fix: add fs.promises to linked filesystem (#441)

* fix: add fs.promises to linked filesystem

* test: add coverage for linking of fs.promises

* fix: accidentally removed a logging statement

Author: ericapisani

plugin/src/templates/utils.ts

@@ -94,6 +94,12 @@ export async function prepareFilesystem(
       lfs[key].native = fs[key].native
     }
   }
+
+  // 'promises' is not initially linked within the 'linkfs'
+  // package, and is needed by underlying Gatsby code (the
+  // @graphql-tools/code-file-loader)
+  lfs.promises = link(fs.promises, rewrites)
+
   // Gatsby uses this instead of fs if present
   // eslint-disable-next-line no-underscore-dangle
   global._fsWrapper = lfs

plugin/test/unit/templates/utils.spec.ts

@@ -62,6 +62,20 @@ describe('prepareFilesystem', () => {
     delete process.env.GATSBY_EXCLUDE_DATASTORE_FROM_BUNDLE
   }, TEST_TIMEOUT)
 
+  it(
+    'links fs.promises to ensure it is available on global._fsWrapper',
+    async () => {
+      await moveGatsbyDir()
+
+      const cacheDir = resolve('.cache')
+      await templateUtils.prepareFilesystem(cacheDir, chance.url())
+
+      // eslint-disable-next-line no-underscore-dangle
+      expect(global._fsWrapper.promises).toBeDefined()
+    },
+    TEST_TIMEOUT,
+  )
+
   it(
     'downloads file from the CDN when GATSBY_EXCLUDE_DATASTORE_FROM_BUNDLE is enabled',
     async () => {