Fix escaping in post summary

Unescaping post content after sanitizing it. This will prevent double
escaping when summary is rendered by html/template package which does
escaping by default.
Fixes #340

postrender.go

@@ -140,9 +140,7 @@ func applyBasicMarkdown(data []byte) string {
 func postTitle(content, friendlyId string) string {
 	const maxTitleLen = 80
 
-	// Strip HTML tags with bluemonday's StrictPolicy, then unescape the HTML
-	// entities added in by sanitizing the content.
-	content = html.UnescapeString(bluemonday.StrictPolicy().Sanitize(content))
+	content = stripHTMLWithoutEscaping(content)
 
 	content = strings.TrimLeftFunc(stripmd.Strip(content), unicode.IsSpace)
 	eol := strings.IndexRune(content, '\n')
@@ -160,9 +158,7 @@ func postTitle(content, friendlyId string) string {
 func friendlyPostTitle(content, friendlyId string) string {
 	const maxTitleLen = 80
 
-	// Strip HTML tags with bluemonday's StrictPolicy, then unescape the HTML
-	// entities added in by sanitizing the content.
-	content = html.UnescapeString(bluemonday.StrictPolicy().Sanitize(content))
+	content = stripHTMLWithoutEscaping(content)
 
 	content = strings.TrimLeftFunc(stripmd.Strip(content), unicode.IsSpace)
 	eol := strings.IndexRune(content, '\n')
@@ -179,6 +175,12 @@ func friendlyPostTitle(content, friendlyId string) string {
 	return title
 }
 
+// Strip HTML tags with bluemonday's StrictPolicy, then unescape the HTML
+// entities added in by sanitizing the content.
+func stripHTMLWithoutEscaping(content string) string {
+	return html.UnescapeString(bluemonday.StrictPolicy().Sanitize(content))
+}
+
 func getSanitizationPolicy() *bluemonday.Policy {
 	policy := bluemonday.UGCPolicy()
 	policy.AllowAttrs("src", "style").OnElements("iframe", "video", "audio")

posts.go

@@ -211,8 +211,7 @@ func (p Post) Summary() string {
 	if p.Content == "" {
 		return ""
 	}
-	// Strip out HTML
-	p.Content = bluemonday.StrictPolicy().Sanitize(p.Content)
+	p.Content = stripHTMLWithoutEscaping(p.Content)
 	// and Markdown
 	p.Content = stripmd.Strip(p.Content)
 

posts_test.go

@@ -0,0 +1,35 @@
+package writefreely_test
+
+import (
+	"testing"
+
+	"github.com/guregu/null/zero"
+	"github.com/stretchr/testify/assert"
+	"github.com/writeas/writefreely"
+)
+
+func TestPostSummary(t *testing.T) {
+	testCases := map[string]struct {
+		given    writefreely.Post
+		expected string
+	}{
+		"no special chars":          {givenPost("Content."), "Content."},
+		"HTML content":              {givenPost("Content <p>with a</p> paragraph."), "Content with a paragraph."},
+		"content with escaped char": {givenPost("Content&#39;s all OK."), "Content's all OK."},
+		"multiline content": {givenPost(`Content
+in
+multiple
+lines.`), "Content in multiple lines."},
+	}
+
+	for name, test := range testCases {
+		t.Run(name, func(t *testing.T) {
+			actual := test.given.Summary()
+			assert.Equal(t, test.expected, actual)
+		})
+	}
+}
+
+func givenPost(content string) writefreely.Post {
+	return writefreely.Post{Title: zero.StringFrom("Title"), Content: content}
+}