fix: strip line break added by gray matter

decaporg · Feb 27, 2020 · 8c6a78e · 8c6a78e
1 parent 5992b4a
commit 8c6a78e
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Showing 2 changed files with 33 additions and 10 deletions.
diff --git a/packages/netlify-cms-core/src/formats/__tests__/frontmatter.spec.js b/packages/netlify-cms-core/src/formats/__tests__/frontmatter.spec.js
@@ -179,14 +179,14 @@ describe('Frontmatter', () => {
         'title: YAML',
         '---',
         'Some content',
-        'On another line\n',
+        'On another line',
       ].join('\n'),
     );
   });
 
   it('should stringify YAML with missing body', () => {
     expect(FrontmatterInfer.toFile({ tags: ['front matter', 'yaml'], title: 'YAML' })).toEqual(
-      ['---', 'tags:', '  - front matter', '  - yaml', 'title: YAML', '---', '', ''].join('\n'),
+      ['---', 'tags:', '  - front matter', '  - yaml', 'title: YAML', '---', ''].join('\n'),
     );
   });
 
@@ -206,7 +206,7 @@ describe('Frontmatter', () => {
         'title: YAML',
         '---',
         'Some content',
-        'On another line\n',
+        'On another line',
       ].join('\n'),
     );
   });
@@ -227,7 +227,7 @@ describe('Frontmatter', () => {
         'title: YAML',
         '~~~',
         'Some content',
-        'On another line\n',
+        'On another line',
       ].join('\n'),
     );
   });
@@ -248,7 +248,7 @@ describe('Frontmatter', () => {
         'title: YAML',
         '^^^',
         'Some content',
-        'On another line\n',
+        'On another line',
       ].join('\n'),
     );
   });
@@ -267,7 +267,7 @@ describe('Frontmatter', () => {
         'title = "TOML"',
         '+++',
         'Some content',
-        'On another line\n',
+        'On another line',
       ].join('\n'),
     );
   });
@@ -286,7 +286,7 @@ describe('Frontmatter', () => {
         'title = "TOML"',
         '~~~',
         'Some content',
-        'On another line\n',
+        'On another line',
       ].join('\n'),
     );
   });
@@ -308,7 +308,7 @@ describe('Frontmatter', () => {
         '  "title": "JSON"',
         '}',
         'Some content',
-        'On another line\n',
+        'On another line',
       ].join('\n'),
     );
   });
@@ -330,8 +330,24 @@ describe('Frontmatter', () => {
         '  "title": "JSON"',
         '~~~',
         'Some content',
-        'On another line\n',
+        'On another line',
       ].join('\n'),
     );
   });
+
+  it('should trim last line break if added by grey-matter', () => {
+    expect(
+      frontmatterYAML().toFile({
+        body: 'noLineBreak',
+      }),
+    ).toEqual('noLineBreak');
+  });
+
+  it('should not trim last line break if not added by grey-matter', () => {
+    expect(
+      frontmatterYAML().toFile({
+        body: 'withLineBreak\n',
+      }),
+    ).toEqual('withLineBreak\n');
+  });
 });
diff --git a/packages/netlify-cms-core/src/formats/frontmatter.js b/packages/netlify-cms-core/src/formats/frontmatter.js
@@ -70,6 +70,8 @@ class FrontmatterFormatter {
     const format = this.format || inferFrontmatterFormat(content);
     if (this.customDelimiter) this.format.delimiters = this.customDelimiter;
     const result = matter(content, { engines: parsers, ...format });
+    // in the absent of a body when serializing an entry we use an empty one
+    // when calling `toFile`, so we don't want to add it when parsing.
     return {
       ...result.data,
       ...(result.content.trim() && { body: result.content }),
@@ -83,8 +85,13 @@ class FrontmatterFormatter {
     const format = this.format || getFormatOpts('yaml');
     if (this.customDelimiter) this.format.delimiters = this.customDelimiter;
 
+    // gray-matter always adds a line break at the end which trips our
+    // change detection logic
+    // https://github.com/jonschlinkert/gray-matter/issues/96
+    const trimLastLineBreak = body.slice(-1) !== '\n' ? true : false;
     // `sortedKeys` is not recognized by gray-matter, so it gets passed through to the parser
-    return matter.stringify(body, meta, { engines: parsers, sortedKeys, ...format });
+    const file = matter.stringify(body, meta, { engines: parsers, sortedKeys, ...format });
+    return trimLastLineBreak && file.slice(-1) === '\n' ? file.substring(0, file.length - 1) : file;
   }
 }