Fix fenced code in lists (russross#521)

This attempts to fix russross#495 and russross#485.

Note the test cases which were added at the bottom of the list. The first added test case was passing even before the changes, but the second was not.

block.go

@@ -649,14 +649,17 @@ func isFenceLine(data []byte, info *string, oldmarker string, newlineOptional bo
 	}
 
 	i = skipChar(data, i, ' ')
-	if i >= len(data) || data[i] != '\n' {
-		if newlineOptional && i == len(data) {
+	if i >= len(data) {
+		if newlineOptional {
 			return i, marker
 		}
 		return 0, ""
 	}
+	if data[i] == '\n' {
+		i++ // Take newline into account
+	}
 
-	return i + 1, marker // Take newline into account.
+	return i, marker
 }
 
 // fencedCodeBlock returns the end index if data contains a fenced code block at the beginning,
@@ -1133,18 +1136,22 @@ func (p *parser) listItem(out *bytes.Buffer, data []byte, flags *int) int {
 		i++
 	}
 
+	// process the following lines
+	containsBlankLine := false
+	sublist := 0
+	codeBlockMarker := ""
+	if p.flags&EXTENSION_FENCED_CODE != 0 && i > line {
+		// determine if codeblock starts on the first line
+		_, codeBlockMarker = isFenceLine(data[line:i], nil, "", false)
+	}
+
 	// get working buffer
 	var raw bytes.Buffer
 
 	// put the first line into the working buffer
 	raw.Write(data[line:i])
 	line = i
 
-	// process the following lines
-	containsBlankLine := false
-	sublist := 0
-	codeBlockMarker := ""
-
 gatherlines:
 	for line < len(data) {
 		i++
@@ -1153,7 +1160,6 @@ gatherlines:
 		for data[i-1] != '\n' {
 			i++
 		}
-
 		// if it is an empty line, guess that it is part of this item
 		// and move on to the next line
 		if p.isEmpty(data[line:i]) > 0 {

block_test.go

@@ -697,8 +697,8 @@ func TestUnorderedList(t *testing.T) {
 		"* List\n        extra indent, same paragraph\n",
 		"<ul>\n<li>List\n    extra indent, same paragraph</li>\n</ul>\n",
 
-		"* List\n\n        code block\n",
-		"<ul>\n<li><p>List</p>\n\n<pre><code>code block\n</code></pre></li>\n</ul>\n",
+		"* List\n\n        code block\n\n* List continues",
+		"<ul>\n<li><p>List</p>\n\n<pre><code>code block\n</code></pre></li>\n\n<li><p>List continues</p></li>\n</ul>\n",
 
 		"* List\n\n          code block with spaces\n",
 		"<ul>\n<li><p>List</p>\n\n<pre><code>  code block with spaces\n</code></pre></li>\n</ul>\n",
@@ -1096,7 +1096,7 @@ func TestFencedCodeBlock(t *testing.T) {
 		"<p>``` lisp\nno ending</p>\n",
 
 		"~~~ lisp\nend with language\n~~~ lisp\n",
-		"<p>~~~ lisp\nend with language\n~~~ lisp</p>\n",
+		"<pre><code class=\"language-lisp\">end with language\n</code></pre>\n\n<p>lisp</p>\n",
 
 		"```\nmismatched begin and end\n~~~\n",
 		"<p>```\nmismatched begin and end\n~~~</p>\n",
@@ -1139,6 +1139,21 @@ func TestFencedCodeBlock(t *testing.T) {
 
 		"```\n[]:()\n[]:)\n[]:(\n[]:x\n[]:testing\n[:testing\n\n[]:\nlinebreak\n[]()\n\n[]:\n[]()\n```",
 		"<pre><code>[]:()\n[]:)\n[]:(\n[]:x\n[]:testing\n[:testing\n\n[]:\nlinebreak\n[]()\n\n[]:\n[]()\n</code></pre>\n",
+
+		"- test\n\n```\n  codeblock\n  ```\ntest\n",
+		"<ul>\n<li><p>test</p>\n\n<pre><code>codeblock\n</code></pre></li>\n</ul>\n\n<p>test</p>\n",
+
+		"- ```\n  codeblock\n  ```\n\n- test\n",
+		"<ul>\n<li><pre><code>codeblock\n</code></pre></li>\n\n<li><p>test</p></li>\n</ul>\n",
+
+		"- test\n- ```\n  codeblock\n  ```\n",
+		"<ul>\n<li>test</li>\n\n<li><pre><code>codeblock\n</code></pre></li>\n</ul>\n",
+
+		"- test\n```\ncodeblock\n```\n\n- test\n",
+		"<ul>\n<li><p>test</p>\n\n<pre><code>codeblock\n</code></pre></li>\n\n<li><p>test</p></li>\n</ul>\n",
+
+		"- test\n```go\nfunc foo() bool {\n\treturn true;\n}\n```\n\n- test\n",
+		"<ul>\n<li><p>test</p>\n\n<pre><code class=\"language-go\">func foo() bool {\n\treturn true;\n}\n</code></pre></li>\n\n<li><p>test</p></li>\n</ul>\n",
 	}
 	doTestsBlock(t, tests, EXTENSION_FENCED_CODE)
 }
@@ -1557,7 +1572,7 @@ func TestFencedCodeBlock_EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK(t *testing.T) {
 		"<p>``` lisp\nno ending</p>\n",
 
 		"~~~ lisp\nend with language\n~~~ lisp\n",
-		"<p>~~~ lisp\nend with language\n~~~ lisp</p>\n",
+		"<pre><code class=\"language-lisp\">end with language\n</code></pre>\n\n<p>lisp</p>\n",
 
 		"```\nmismatched begin and end\n~~~\n",
 		"<p>```\nmismatched begin and end\n~~~</p>\n",