From df914d94a7c47c6082b6f165eb44dc6e15e12c7d Mon Sep 17 00:00:00 2001
From: Peter van der Zee <209817+pvdz@users.noreply.github.com>
Date: Tue, 20 Oct 2020 14:22:06 +0200
Subject: [PATCH] perf: implement shouldOnCreateNode for all our
 plugins/benchmarks (#27545)

* perf: implement shouldOnCreateNode for all our plugins

* Drop changes in /benchmarks, fix typo
---
 packages/gatsby-plugin-mdx/gatsby-node.js     | 12 +++++-
 .../gatsby/on-create-node.js                  | 35 +++++++++-------
 .../src/gatsby-node.js                        | 21 +++++-----
 .../gatsby-transformer-csv/src/gatsby-node.js | 20 ++++++----
 .../src/gatsby-node.js                        | 26 +++++++-----
 .../src/gatsby-node.js                        | 40 ++++++++++++++++---
 .../src/gatsby-node.js                        | 25 +++++++-----
 .../src/gatsby-node.js                        | 16 +++++---
 .../src/gatsby-node.js                        | 13 ++++--
 .../src/gatsby-node.js                        | 15 ++++---
 .../gatsby-transformer-pdf/src/gatsby-node.js | 13 ++++--
 .../src/__tests__/on-node-create.js           |  2 +-
 .../src/gatsby-node.js                        |  7 +++-
 .../src/on-node-create.js                     | 10 +++--
 .../src/on-node-create.js                     |  4 +-
 .../src/gatsby-node.js                        | 20 ++++++----
 .../src/on-node-create.js                     |  8 ++--
 .../src/gatsby-node.js                        | 17 +++++---
 .../gatsby-transformer-xml/src/gatsby-node.js | 14 +++++--
 .../src/gatsby-node.js                        | 13 ++++--
 20 files changed, 225 insertions(+), 106 deletions(-)

diff --git a/packages/gatsby-plugin-mdx/gatsby-node.js b/packages/gatsby-plugin-mdx/gatsby-node.js
index 0035204c58d04..e39974ed0a1c9 100644
--- a/packages/gatsby-plugin-mdx/gatsby-node.js
+++ b/packages/gatsby-plugin-mdx/gatsby-node.js
@@ -4,15 +4,25 @@ const { MDX_SCOPES_LOCATION } = require(`./constants`)
 const defaultOptions = require(`./utils/default-options`)
 const fs = require(`fs`)
 
+const {
+  onCreateNode,
+  unstable_shouldOnCreateNode
+} = require(`./gatsby/on-create-node`)
+
 /**
  * Create Mdx types and resolvers
  */
 exports.sourceNodes = require(`./gatsby/source-nodes`)
 
+/**
+ * Check whether to create Mdx nodes from MDX files.
+ */
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 /**
  * Create Mdx nodes from MDX files.
  */
-exports.onCreateNode = require(`./gatsby/on-create-node`)
+exports.onCreateNode = onCreateNode
 
 /**
  * Add frontmatter as page context for MDX pages
diff --git a/packages/gatsby-plugin-mdx/gatsby/on-create-node.js b/packages/gatsby-plugin-mdx/gatsby/on-create-node.js
index b33d246c6f6d9..36258385bd62c 100644
--- a/packages/gatsby-plugin-mdx/gatsby/on-create-node.js
+++ b/packages/gatsby-plugin-mdx/gatsby/on-create-node.js
@@ -10,7 +10,26 @@ const { findImports } = require(`../utils/gen-mdx`)
 
 const contentDigest = val => createContentDigest(val)
 
