Extract blog post truncation logic and add tests (#640)

lib/core/BlogPost.js

@@ -8,32 +8,32 @@
 const MarkdownBlock = require('./MarkdownBlock.js');
 const React = require('react');
 
+const utils = require('./utils');
+
 // inner blog component for the article itself, without sidebar/header/footer
 class BlogPost extends React.Component {
   renderContent() {
-    let content = this.props.content;
-    let hasSplit = false;
-    if (content.split('<!--truncate-->').length > 1) {
-      hasSplit = (
-        <div className="read-more">
-          <a
-            className="button"
-            href={this.props.config.baseUrl + 'blog/' + this.props.post.path}>
-            Read More
-          </a>
-        </div>
-      );
-    }
     if (this.props.truncate) {
-      content = content.split('<!--truncate-->')[0];
       return (
         <article className="post-content">
-          <MarkdownBlock>{content}</MarkdownBlock>
+          <MarkdownBlock>
-          {hasSplit}
+            {utils.extractBlogPostBeforeTruncate(this.props.content)}
+          </MarkdownBlock>
+          {utils.blogPostHasTruncateMarker(this.props.content) && (
+            <div className="read-more">
+              <a
+                className="button"
+                href={
+                  this.props.config.baseUrl + 'blog/' + this.props.post.path
+                }>
+                Read More
+              </a>
+            </div>
+          )}
         </article>
       );
     }
-    return <MarkdownBlock>{content}</MarkdownBlock>;
+    return <MarkdownBlock>{this.props.content}</MarkdownBlock>;
   }
 
   renderAuthorPhoto() {

lib/core/__tests__/__fixtures__/blog-post-with-truncate.md

@@ -0,0 +1,15 @@
+---
+title: Truncation Example
+---
+
+All this will be part of the blog post summary.
+
+Even this.
+
+<!--truncate-->
+
+But anything from here on down will not be.
+
+Not this.
+
+Or this.

lib/core/__tests__/__fixtures__/blog-post-without-truncate.md

@@ -0,0 +1,13 @@
+---
+title: Non-truncation Example
+---
+
+All this will be part of the blog post summary.
+
+Even this.
+
+And anything from here on down will still be.
+
+And this.
+
+And this too.

lib/core/__tests__/__snapshots__/utils.test.js.snap

@@ -0,0 +1,66 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`utils extractBlogPostBeforeTruncate 1`] = `
+"---
+title: Truncation Example
+---
+
+All this will be part of the blog post summary.
+
+Even this.
+
+"
+`;
+
+exports[`utils extractBlogPostBeforeTruncate 2`] = `
+"---
+title: Non-truncation Example
+---
+
+All this will be part of the blog post summary.
+
+Even this.
+
+And anything from here on down will still be.
+
+And this.
+
+And this too.
+"
+`;
+
+exports[`utils extractBlogPostSummary 1`] = `
+"---
+title: Truncation Example
+---
+
+All this will be part of the blog post summary.
+
+Even this.
+
+<!--truncate-->
+
+But anything from here on down will not be.
+
+Not this.
+
+Or this.
+"
+`;
+
+exports[`utils extractBlogPostSummary 2`] = `
+"---
+title: Non-truncation Example
+---
+
+All this will be part of the blog post summary.
+
+Even this.
+
+And anything from here on down will still be.
+
+And this.
+
+And this too.
+"
+`;

lib/core/__tests__/utils.test.js

@@ -0,0 +1,49 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const path = require('path');
+const utils = require('../utils');
+const readFileSync = require('fs').readFileSync;
+
+const blogPostWithTruncateContents = readFileSync(
+  path.join(__dirname, '__fixtures__', 'blog-post-with-truncate.md'),
+  'utf-8'
+);
+
+const blogPostWithoutTruncateContents = readFileSync(
+  path.join(__dirname, '__fixtures__', 'blog-post-without-truncate.md'),
+  'utf-8'
+);
+
+describe('utils', () => {
+  test('blogPostHasTruncateMarker', () => {
+    expect(utils.blogPostHasTruncateMarker(blogPostWithTruncateContents)).toBe(
+      true
+    );
+    expect(
+      utils.blogPostHasTruncateMarker(blogPostWithoutTruncateContents)
+    ).toBe(false);
+  });
+
+  test('extractBlogPostBeforeTruncate', () => {
+    expect(
+      utils.extractBlogPostBeforeTruncate(blogPostWithTruncateContents)
+    ).toMatchSnapshot();
+    expect(
+      utils.extractBlogPostBeforeTruncate(blogPostWithoutTruncateContents)
+    ).toMatchSnapshot();
+  });
+
+  test('extractBlogPostSummary', () => {
+    expect(
+      utils.extractBlogPostSummary(blogPostWithTruncateContents)
+    ).toMatchSnapshot();
+    expect(
+      utils.extractBlogPostSummary(blogPostWithoutTruncateContents)
+    ).toMatchSnapshot();
+  });
+});

lib/core/utils.js

@@ -0,0 +1,27 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const BLOG_POST_SUMMARY_LENGTH = 250;
+const TRUNCATE_MARKER = /<!--\s*truncate\s*-->/;
+
+function blogPostHasTruncateMarker(content) {
+  return TRUNCATE_MARKER.test(content);
+}
+
+function extractBlogPostBeforeTruncate(content) {
+  return content.split(TRUNCATE_MARKER)[0];
+}
+
+function extractBlogPostSummary(content) {
+  return content.substring(0, BLOG_POST_SUMMARY_LENGTH);
+}
+
+module.exports = {
+  blogPostHasTruncateMarker,
+  extractBlogPostBeforeTruncate,
+  extractBlogPostSummary,
+};

lib/server/feed.js

@@ -19,6 +19,7 @@ const blogFolder = path.resolve('../blog/');
 const blogRootURL = siteConfig.url + siteConfig.baseUrl + 'blog';
 const siteImageURL =
   siteConfig.url + siteConfig.baseUrl + siteConfig.headerIcon;
+const utils = require('../core/utils');
 
 const renderMarkdown = require('../core/renderMarkdown.js');
 
@@ -56,18 +57,9 @@ module.exports = function(type) {
 
   MetadataBlog.forEach(post => {
     const url = blogRootURL + '/' + post.path;
-    let content = '';
+    const content = utils.blogPostHasTruncateMarker(post.content)
-    if (post.content.indexOf('<!--truncate-->') == -1) {
+      ? utils.extractBlogPostBeforeTruncate(post.content)
-      content = post.content.trim().substring(0, 250);
+      : utils.extractBlogPostSummary(post.content.trim());
-    } else {
-      let contentArr = post.content.split('<!--truncate-->');
-      if (contentArr.length > 0) {
-        content = contentArr[0];
-      }
-    }
-
-    content = renderMarkdown(content);
-
     feed.addItem({
       title: post.title,
       link: url,
@@ -78,7 +70,7 @@ module.exports = function(type) {
         },
       ],
       date: new Date(post.date),
-      description: content,
+      description: renderMarkdown(content),
     });
   });