending in js syntax with hidden syntax (block comment)', t => {
@@ -117,25 +117,21 @@ test('@if supports one line block comment in js syntax', t => {
 });
 
 test('@if supports nesting (block comment) in js syntax', t => {
-  const source = 'a/* @if foo */b/* @if bar */bad/* @endif */c/* @if foo */d/* @endif */e/* @endif */f';
-  t.is(preprocess(source, null, ['foo']), 'abcdef');
-  t.is(preprocess(source, null, ['bar']), 'af');
-  t.is(preprocess(source, null, ['foo', 'bar']), 'abbadcdef');
+  const source = 'a /* @if foo */b/* @if bar */bad/* @endif */ c/* @if foo */d/* @endif */e/* @endif */f';
+  t.is(preprocess(source, null, ['foo']), 'a b cdef');
+  t.is(preprocess(source, null, ['bar']), 'a f');
+  t.is(preprocess(source, null, ['foo', 'bar']), 'a bbad cdef');
 });
 
 test('@if supports nested condition in js syntax', t => {
   const source = `a
 // @if foo
 b
 // @if bar && xx
-d
-/* @if lo */
-e
-/* @endif */
+d/* @if lo */
+e/* @endif */
 // @endif
-/* @if xx **
-f
-/* @endif */
+/* @if xx **f/* @endif */
 // @endif
 c`;