-module.exports = async (
+function unstable_shouldOnCreateNode({ node }, pluginOptions) {
+  const options = defaultOptions(pluginOptions)
+
+  return _unstable_shouldOnCreateNode({ node }, options)
+}
+
+function _unstable_shouldOnCreateNode({ node }, options) {
+  // options check to stop transformation of the node
+  if (options.shouldBlockNodeFromTransformation(node)) {
+    return false
+  }
+
+  return node.internal.type === `File`
+    ? options.extensions.includes(node.ext)
+    : options.mediaTypes.includes(node.internal.mediaType)
+}
+
+module.exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
+module.exports.onCreateNode = async (
   {
     node,
     loadNodeContent,
@@ -28,19 +47,7 @@ module.exports = async (
   const { createNode, createParentChildLink } = actions
   const options = defaultOptions(pluginOptions)
 
-  // options check to stop transformation of the node
-  if (options.shouldBlockNodeFromTransformation(node)) {
-    return
-  }
-
-  // if we shouldn't process this node, then return
-  if (
-    !(node.internal.type === `File` && options.extensions.includes(node.ext)) &&
-    !(
-      node.internal.type !== `File` &&
-      options.mediaTypes.includes(node.internal.mediaType)
-    )
-  ) {
+  if (!_unstable_shouldOnCreateNode({ node }, options)) {
     return
   }
 
diff --git a/packages/gatsby-transformer-asciidoc/src/gatsby-node.js b/packages/gatsby-transformer-asciidoc/src/gatsby-node.js
index 05a021f4e8a49..c1a0d8f828144 100644
--- a/packages/gatsby-transformer-asciidoc/src/gatsby-node.js
+++ b/packages/gatsby-transformer-asciidoc/src/gatsby-node.js
@@ -1,6 +1,16 @@
 const asciidoc = require(`asciidoctor`)()
 const _ = require(`lodash`)
 
+function unstable_shouldOnCreateNode({ node }, pluginOptions = {}) {
+  const extensionsConfig = pluginOptions.fileExtensions
+
+  // make extensions configurable and use adoc and asciidoc as default
+  const supportedExtensions =
+    extensionsConfig instanceof Array ? extensionsConfig : [`adoc`, `asciidoc`]
+
+  return supportedExtensions.includes(node.extension)
+}
+
 async function onCreateNode(
   {
     node,
@@ -13,15 +23,7 @@ async function onCreateNode(
   },
   pluginOptions
 ) {
-  const extensionsConfig = pluginOptions.fileExtensions
-
-  // make extensions configurable and use adoc and asciidoc as default
-  const supportedExtensions =
-    typeof extensionsConfig !== `undefined` && extensionsConfig instanceof Array
-      ? extensionsConfig
-      : [`adoc`, `asciidoc`]
-
-  if (!supportedExtensions.includes(node.extension)) {
+  if (!unstable_shouldOnCreateNode({ node }, pluginOptions)) {
     return
   }
 
@@ -138,4 +140,5 @@ const extractPageAttributes = allAttributes =>
     return pageAttributes
   }, {})
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-csv/src/gatsby-node.js b/packages/gatsby-transformer-csv/src/gatsby-node.js
index cefed79dc5819..ca06e2dd78211 100644
--- a/packages/gatsby-transformer-csv/src/gatsby-node.js
+++ b/packages/gatsby-transformer-csv/src/gatsby-node.js
@@ -8,20 +8,25 @@ const convertToJson = (data, options) =>
     .fromString(data)
     .then(jsonData => jsonData, new Error(`CSV to JSON conversion failed!`))
 
+function unstable_shouldOnCreateNode({ node }, pluginOptions = {}) {
+  const { extension } = node
+  const { extensions } = pluginOptions
+
+  return extensions ? extensions.includes(extension) : extension === `csv`
+}
+
 async function onCreateNode(
   { node, actions, loadNodeContent, createNodeId, createContentDigest },
   pluginOptions
 ) {
+  if (!unstable_shouldOnCreateNode({ node }, pluginOptions)) {
+    return
+  }
+
   const { createNode, createParentChildLink } = actions
 
