Fix block parsing for fenced code blocks in lists (#476)

This is a backport of the initial fix in v2 (#372).

block.go

@@ -1143,6 +1143,7 @@ func (p *parser) listItem(out *bytes.Buffer, data []byte, flags *int) int {
 	// process the following lines
 	containsBlankLine := false
 	sublist := 0
+	codeBlockMarker := ""
 
 gatherlines:
 	for line < len(data) {
@@ -1170,6 +1171,28 @@ gatherlines:
 
 		chunk := data[line+indent : i]
 
+		if p.flags&EXTENSION_FENCED_CODE != 0 {
+			// determine if in or out of codeblock
+			// if in codeblock, ignore normal list processing
+			_, marker := isFenceLine(chunk, nil, codeBlockMarker, false)
+			if marker != "" {
+				if codeBlockMarker == "" {
+					// start of codeblock
+					codeBlockMarker = marker
+				} else {
+					// end of codeblock.
+					*flags |= LIST_ITEM_CONTAINS_BLOCK
+					codeBlockMarker = ""
+				}
+			}
+			// we are in a codeblock, write line, and continue
+			if codeBlockMarker != "" || marker != "" {
+				raw.Write(data[line+indent : i])
+				line = i
+				continue gatherlines
+			}
+		}
+
 		// evaluate how this line fits in
 		switch {
 		// is this a nested list item?

block_test.go

@@ -1583,6 +1583,44 @@ func TestFencedCodeBlock_EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK(t *testing.T) {
 	doTestsBlock(t, tests, EXTENSION_FENCED_CODE|EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK)
 }
 
+func TestListWithFencedCodeBlock(t *testing.T) {
+	var tests = []string{
+		"1. one\n\n    ```\n    code\n    ```\n\n2. two\n",
+		"<ol>\n<li><p>one</p>\n\n<pre><code>code\n</code></pre></li>\n\n<li><p>two</p></li>\n</ol>\n",
+		// https://github.com/russross/blackfriday/issues/239
+		"1. one\n\n    ```\n    - code\n    ```\n\n2. two\n",
+		"<ol>\n<li><p>one</p>\n\n<pre><code>- code\n</code></pre></li>\n\n<li><p>two</p></li>\n</ol>\n",
+	}
+	doTestsBlock(t, tests, EXTENSION_FENCED_CODE)
+}
+
+func TestListWithMalformedFencedCodeBlock(t *testing.T) {
+	// Ensure that in the case of an unclosed fenced code block in a list,
+	// no source gets ommitted (even if it is malformed).
+	// See russross/blackfriday#372 for context.
+	var tests = []string{
+		"1. one\n\n    ```\n    code\n\n2. two\n",
+		"<ol>\n<li>one\n\n```\ncode\n\n2. two</li>\n</ol>\n",
+
+		"1. one\n\n    ```\n    - code\n\n2. two\n",
+		"<ol>\n<li>one\n\n```\n- code\n\n2. two</li>\n</ol>\n",
+	}
+	doTestsBlock(t, tests, EXTENSION_FENCED_CODE)
+}
+
+func TestListWithFencedCodeBlockNoExtensions(t *testing.T) {
+	// If there is a fenced code block in a list, and FencedCode is not set,
+	// lists should be processed normally.
+	var tests = []string{
+		"1. one\n\n    ```\n    code\n    ```\n\n2. two\n",
+		"<ol>\n<li><p>one</p>\n\n<p><code>\ncode\n</code></p></li>\n\n<li><p>two</p></li>\n</ol>\n",
+
+		"1. one\n\n    ```\n    - code\n    ```\n\n2. two\n",
+		"<ol>\n<li><p>one</p>\n\n<p>```</p>\n\n<ul>\n<li>code\n```</li>\n</ul></li>\n\n<li><p>two</p></li>\n</ol>\n",
+	}
+	doTestsBlock(t, tests, 0)
+}
+
 func TestTitleBlock_EXTENSION_TITLEBLOCK(t *testing.T) {
 	var tests = []string{
 		"% Some title\n" +