Merge branch 'fix-git-blame-syntax-highlighting' into 'master'

Fix git blame syntax highlighting when different commits break up lines

### What does this MR do?

This MR fixes a bug where syntax highlighting would not work properly in certain lines when doing a `git blame` view of a file. Also, this MR reuses the Rugments lexer and formatter for each `git blame` commit block, which should make things faster and reduce overhead.

### Why was this MR needed?

When doing a `git blame`, GitLab feeds the Rugments lexer/formatter blocks of code based on the latest commit for each line.  However, this can cause lexer to fail because the state is cleared between each block of code, which causes `highlight` to fallback to the plaintext lexer. For example, notice this unhighlighted line in [this file](https://gitlab.common-lisp.net/cmucl/cmucl/blame/master/src/assembly/assemfile.lisp):

![image](https://gitlab.com/gitlab-org/gitlab-ce/uploads/b403fe5c2b883882a9eeea7e0409c583/image.png)

The fixed version looks like this:

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/32c4d7c8ff15a7d59b364dd988f7c657/image.png)

This MR requires a patch to rugments to allow the `continue` option to be passed to the lexer.

* https://github.com/rumpelsepp/rugments/pull/24
* https://github.com/rumpelsepp/rugments/pull/23
* Also submitted to rouge: https://github.com/jneen/rouge/pull/267

### What are the relevant issue numbers?

Closes #1521

See merge request !697

1 files changed, 33 insertions, 0 deletions

diff --git a/spec/helpers/blob_helper_spec.rb b/spec/helpers/blob_helper_spec.rb
new file mode 100644
index 00000000000..e49e4e6d5d8
--- /dev/null
+++ b/spec/helpers/blob_helper_spec.rb
@@ -0,0 +1,33 @@
+require 'spec_helper'
+
+describe BlobHelper do
+  describe 'highlight' do
+    let(:blob_name) { 'test.lisp' }
+    let(:no_context_content) { ":type \"assem\"))" }
+    let(:blob_content) { "(make-pathname :defaults name\n#{no_context_content}" }
+    let(:split_content) { blob_content.split("\n") }
+
+    it 'should return plaintext for unknown lexer context' do
+      result = highlight(blob_name, no_context_content, nowrap: true, continue: false)
+      expect(result).to eq('<span id="LC1" class="line">:type &quot;assem&quot;))</span>')
+    end
+
+    it 'should highlight single block' do
+      expected = %Q[<span id="LC1" class="line"><span class="p">(</span><span class="nb">make-pathname</span> <span class="ss">:defaults</span> <span class="nv">name</span></span>
+<span id="LC2" class="line"><span class="ss">:type</span> <span class="s">&quot;assem&quot;</span><span class="p">))</span></span>]
+
+      expect(highlight(blob_name, blob_content, nowrap: true, continue: false)).to eq(expected)
+    end
+
+    it 'should highlight continued blocks' do
+      # Both lines have LC1 as ID since formatter doesn't support continue at the moment
+      expected = [
+        '<span id="LC1" class="line"><span class="p">(</span><span class="nb">make-pathname</span> <span class="ss">:defaults</span> <span class="nv">name</span></span>',
+        '<span id="LC1" class="line"><span class="ss">:type</span> <span class="s">&quot;assem&quot;</span><span class="p">))</span></span>'
+      ]
+
+      result = split_content.map{ |content| highlight(blob_name, content, nowrap: true, continue: true) }
+      expect(result).to eq(expected)
+    end
+  end
+end