   // Destructure out our custom options
-  const { typeName, nodePerFile, extensions, ...options } = pluginOptions || {}
-
-  // Filter out unwanted content
-  const filterExtensions = extensions ?? [`csv`]
-  if (!filterExtensions.includes(node.extension)) {
-    return
-  }
+  const { typeName, nodePerFile, ...options } = pluginOptions || {}
 
   // Load file contents
   const content = await loadNodeContent(node)
@@ -79,4 +84,5 @@ async function onCreateNode(
   return
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-documentationjs/src/gatsby-node.js b/packages/gatsby-transformer-documentationjs/src/gatsby-node.js
index ee4976f443fb9..1bf9f45afad61 100644
--- a/packages/gatsby-transformer-documentationjs/src/gatsby-node.js
+++ b/packages/gatsby-transformer-documentationjs/src/gatsby-node.js
@@ -185,25 +185,29 @@ exports.createResolvers = ({ createResolvers }) => {
   })
 }
 
+function unstable_shouldOnCreateNode({ node }) {
+  return (
+    node.internal.type === `File` &&
+    (node.internal.mediaType === `application/javascript` ||
+      node.extension === `tsx` ||
+      node.extension === `ts`)
+  )
+}
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 /**
  * Implement the onCreateNode API to create documentation.js nodes
  * @param {Object} super this is a super param
  */
 exports.onCreateNode = async ({ node, actions, ...helpers }) => {
-  const { createNodeId, createContentDigest } = helpers
-  const { createNode, createParentChildLink } = actions
-
-  if (
-    node.internal.type !== `File` ||
-    !(
-      node.internal.mediaType === `application/javascript` ||
-      node.extension === `tsx` ||
-      node.extension === `ts`
-    )
-  ) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return null
   }
 
+  const { createNodeId, createContentDigest } = helpers
+  const { createNode, createParentChildLink } = actions
+
   let documentationJson
   try {
     documentationJson = await documentation.build(node.absolutePath, {
diff --git a/packages/gatsby-transformer-excel/src/gatsby-node.js b/packages/gatsby-transformer-excel/src/gatsby-node.js
index d85b7b2b91984..dfe6fbdaacd9f 100644
--- a/packages/gatsby-transformer-excel/src/gatsby-node.js
+++ b/packages/gatsby-transformer-excel/src/gatsby-node.js
@@ -9,17 +9,46 @@ function _loadNodeContent(fileNode, fallback) {
     : fallback(fileNode)
 }
 
+const extensions = [
+  `xls`,
+  `xlsx`,
+  `xlsm`,
+  `xlsb`,
+  `xml`,
+  `xlw`,
+  `xlc`,
+  `csv`,
+  `txt`,
+  `dif`,
+  `sylk`,
+  `slk`,
+  `prn`,
+  `ods`,
+  `fods`,
+  `uos`,
+  `dbf`,
+  `wks`,
+  `123`,
+  `wq1`,
+  `qpw`,
+  `htm`,
+  `html`,
+]
+
+function unstable_shouldOnCreateNode({ node }) {
+  return extensions.includes((node.extension || ``).toLowerCase())
+}
+
 async function onCreateNode(
   { node, actions, loadNodeContent, createNodeId, createContentDigest },
   options = {}
 ) {
-  const { createNode, createParentChildLink } = actions
-  const extensions = `xls|xlsx|xlsm|xlsb|xml|xlw|xlc|csv|txt|dif|sylk|slk|prn|ods|fods|uos|dbf|wks|123|wq1|qpw|htm|html`.split(
-    `|`
-  )
-  if (extensions.indexOf((node.extension || ``).toLowerCase()) == -1) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
+
+  const { createNode, createParentChildLink } = actions
+
   // Load binary string
   const content = await _loadNodeContent(node, loadNodeContent)
 
