Add Goldmark as the new default markdown handler

This commit adds the fast and CommonMark compliant Goldmark as the new default markdown handler in Hugo.

If you want to continue using BlackFriday as the default for md/markdown extensions, you can use this configuration:

```toml
[markup]
defaultMarkdownHandler="blackfriday"
```

Fixes #5963
Fixes #1778
Fixes #6355

1 files changed, 219 insertions, 0 deletions

diff --git a/markup/goldmark/convert_test.go b/markup/goldmark/convert_test.go
new file mode 100644
index 000000000..47798660d
--- /dev/null
+++ b/markup/goldmark/convert_test.go
@@ -0,0 +1,219 @@
+// Copyright 2019 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package goldmark
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/gohugoio/hugo/markup/highlight"
+
+	"github.com/gohugoio/hugo/markup/markup_config"
+
+	"github.com/gohugoio/hugo/common/loggers"
+
+	"github.com/gohugoio/hugo/markup/converter"
+
+	qt "github.com/frankban/quicktest"
+)
+
+func TestConvert(t *testing.T) {
+	c := qt.New(t)
+
+	// Smoke test of the default configuration.
+	content := `
+## Code Fences
+
+§§§bash
+LINE1
+§§§
+
+## Code Fences No Lexer
+
+§§§moo
+LINE1
+§§§
+
+## Custom ID {#custom}
+
+## Auto ID
+
+* Autolink: https://gohugo.io/
+* Strikethrough:~~Hi~~ Hello, world!
+ 
+## Table
+
+| foo | bar |
+| --- | --- |
+| baz | bim |
+
+## Task Lists (default on)
+
+- [x] Finish my changes[^1]
+- [ ] Push my commits to GitHub
+- [ ] Open a pull request
+
+
+## Smartypants (default on)
+
+* Straight double "quotes" and single 'quotes' into “curly” quote HTML entities
+* Dashes (“--” and “---”) into en- and em-dash entities
+* Three consecutive dots (“...”) into an ellipsis entity
+
+## Footnotes
+
+That's some text with a footnote.[^1]
+
+## Definition Lists
+
+date
+: the datetime assigned to this page. 
+
+description
+: the description for the content.
+
+
+[^1]: And that's the footnote.
+
+`
+
+	// Code fences
+	content = strings.Replace(content, "§§§", "```", -1)
+
+	mconf := markup_config.Default
+	mconf.Highlight.NoClasses = false
+
+	p, err := Provider.New(
+		converter.ProviderConfig{
+			MarkupConfig: mconf,
+			Logger:       loggers.NewErrorLogger(),
+		},
+	)
+	c.Assert(err, qt.IsNil)
+	conv, err := p.New(converter.DocumentContext{})
+	c.Assert(err, qt.IsNil)
+	b, err := conv.Convert(converter.RenderContext{Src: []byte(content)})
+	c.Assert(err, qt.IsNil)
+
+	got := string(b.Bytes())
+
+	// Header IDs
+	c.Assert(got, qt.Contains, `<h2 id="custom">Custom ID</h2>`, qt.Commentf(got))
+	c.Assert(got, qt.Contains, `<h2 id="auto-id">Auto ID</h2>`, qt.Commentf(got))
+
+	// Code fences
+	c.Assert(got, qt.Contains, "<div class=\"highlight\"><pre class=\"chroma\"><code class=\"language-bash\" data-lang=\"bash\">LINE1\n</code></pre></div>")
+	c.Assert(got, qt.Contains, "Code Fences No Lexer</h2>\n<pre><code class=\"language-moo\" data-lang=\"moo\">LINE1\n</code></pre>")
+
+	// Extensions
+	c.Assert(got, qt.Contains, `Autolink: <a href="https://gohugo.io/">https://gohugo.io/</a>`)
+	c.Assert(got, qt.Contains, `Strikethrough:<del>Hi</del> Hello, world`)
+	c.Assert(got, qt.Contains, `<th>foo</th>`)
+	c.Assert(got, qt.Contains, `<li><input disabled="" type="checkbox">Push my commits to GitHub</li>`)
+
+	c.Assert(got, qt.Contains, `Straight double &ldquo;quotes&rdquo; and single &lsquo;quotes&rsquo;`)
+	c.Assert(got, qt.Contains, `Dashes (“&ndash;” and “&mdash;”) `)
+	c.Assert(got, qt.Contains, `Three consecutive dots (“&hellip;”)`)
