Make sure relative URLs are preserved

Add tests to make sure we don't break relative URLs again.
Extracted common html flags and common extensions for easy access from
tests.

Closes issue #104, which was fixed as a side effect of cf6bfc9.

inline_test.go

@@ -42,6 +42,7 @@ func doLinkTestsInline(t *testing.T, tests []string) {
 	params := HtmlRendererParameters{AbsolutePrefix: prefix}
 	transformTests := transformLinks(tests, prefix)
 	doTestsInlineParam(t, transformTests, 0, 0, params)
+	doTestsInlineParam(t, transformTests, 0, commonHtmlFlags(), params)
 }
 
 func doSafeTestsInline(t *testing.T, tests []string) {
@@ -354,6 +355,12 @@ func TestInlineLink(t *testing.T) {
 		"![foo with a title](/bar/ title with no quotes)\n",
 		"<p><img src=\"/bar/ title with no quotes\" alt=\"foo with a title\" />\n</p>\n",
 
+		"![](img.jpg)\n",
+		"<p><img src=\"img.jpg\" alt=\"\" />\n</p>\n",
+
+		"[link](url)\n",
+		"<p><a href=\"url\">link</a></p>\n",
+
 		"![foo]()\n",
 		"<p>![foo]()</p>\n",
 

markdown.go

@@ -212,6 +212,27 @@ func MarkdownBasic(input []byte) []byte {
 	return Markdown(input, renderer, extensions)
 }
 
+func commonHtmlFlags() int {
+	htmlFlags := 0
+	htmlFlags |= HTML_USE_XHTML
+	htmlFlags |= HTML_USE_SMARTYPANTS
+	htmlFlags |= HTML_SMARTYPANTS_FRACTIONS
+	htmlFlags |= HTML_SMARTYPANTS_LATEX_DASHES
+	return htmlFlags
+}
+
+func commonExtensions() int {
+	extensions := 0
+	extensions |= EXTENSION_NO_INTRA_EMPHASIS
+	extensions |= EXTENSION_TABLES
+	extensions |= EXTENSION_FENCED_CODE
+	extensions |= EXTENSION_AUTOLINK
+	extensions |= EXTENSION_STRIKETHROUGH
+	extensions |= EXTENSION_SPACE_HEADERS
+	extensions |= EXTENSION_HEADER_IDS
+	return extensions
+}
+
 // Call Markdown with most useful extensions enabled
 // MarkdownCommon is a convenience function for simple rendering.
 // It processes markdown input with common extensions enabled, including:
@@ -233,24 +254,8 @@ func MarkdownBasic(input []byte) []byte {
 // * Custom Header IDs
 func MarkdownCommon(input []byte) []byte {
 	// set up the HTML renderer
-	htmlFlags := 0
-	htmlFlags |= HTML_USE_XHTML
-	htmlFlags |= HTML_USE_SMARTYPANTS
-	htmlFlags |= HTML_SMARTYPANTS_FRACTIONS
-	htmlFlags |= HTML_SMARTYPANTS_LATEX_DASHES
-	renderer := HtmlRenderer(htmlFlags, "", "")
-
-	// set up the parser
-	extensions := 0
-	extensions |= EXTENSION_NO_INTRA_EMPHASIS
-	extensions |= EXTENSION_TABLES
-	extensions |= EXTENSION_FENCED_CODE
-	extensions |= EXTENSION_AUTOLINK
-	extensions |= EXTENSION_STRIKETHROUGH
-	extensions |= EXTENSION_SPACE_HEADERS
-	extensions |= EXTENSION_HEADER_IDS
-
-	return Markdown(input, renderer, extensions)
+	renderer := HtmlRenderer(commonHtmlFlags(), "", "")
+	return Markdown(input, renderer, commonExtensions())
 }
 
 // Markdown is the main rendering function.