@@ -86,4 +115,5 @@ async function onCreateNode(
   return
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-hjson/src/gatsby-node.js b/packages/gatsby-transformer-hjson/src/gatsby-node.js
index ab009bc55b551..d47928241a9d9 100644
--- a/packages/gatsby-transformer-hjson/src/gatsby-node.js
+++ b/packages/gatsby-transformer-hjson/src/gatsby-node.js
@@ -2,6 +2,16 @@ const _ = require(`lodash`)
 const path = require(`path`)
 const HJSON = require(`hjson`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // We only care about HJSON content.
+  // NOTE the mime package does not recognize HJSON yet
+  // See RFC https://hjson.org/rfc.html#rfc.section.1.3
+  return (
+    node.internal.mediaType === `text/hjson` ||
+    node.internal.mediaType === `application/hjson`
+  )
+}
+
 async function onCreateNode({
   node,
   actions,
@@ -9,6 +19,10 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
+  if (!unstable_shouldOnCreateNode({ node })) {
+    return
+  }
+
   const { createNode, createParentChildLink } = actions
 
   function transformObject(obj, id, type) {
@@ -27,16 +41,6 @@ async function onCreateNode({
     createParentChildLink({ parent: node, child: jsonNode })
   }
 
-  // We only care about HJSON content.
-  // NOTE the mime package does not recognize HJSON yet
-  // See RFC https://hjson.org/rfc.html#rfc.section.1.3
-  if (
-    node.internal.mediaType !== `text/hjson` &&
-    node.internal.mediaType !== `application/hjson`
-  ) {
-    return
-  }
-
   const content = await loadNodeContent(node)
   const parsedContent = HJSON.parse(content)
 
@@ -59,4 +63,5 @@ async function onCreateNode({
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-javascript-frontmatter/src/gatsby-node.js b/packages/gatsby-transformer-javascript-frontmatter/src/gatsby-node.js
index 420caba781c0b..e15a64a2f1f46 100644
--- a/packages/gatsby-transformer-javascript-frontmatter/src/gatsby-node.js
+++ b/packages/gatsby-transformer-javascript-frontmatter/src/gatsby-node.js
@@ -2,20 +2,25 @@ const _ = require(`lodash`)
 const babylon = require(`@babel/parser`)
 const traverse = require(`@babel/traverse`).default
 
+const fileExtsToProcess = [`js`, `jsx`, `ts`, `tsx`]
+
+function unstable_shouldOnCreateNode({ node }) {
+  // This only processes JavaScript and TypeScript files.
+  return fileExtsToProcess.includes(node.extension)
+}
+
 async function onCreateNode({
   node,
   actions,
   loadNodeContent,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-  const fileExtsToProcess = [`js`, `jsx`, `ts`, `tsx`]
-
-  // This only processes JavaScript and TypeScript files.
-  if (!_.includes(fileExtsToProcess, node.extension)) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   const code = await loadNodeContent(node)
   const options = {
     sourceType: `module`,
@@ -135,4 +140,5 @@ async function onCreateNode({
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-javascript-static-exports/src/gatsby-node.js b/packages/gatsby-transformer-javascript-static-exports/src/gatsby-node.js
index 3ff8d86825258..efdbdddaf2129 100644
--- a/packages/gatsby-transformer-javascript-static-exports/src/gatsby-node.js
+++ b/packages/gatsby-transformer-javascript-static-exports/src/gatsby-node.js
@@ -2,6 +2,11 @@ const _ = require(`lodash`)
 const babylon = require(`@babel/parser`)
 const traverse = require(`@babel/traverse`).default
 
