fix(gatsby-source-filesystem): use correct hash when using createFileNodeFromBuffer

packages/gatsby-source-filesystem/README.md

@@ -261,6 +261,8 @@ When working with data that isn't already stored in a file, such as when queryin
 
 The `createFileNodeFromBuffer` helper accepts a `Buffer`, caches its contents to disk, and creates a file node that points to it.
 
+The name of the file can be passed to the `createFileNodeFromBuffer` helper. If no name is given, the content hash will be used to determine the name.
+
 ## Example usage
 
 The following example is adapted from the source of [`gatsby-source-mysql`](https://github.com/malcolm-kee/gatsby-source-mysql):

packages/gatsby-source-filesystem/src/__tests__/create-file-node-from-buffer.js

@@ -18,6 +18,7 @@ jest.mock(`../create-file-node`, () => {
 })
 
 const { ensureDir, writeFile } = require(`fs-extra`)
+const { createContentDigest } = require(`gatsby-core-utils`)
 const { createFileNode } = require(`../create-file-node`)
 const createFileNodeFromBuffer = require(`../create-file-node-from-buffer`)
 
@@ -118,6 +119,44 @@ describe(`create-file-node-from-buffer`, () => {
         expect.any(Object)
       )
     })
+
+    it(`uses hash as filename when no name is provided`, async () => {
+      expect.assertions(1)
+
+      let outputFilename
+      writeFile.mockImplementationOnce((filename, buf, cb) => {
+        outputFilename = filename
+        cb()
+      })
+
+      const buffer = createMockBuffer(`buffer-content`)
+      await setup({
+        hash: `a-given-hash`,
+        buffer: buffer,
+        getCache: () => createMockCache(),
+      })
+
+      expect(outputFilename).toContain(`a-given-hash.bin`)
+    })
+
+    it(`uses generated hash as filename when no name or hash is provided`, async () => {
+      expect.assertions(1)
+
+      let outputFilename
+      writeFile.mockImplementationOnce((filename, buf, cb) => {
+        outputFilename = filename
+        cb()
+      })
+
+      const buffer = createMockBuffer(`buffer-content`)
+      const expectedHash = createContentDigest(buffer)
+      await setup({
+        buffer: buffer,
+        getCache: () => createMockCache(),
+      })
+
+      expect(outputFilename).toContain(`${expectedHash}.bin`)
+    })
   })
 
   describe(`validation`, () => {

packages/gatsby-source-filesystem/src/create-file-node-from-buffer.js

@@ -72,7 +72,6 @@ async function processBufferNode({
       const filetype = await fileType.fromBuffer(buffer)
       ext = filetype ? `.${filetype.ext}` : `.bin`
     }
-
     filename = createFilePath(path.join(pluginCacheDir, hash), name, ext)
     await fs.ensureDir(path.dirname(filename))
 
@@ -125,7 +124,7 @@ module.exports = ({
   parentNodeId = null,
   createNodeId,
   ext,
-  name = hash,
+  name,
 }) => {
   // validation of the input
   // without this it's notoriously easy to pass in the wrong `createNodeId`
@@ -156,6 +155,10 @@ module.exports = ({
     hash = createContentDigest(buffer)
   }
 
+  if (!name) {
+    name = hash
+  }
+
   // Check if we already requested node for this remote file
   // and return stored promise if we did.
   if (processingCache[hash]) {