+	c.Assert(got, qt.Contains, `footnote.<sup id="fnref:1"><a href="#fn:1" class="footnote-ref" role="doc-noteref">1</a></sup>`)
+	c.Assert(got, qt.Contains, `<section class="footnotes" role="doc-endnotes">`)
+	c.Assert(got, qt.Contains, `<dt>date</dt>`)
+
+}
+
+func TestCodeFence(t *testing.T) {
+	c := qt.New(t)
+
+	lines := `LINE1
+LINE2
+LINE3
+LINE4
+LINE5
+`
+
+	convertForConfig := func(c *qt.C, conf highlight.Config, code, language string) string {
+		mconf := markup_config.Default
+		mconf.Highlight = conf
+
+		p, err := Provider.New(
+			converter.ProviderConfig{
+				MarkupConfig: mconf,
+				Logger:       loggers.NewErrorLogger(),
+			},
+		)
+
+		content := "```" + language + "\n" + code + "\n```"
+
+		c.Assert(err, qt.IsNil)
+		conv, err := p.New(converter.DocumentContext{})
+		c.Assert(err, qt.IsNil)
+		b, err := conv.Convert(converter.RenderContext{Src: []byte(content)})
+		c.Assert(err, qt.IsNil)
+
+		return string(b.Bytes())
+	}
+
+	c.Run("Basic", func(c *qt.C) {
+		cfg := highlight.DefaultConfig
+		cfg.NoClasses = false
+
+		result := convertForConfig(c, cfg, `echo "Hugo Rocks!"`, "bash")
+		// TODO(bep) there is a whitespace mismatch (\n) between this and the highlight template func.
+		c.Assert(result, qt.Equals, `<div class="highlight"><pre class="chroma"><code class="language-bash" data-lang="bash"><span class="nb">echo</span> <span class="s2">&#34;Hugo Rocks!&#34;</span>
+</code></pre></div>`)
+		result = convertForConfig(c, cfg, `echo "Hugo Rocks!"`, "unknown")
+		c.Assert(result, qt.Equals, "<pre><code class=\"language-unknown\" data-lang=\"unknown\">echo &quot;Hugo Rocks!&quot;\n</code></pre>")
+
+	})
+
+	c.Run("Highlight lines, default config", func(c *qt.C) {
+		cfg := highlight.DefaultConfig
+		cfg.NoClasses = false
+
+		result := convertForConfig(c, cfg, lines, `bash {linenos=table,hl_lines=[2 "4-5"],linenostart=3}`)
+		c.Assert(result, qt.Contains, "<div class=\"highlight\"><div class=\"chroma\">\n<table class=\"lntable\"><tr><td class=\"lntd\">\n<pre class=\"chroma\"><code><span class")
+		c.Assert(result, qt.Contains, "<span class=\"hl\"><span class=\"lnt\">4")
+
+		result = convertForConfig(c, cfg, lines, "bash {linenos=inline,hl_lines=[2]}")
+		c.Assert(result, qt.Contains, "<span class=\"ln\">2</span>LINE2\n</span>")
+		c.Assert(result, qt.Not(qt.Contains), "<table")
+
+		result = convertForConfig(c, cfg, lines, "bash {linenos=true,hl_lines=[2]}")
+		c.Assert(result, qt.Contains, "<table")
+		c.Assert(result, qt.Contains, "<span class=\"hl\"><span class=\"lnt\">2\n</span>")
+	})
+
+	c.Run("Highlight lines, linenumbers default on", func(c *qt.C) {
+		cfg := highlight.DefaultConfig
+		cfg.NoClasses = false
+		cfg.LineNos = true
+
+		result := convertForConfig(c, cfg, lines, "bash")
+		c.Assert(result, qt.Contains, "<span class=\"lnt\">2\n</span>")
+
+		result = convertForConfig(c, cfg, lines, "bash {linenos=false,hl_lines=[2]}")
+		c.Assert(result, qt.Not(qt.Contains), "class=\"lnt\"")
+	})
+
+	c.Run("Highlight lines, linenumbers default on, linenumbers in table default off", func(c *qt.C) {
+		cfg := highlight.DefaultConfig
+		cfg.NoClasses = false
+		cfg.LineNos = true
+		cfg.LineNumbersInTable = false
+
+		result := convertForConfig(c, cfg, lines, "bash")
+		c.Assert(result, qt.Contains, "<span class=\"ln\">2</span>LINE2\n<")
+		result = convertForConfig(c, cfg, lines, "bash {linenos=table}")
+		c.Assert(result, qt.Contains, "<span class=\"lnt\">1\n</span>")
+	})
+}