+function unstable_shouldOnCreateNode({ node }) {
+  // This only processes JavaScript files.
+  return node.internal.mediaType === `application/javascript`
+}
+
 async function onCreateNode({
   node,
   getNode,
@@ -10,13 +15,12 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-
-  // This only processes JavaScript files.
-  if (node.internal.mediaType !== `application/javascript`) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   const code = await loadNodeContent(node)
   const options = {
     sourceType: `unambigious`,
@@ -150,4 +154,5 @@ async function onCreateNode({
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-json/src/gatsby-node.js b/packages/gatsby-transformer-json/src/gatsby-node.js
index 65ea7c33193ff..b69fc66a03170 100644
--- a/packages/gatsby-transformer-json/src/gatsby-node.js
+++ b/packages/gatsby-transformer-json/src/gatsby-node.js
@@ -1,10 +1,19 @@
 const _ = require(`lodash`)
 const path = require(`path`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // We only care about JSON content.
+  return node.internal.mediaType === `application/json`
+}
+
 async function onCreateNode(
   { node, actions, loadNodeContent, createNodeId, createContentDigest },
   pluginOptions
 ) {
+  if (!unstable_shouldOnCreateNode({ node })) {
+    return
+  }
+
   function getType({ node, object, isArray }) {
     if (pluginOptions && _.isFunction(pluginOptions.typeName)) {
       return pluginOptions.typeName({ node, object, isArray })
@@ -36,11 +45,6 @@ async function onCreateNode(
 
   const { createNode, createParentChildLink } = actions
 
-  // We only care about JSON content.
-  if (node.internal.mediaType !== `application/json`) {
-    return
-  }
-
   const content = await loadNodeContent(node)
   let parsedContent
   try {
@@ -71,4 +75,5 @@ async function onCreateNode(
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-pdf/src/gatsby-node.js b/packages/gatsby-transformer-pdf/src/gatsby-node.js
index 1c26439b939fe..17857a30a4fb1 100644
--- a/packages/gatsby-transformer-pdf/src/gatsby-node.js
+++ b/packages/gatsby-transformer-pdf/src/gatsby-node.js
@@ -1,6 +1,11 @@
 const Promise = require(`bluebird`)
 const PDFParser = require(`pdf2json`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // Filter out non-pdf content
+  return node.extension === `pdf`
+}
+
 const convertToJson = path =>
   new Promise((res, rej) => {
     const pdfParser = new PDFParser(this, 1)
@@ -21,13 +26,12 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-
-  // Filter out non-pdf content
-  if (node.extension !== `pdf`) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   let parsedContent = await convertToJson(node.absolutePath)
 
   const pdfNode = {
@@ -46,4 +50,5 @@ async function onCreateNode({
   createParentChildLink({ parent: node, child: pdfNode })
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-react-docgen/src/__tests__/on-node-create.js b/packages/gatsby-transformer-react-docgen/src/__tests__/on-node-create.js
index 28025d35a77ea..09b3db08aefe0 100644
--- a/packages/gatsby-transformer-react-docgen/src/__tests__/on-node-create.js
+++ b/packages/gatsby-transformer-react-docgen/src/__tests__/on-node-create.js
@@ -1,6 +1,6 @@
 import fs from "fs"
 import { groupBy } from "lodash"
-import onCreateNode from "../on-node-create"
+import { onCreateNode } from "../on-node-create"
 import path from "path"
 
 const readFile = file =>
diff --git a/packages/gatsby-transformer-react-docgen/src/gatsby-node.js b/packages/gatsby-transformer-react-docgen/src/gatsby-node.js
index 16650dcafbac8..c522a84d3679a 100644
--- a/packages/gatsby-transformer-react-docgen/src/gatsby-node.js
+++ b/packages/gatsby-transformer-react-docgen/src/gatsby-node.js
@@ -1,2 +1,7 @@
-exports.onCreateNode = require(`./on-node-create`).default
+const {
+  onCreateNode,
+  unstable_shouldOnCreateNode,
+} = require(`./on-node-create`)
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+exports.onCreateNode = onCreateNode
 exports.setFieldsOnGraphQLNodeType = require(`./extend-node-type`).default
diff --git a/packages/gatsby-transformer-react-docgen/src/on-node-create.js b/packages/gatsby-transformer-react-docgen/src/on-node-create.js
index 197197860956d..8ecd14e102a32 100644
--- a/packages/gatsby-transformer-react-docgen/src/on-node-create.js
+++ b/packages/gatsby-transformer-react-docgen/src/on-node-create.js
@@ -88,7 +88,11 @@ function createPropNodes(
   return node
 }
 
