feat(gatsby-core-utils,gatsby-cli): Allow write to gatsby-config.ts

packages/gatsby-cli/package.json

@@ -14,6 +14,7 @@
     "@babel/core": "^7.15.5",
     "@babel/generator": "^7.16.8",
     "@babel/helper-plugin-utils": "^7.16.7",
+    "@babel/preset-typescript": "^7.16.7",
     "@babel/runtime": "^7.15.4",
     "@babel/template": "^7.16.7",
     "@babel/types": "^7.16.8",

packages/gatsby-cli/src/__tests__/handlers/__snapshots__/plugin-add.ts.snap

@@ -0,0 +1,104 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`addPlugins gatsby-config.js should not write with no plugins 1`] = `
+"module.exports = {
+  siteMetadata: {
+    siteUrl: \`https://www.yourdomain.tld\`,
+  },
+  plugins: [],
+}
+"
+`;
+
+exports[`addPlugins gatsby-config.js should write a plugin with options 1`] = `
+"module.exports = {
+  siteMetadata: {
+    siteUrl: \`https://www.yourdomain.tld\`
+  },
+  plugins: [{
+    resolve: 'gatsby-plugin-hello',
+    options: {
+      \\"greet\\": true
+    }
+  }]
+};"
+`;
+
+exports[`addPlugins gatsby-config.js should write a single plugin 1`] = `
+"module.exports = {
+  siteMetadata: {
+    siteUrl: \`https://www.yourdomain.tld\`
+  },
+  plugins: [\\"gatsby-plugin-hello\\"]
+};"
+`;
+
+exports[`addPlugins gatsby-config.js should write multiple plugins 1`] = `
+"module.exports = {
+  siteMetadata: {
+    siteUrl: \`https://www.yourdomain.tld\`
+  },
+  plugins: [\\"gatsby-plugin-hello\\", \\"gatsby-plugin-world\\"]
+};"
+`;
+
+exports[`addPlugins gatsby-config.ts should not write with no plugins 1`] = `
+"import type { GatsbyConfig } from \\"gatsby\\"
+
+const config: GatsbyConfig = {
+  siteMetadata: {
+    siteUrl: \`https://www.yourdomain.tld\`,
+  },
+  plugins: [],
+}
+
+export default config
+"
+`;
+
+exports[`addPlugins gatsby-config.ts should write a plugin with options 1`] = `
+"import type { GatsbyConfig } from 'gatsby;'
+
+const config: GatsbyConfig = {
+  siteMetadata: {
+    siteUrl: \`https://www.yourdomain.tld\`
+  },
+  plugins: [{
+    resolve: 'gatsby-plugin-hello',
+    options: {
+      \\"greet\\": true
+    }
+  }]
+};
+
+export default config;
+"
+`;
+
+exports[`addPlugins gatsby-config.ts should write a single plugin 1`] = `
+"import type { GatsbyConfig } from 'gatsby;'
+
+const config: GatsbyConfig = {
+  siteMetadata: {
+    siteUrl: \`https://www.yourdomain.tld\`
+  },
+  plugins: [\\"gatsby-plugin-hello\\"]
+};
+
+export default config;
+"
+`;
+
+exports[`addPlugins gatsby-config.ts should write multiple plugins 1`] = `
+"import type { GatsbyConfig } from 'gatsby;'
+
+const config: GatsbyConfig = {
+  siteMetadata: {
+    siteUrl: \`https://www.yourdomain.tld\`
+  },
+  plugins: [\\"gatsby-plugin-hello\\", \\"gatsby-plugin-world\\"]
+};
+
+export default config;
+"
+`;

