Add sync-group-id support

Closes gh-21

Author: rwinch

lib/include-code-extension.js

@@ -47,7 +47,7 @@ function createExtensionGroup (context) {
           return accum.concat({ name, lang, lines })
         }, [])
         if (!includes.length) return log(doc, 'warn', `no code includes found for ${target}`)
-        const tabsSource = generateTabsSource(attrs.title, includes, tabsEnabled)
+        const tabsSource = generateTabsSource(attrs.title, attrs['sync-group-id'], includes, tabsEnabled)
         const reader = PreprocessorReader.$new(doc, tabsSource, cursor)
         Object.defineProperty(reader, 'lineno', { get: () => cursor.lineno })
         return this.parseContent(parent, reader)
@@ -56,16 +56,17 @@ function createExtensionGroup (context) {
   }
 }
 
-function generateTabsSource (title, includes, tabsEnabled) {
+function generateTabsSource (title, syncGroupId, includes, tabsEnabled) {
   const source = []
   if (includes.length === 1) {
     if (title) source.push('.' + title)
     source.push(`[,${includes[0].lang}]`, '----', ...includes[0].lines, '----')
   } else if (tabsEnabled) {
     if (title) source.push('.' + title)
     const lastIdx = includes.length - 1
+    const tabAttrs = syncGroupId ? `,sync-group-id=${syncGroupId}` : ''
     includes.forEach(({ name, lang, lines }, idx) => {
-      idx ? source.push('') : source.push('[tabs]', '======')
+      idx ? source.push('') : source.push(`[tabs${tabAttrs}]`, '======')
       source.push(`${name}::`, '+', `[,${lang}]`, '----', ...lines, '----')
       if (idx === lastIdx) source.push('======')
     })

test/include-code-extension-test.js

@@ -281,6 +281,66 @@ describe('include-code-extension', () => {
       expect(actual.getBlocks()[0].getAttributes()).to.include(expectedAttrs)
     })
 
+    it('should support sync-group-id', () => {
+      addExample(
+        'kotlin/hello.kt',
+        heredoc`
+        fun main(args : Array<String>) {
+          println("Hello, World!")
+        }
+        `
+      )
+      addExample(
+        'java/hello.java',
+        heredoc`
+        public class Hello {
+          public static void main (String[] args) {
+            System.out.println("Hello, World!");
+          }
+        }
+        `
+      )
+      const input = heredoc`
+      = Test
+      :tabs-sync-option:
+
+      include-code::hello[sync-group-id=thisisauniqueid]
+      `
+      const actual = run(input, { registerAsciidoctorTabs: true })
+      expect(actual.convert()).to.contain(
+        'class="openblock tabs is-sync data-sync-group-id=thisisauniqueid is-loading"'
+      )
+    })
+
+    it('should support sync-group-id not defined', () => {
+      addExample(
+        'kotlin/hello.kt',
+        heredoc`
+        fun main(args : Array<String>) {
+          println("Hello, World!")
+        }
+        `
+      )
+      addExample(
+        'java/hello.java',
+        heredoc`
+        public class Hello {
+          public static void main (String[] args) {
+            System.out.println("Hello, World!");
+          }
+        }
+        `
+      )
+      const input = heredoc`
+      = Test
+      :tabs-sync-option:
+
+      include-code::hello[]
+      `
+      const actual = run(input, { registerAsciidoctorTabs: true })
+      expect(actual.convert()).to.contain('class="openblock tabs is-sync is-loading"')
+    })
+
     it('should report line number of block macro when include tag not found', () => {
       const inputSource = heredoc`
       fun main(args : Array<String>) {