-export default async function onCreateNode(
+export function unstable_shouldOnCreateNode({ node }) {
+  return canParse(node)
+}
+
+export async function onCreateNode(
   {
     node,
     loadNodeContent,
@@ -99,10 +103,10 @@ export default async function onCreateNode(
   },
   pluginOptions
 ) {
-  const { createNode, createParentChildLink } = actions
-
   if (!canParse(node)) return
 
+  const { createNode, createParentChildLink } = actions
+
   const content = await loadNodeContent(node)
 
   let components
diff --git a/packages/gatsby-transformer-remark/src/on-node-create.js b/packages/gatsby-transformer-remark/src/on-node-create.js
index b47dce011f945..faa91945fb742 100644
--- a/packages/gatsby-transformer-remark/src/on-node-create.js
+++ b/packages/gatsby-transformer-remark/src/on-node-create.js
@@ -19,13 +19,13 @@ module.exports.onCreateNode = async function onCreateNode(
   },
   pluginOptions
 ) {
-  const { createNode, createParentChildLink } = actions
-
   // We only care about markdown content.
   if (!unstable_shouldOnCreateNode({ node })) {
     return {}
   }
 
+  const { createNode, createParentChildLink } = actions
+
   const content = await loadNodeContent(node)
 
   try {
diff --git a/packages/gatsby-transformer-screenshot/src/gatsby-node.js b/packages/gatsby-transformer-screenshot/src/gatsby-node.js
index 280082221e6a1..400ff9c7b66f9 100644
--- a/packages/gatsby-transformer-screenshot/src/gatsby-node.js
+++ b/packages/gatsby-transformer-screenshot/src/gatsby-node.js
@@ -76,21 +76,27 @@ exports.onPreBootstrap = (
   })
 }
 
-exports.onCreateNode = async (
-  { node, actions, store, cache, createNodeId, createContentDigest, getCache },
-  pluginOptions
-) => {
-  const { createNode, createParentChildLink } = actions
-
+function unstable_shouldOnCreateNode({ node }, pluginOptions) {
   /*
    * Check if node is of a type we care about, and has a url field
    * (originally only checked sites.yml, hence including by default)
    */
   const validNodeTypes = [`SitesYaml`].concat(pluginOptions.nodeTypes || [])
-  if (!validNodeTypes.includes(node.internal.type) || !node.url) {
+  return validNodeTypes.includes(node.internal.type) && node.url
+}
+
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
+exports.onCreateNode = async (
+  { node, actions, store, cache, createNodeId, createContentDigest, getCache },
+  pluginOptions
+) => {
+  if (!unstable_shouldOnCreateNode({ node }, pluginOptions)) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   try {
     const screenshotNode = await new Promise((resolve, reject) => {
       screenshotQueue
diff --git a/packages/gatsby-transformer-sharp/src/on-node-create.js b/packages/gatsby-transformer-sharp/src/on-node-create.js
index 30d319187cbf3..035627dcffcf8 100644
--- a/packages/gatsby-transformer-sharp/src/on-node-create.js
+++ b/packages/gatsby-transformer-sharp/src/on-node-create.js
@@ -4,17 +4,19 @@ function unstable_shouldOnCreateNode({ node }) {
   return !!supportedExtensions[node.extension]
 }
 
+module.exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
+
 module.exports.onCreateNode = async function onCreateNode({
   node,
   actions,
   createNodeId,
 }) {
-  const { createNode, createParentChildLink } = actions
-
   if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
 
