fix(gatsby-remark-prismjs): Update warnings to handle missing language (#13159)

* fix: Update warnings to handle missing language

* Reverted change to class and added argument to control warnings

* Keep option name consistent

Author: ojeytonwilliams

packages/gatsby-remark-prismjs/src/__tests__/highlight-code.js

@@ -56,15 +56,30 @@ export default Counter
   })
 
   describe(`with language-text`, () => {
-    it(`escapes &, <, " elements #4597 and warns`, () => {
+    it(`escapes &, <, " elements and warns`, () => {
+      spyOn(console, `warn`)
+
+      const highlightCode = require(`../highlight-code`)
+      const language = `text`
+      const code = `<button />`
+      expect(highlightCode(language, code, [], true)).toMatch(
+        `&lt;button /&gt;`
+      )
+      expect(console.warn).toHaveBeenCalledWith(
+        `code block language not specified in markdown.`,
+        `applying generic code block`
+      )
+    })
+
+    it(`can warn about languages missing from inline code`, () => {
       spyOn(console, `warn`)
 
       const highlightCode = require(`../highlight-code`)
       const language = `text`
       const code = `<button />`
       expect(highlightCode(language, code)).toMatch(`&lt;button /&gt;`)
       expect(console.warn).toHaveBeenCalledWith(
-        `unable to find prism language 'text' for highlighting.`,
+        `code block or inline code language not specified in markdown.`,
         `applying generic code block`
       )
     })
@@ -84,7 +99,7 @@ export default Counter
       expect(console.warn).toHaveBeenCalledTimes(2)
       expect(console.warn).toHaveBeenNthCalledWith(
         1,
-        `unable to find prism language 'text' for highlighting.`,
+        `code block or inline code language not specified in markdown.`,
         `applying generic code block`
       )
       expect(console.warn).toHaveBeenNthCalledWith(

packages/gatsby-remark-prismjs/src/__tests__/index.js

@@ -1,7 +1,12 @@
 const remark = require(`remark`)
-const plugin = require(`../index`)
+let plugin
 
 describe(`remark prism plugin`, () => {
+  beforeEach(() => {
+    jest.resetModules()
+    plugin = require(`../index`)
+  })
+
   describe(`generates a <pre> tag`, () => {
     it(`with class="language-*" prefix by default`, () => {
       const code = `\`\`\`js\n// Fake\n\`\`\``
@@ -101,4 +106,28 @@ describe(`remark prism plugin`, () => {
       expect(markdownAST).toMatchSnapshot()
     })
   })
+
+  describe(`warnings`, () => {
+    it(`warns if the language is not specified for a code block`, () => {
+      spyOn(console, `warn`)
+      const code = `\`\`\`\n// Fake\n\`\`\``
+      const markdownAST = remark.parse(code)
+      plugin({ markdownAST }, { noInlineHighlight: true })
+      expect(console.warn).toHaveBeenCalledWith(
+        `code block language not specified in markdown.`,
+        `applying generic code block`
+      )
+    })
+
+    it(`gives a different warning if inline code can be highlighted`, () => {
+      spyOn(console, `warn`)
+      const code = `\`foo bar\``
+      const markdownAST = remark.parse(code)
+      plugin({ markdownAST })
+      expect(console.warn).toHaveBeenCalledWith(
+        `code block or inline code language not specified in markdown.`,
+        `applying generic code block`
+      )
+    })
+  })
 })

packages/gatsby-remark-prismjs/src/highlight-code.js

@@ -5,26 +5,37 @@ const loadPrismLanguage = require(`./load-prism-language`)
 const handleDirectives = require(`./directives`)
 const unsupportedLanguages = new Set()
 
-module.exports = (language, code, lineNumbersHighlight = []) => {
+module.exports = (
+  language,
+  code,
+  lineNumbersHighlight = [],
+  noInlineHighlight = false
+) => {
   // (Try to) load languages on demand.
   if (!Prism.languages[language]) {
     try {
       loadPrismLanguage(language)
     } catch (e) {
       // Language wasn't loaded so let's bail.
-      if (language === `none`) {
-        return code // Don't escape if set to none.
-      } else {
-        const lang = language.toLowerCase()
-        if (!unsupportedLanguages.has(lang)) {
-          console.warn(
-            `unable to find prism language '${lang}' for highlighting.`,
-            `applying generic code block`
-          )
-          unsupportedLanguages.add(lang)
-        }
-        return _.escape(code)
+      let message = null
+      switch (language) {
+        case `none`:
+          return code // Don't escape if set to none.
+        case `text`:
+          message = noInlineHighlight
+            ? `code block language not specified in markdown.`
+            : `code block or inline code language not specified in markdown.`
+          break
+        default:
+          message = `unable to find prism language '${language}' for highlighting.`
       }
+
+      const lang = language.toLowerCase()
+      if (!unsupportedLanguages.has(lang)) {
+        console.warn(message, `applying generic code block`)
+        unsupportedLanguages.add(lang)
+      }
+      return _.escape(code)
     }
   }
 

packages/gatsby-remark-prismjs/src/index.js

@@ -70,7 +70,7 @@ module.exports = (
     + `<div class="${highlightClassName}" data-language="${languageName}">`
     +   `<pre${numLinesStyle} class="${className}${numLinesClass}">`
     +     `<code class="${className}">`
-    +       `${highlightCode(languageName, node.value, highlightLines)}`
+    +       `${highlightCode(languageName, node.value, highlightLines, noInlineHighlight)}`
     +     `</code>`
     +     `${numLinesNumber}`
     +   `</pre>`