+  const { createNode, createParentChildLink } = actions
+
   const imageNode = {
     id: createNodeId(`${node.id} >> ImageSharp`),
     children: [],
@@ -30,5 +32,3 @@ module.exports.onCreateNode = async function onCreateNode({
 
   return
 }
-
-module.exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
diff --git a/packages/gatsby-transformer-toml/src/gatsby-node.js b/packages/gatsby-transformer-toml/src/gatsby-node.js
index 944a538ffc2d0..df34d54c430ac 100644
--- a/packages/gatsby-transformer-toml/src/gatsby-node.js
+++ b/packages/gatsby-transformer-toml/src/gatsby-node.js
@@ -1,6 +1,13 @@
 const toml = require(`toml`)
 const _ = require(`lodash`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // Filter out non-toml content
+  // Currently TOML files are considered null in 'mime-db'
+  // Hence the extension test instead of mediaType test
+  return node.extension === `toml`
+}
+
 async function onCreateNode({
   node,
   actions,
@@ -8,13 +15,12 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-  // Filter out non-toml content
-  // Currently TOML files are considered null in 'mime-db'
-  // Hence the extension test instead of mediaType test
-  if (node.extension !== `toml`) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
+
+  const { createNode, createParentChildLink } = actions
+
   // Load TOML contents
   const content = await loadNodeContent(node)
   // Parse
@@ -45,4 +51,5 @@ async function onCreateNode({
   return
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-xml/src/gatsby-node.js b/packages/gatsby-transformer-xml/src/gatsby-node.js
index b603466b3e106..392a48563a20b 100644
--- a/packages/gatsby-transformer-xml/src/gatsby-node.js
+++ b/packages/gatsby-transformer-xml/src/gatsby-node.js
@@ -1,6 +1,11 @@
 const parseXml = require(`xml-parser`)
 const _ = require(`lodash`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  // We only care about XML content.
+  return [`application/xml`, `text/xml`].includes(node.internal.mediaType)
+}
+
 async function onCreateNode({
   node,
   actions,
@@ -8,12 +13,12 @@ async function onCreateNode({
   createNodeId,
   createContentDigest,
 }) {
-  const { createNode, createParentChildLink } = actions
-
-  // We only care about XML content.
-  if (![`application/xml`, `text/xml`].includes(node.internal.mediaType)) {
+  if (!unstable_shouldOnCreateNode({ node })) {
     return
   }
+
+  const { createNode, createParentChildLink } = actions
+
   const rawXml = await loadNodeContent(node)
   const parsedXml = parseXml(rawXml)
   const nodeArray = parsedXml.root.children.map((obj, i) => {
@@ -42,4 +47,5 @@ async function onCreateNode({
   return
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode
diff --git a/packages/gatsby-transformer-yaml/src/gatsby-node.js b/packages/gatsby-transformer-yaml/src/gatsby-node.js
index 9961d7303eaa1..850d65277c5b1 100644
--- a/packages/gatsby-transformer-yaml/src/gatsby-node.js
+++ b/packages/gatsby-transformer-yaml/src/gatsby-node.js
@@ -2,10 +2,18 @@ const jsYaml = require(`js-yaml`)
 const _ = require(`lodash`)
 const path = require(`path`)
 
+function unstable_shouldOnCreateNode({ node }) {
+  return node.internal.mediaType === `text/yaml`
+}
+
 async function onCreateNode(
   { node, actions, loadNodeContent, createNodeId, createContentDigest },
   pluginOptions
 ) {
+  if (!unstable_shouldOnCreateNode({ node })) {
+    return
+  }
+
   function getType({ node, object, isArray }) {
     if (pluginOptions && _.isFunction(pluginOptions.typeName)) {
       return pluginOptions.typeName({ node, object, isArray })
@@ -37,10 +45,6 @@ async function onCreateNode(
 
   const { createNode, createParentChildLink } = actions
 
-  if (node.internal.mediaType !== `text/yaml`) {
-    return
-  }
-
   const content = await loadNodeContent(node)
   const parsedContent = jsYaml.load(content)
 
@@ -61,4 +65,5 @@ async function onCreateNode(
   }
 }
 
+exports.unstable_shouldOnCreateNode = unstable_shouldOnCreateNode
 exports.onCreateNode = onCreateNode