packages/gatsby-cli/src/__tests__/handlers/plugin-add.ts

@@ -0,0 +1,121 @@
+import { copyFile, readFile, rm } from "fs/promises"
+import { ensureDir } from "fs-extra"
+import { join } from "path"
+import { addPlugins } from "../../handlers/plugin-add"
+
+/**
+ * Copy files from minimal starters instead of testing against static gatsby-configs
+ * in fixtues so that these break if we change the starter configs in a breaking way.
+ *
+ * Not using `jest.each` since I find that much harder to read and debug.
+ * @see {@link https://jestjs.io/docs/api#testeachtablename-fn-timeout}
+ */
+
+const root = join(__dirname, `../../../../..`)
+const fixtures = join(__dirname, `../fixtures`)
+const config = {
+  js: {
+    starter: `${root}/starters/gatsby-starter-minimal/gatsby-config.js`,
+    fixture: `${fixtures}/gatsby-config.js`,
+  },
+  ts: {
+    starter: `${root}/starters/gatsby-starter-minimal-ts/gatsby-config.ts`,
+    fixture: `${fixtures}/gatsby-config.ts`,
+  },
+}
+const plugin = {
+  hello: `gatsby-plugin-hello`,
+  world: `gatsby-plugin-world`,
+}
+
+describe(`addPlugins`, () => {
+  beforeAll(async () => {
+    await ensureDir(fixtures)
+  })
+
+  describe(`gatsby-config.js`, () => {
+    beforeEach(async () => {
+      await copyFile(config.js.starter, config.js.fixture)
+    })
+
+    afterEach(async () => {
+      await rm(config.js.fixture)
+    })
+
+    it(`should not write with no plugins`, async () => {
+      await addPlugins([], {}, fixtures, [])
+      const gatsbyConfig = (await readFile(config.js.fixture)).toString()
+      expect(gatsbyConfig).toMatchSnapshot()
+    })
+
+    it(`should write a single plugin`, async () => {
+      await addPlugins([plugin.hello], {}, fixtures, [])
+      const gatsbyConfig = (await readFile(config.js.fixture)).toString()
+      expect(gatsbyConfig).toMatchSnapshot()
+    })
+
+    it(`should write multiple plugins`, async () => {
+      await addPlugins([plugin.hello, plugin.world], {}, fixtures, [])
+      const gatsbyConfig = (await readFile(config.js.fixture)).toString()
+      expect(gatsbyConfig).toMatchSnapshot()
+    })
+
+    it(`should write a plugin with options`, async () => {
+      await addPlugins(
+        [plugin.hello],
+        {
+          [plugin.hello]: {
+            greet: true,
+          },
+        },
+        fixtures,
+        []
+      )
+      const gatsbyConfig = (await readFile(config.js.fixture)).toString()
+      expect(gatsbyConfig).toMatchSnapshot()
+    })
+  })
+
+  describe(`gatsby-config.ts`, () => {
+    beforeEach(async () => {
+      await copyFile(config.ts.starter, config.ts.fixture)
+    })
+
+    afterEach(async () => {
+      await rm(config.ts.fixture)
+    })
+
+    it(`should not write with no plugins`, async () => {
+      await addPlugins([], {}, fixtures, [])
+      const gatsbyConfig = (await readFile(config.ts.fixture)).toString()
+      expect(gatsbyConfig).toMatchSnapshot()
+    })
+
+    it(`should write a single plugin`, async () => {
+      await addPlugins([plugin.hello], {}, fixtures, [])
+      const gatsbyConfig = (await readFile(config.ts.fixture)).toString()
+      expect(gatsbyConfig).toMatchSnapshot()
+    })
+
+    it(`should write multiple plugins`, async () => {
+      await addPlugins([plugin.hello, plugin.world], {}, fixtures, [])
+      const gatsbyConfig = (await readFile(config.ts.fixture)).toString()
+      expect(gatsbyConfig).toMatchSnapshot()
+    })
+
+    it(`should write a plugin with options`, async () => {
+      await addPlugins(
+        [plugin.hello],
+        {
+          [plugin.hello]: {
+            greet: true,
+          },
+        },
+        fixtures,
+        []
+      )
+      const gatsbyConfig = (await readFile(config.ts.fixture)).toString()
+      expect(gatsbyConfig).toMatchSnapshot()
+    })
+  })
+})

packages/gatsby-cli/src/handlers/plugin-add-utils.ts

@@ -7,11 +7,12 @@ import {
   getConfigPath,
   getConfigStore,
 } from "gatsby-core-utils"
-import { transform } from "@babel/core"
-import { BabelPluginAddPluginsToGatsbyConfig } from "./plugin-babel-utils"
+import { transform, TransformOptions } from "@babel/core"
+import BabelPluginAddPluginsToGatsbyConfig from "./plugin-babel-utils"
 
 const addPluginToConfig = (
   src: string,
+  srcPath: string,
   {
     name,
     options,
@@ -22,19 +23,41 @@ const addPluginToConfig = (
     key: string
   }
 ): string => {
-  const addPlugins = new BabelPluginAddPluginsToGatsbyConfig({
-    pluginOrThemeName: name,
-    options,
-    shouldAdd: true,
-    key,
-  })
+  let code
 
-  // @ts-ignore - fix me
-  const { code } = transform(src, {
-    // @ts-ignore - fix me
-    plugins: [addPlugins.plugin],
-    configFile: false,
-  })
+  try {
+    const transformOptions: TransformOptions = {
+      plugins: [
+        [
+          BabelPluginAddPluginsToGatsbyConfig,
+          {
+            pluginOrThemeName: name,
+            options,
+            key,
+          },
+        ],
+      ],
+      filename: srcPath,
+      configFile: false,
+    }
+
+    // Use the Babel TS preset if we're operating on `gatsby-config.ts`
+    if (srcPath.endsWith(`ts`)) {
+      transformOptions.presets = [`@babel/preset-typescript`]
+    }
+
+    code = transform(src, transformOptions)?.code
+
+    // Add back stripped type import, do light formatting, remove added empty module export.
+    // Use semicolon since Babel does that anyway, and we might as well be consistent.
+    if (srcPath.endsWith(`ts`)) {
+      code = `import type { GatsbyConfig } from 'gatsby;'\n\n${code}`
+      code = code.replace(`export {};`, ``)
+      code = code.replace(`export default config;`, `\nexport default config;`)
+    }
+  } catch (error) {
+    console.error(`Failed to transform gatsby config`, error)
+  }
 
   return code
 }
@@ -53,10 +76,13 @@ export const GatsbyPluginCreate = async ({
   key,
 }: IGatsbyPluginCreateInput): Promise<void> => {
   const release = await lock(`gatsby-config.js`)
+  const configSrcPath = getConfigPath(root)
   const configSrc = await readConfigFile(root)
-
-  const code = addPluginToConfig(configSrc, { name, options, key })
-
+  const code = addPluginToConfig(configSrc, configSrcPath, {
+    name,
+    options,
+    key,
+  })
   await fs.writeFile(getConfigPath(root), code)
   release()
 }

packages/gatsby-cli/src/handlers/plugin-add.ts

@@ -54,7 +54,7 @@ async function installPluginConfig(
       options,
       key: pluginKey,
     })
-    reporter.info(`Installed ${pluginName || pluginKey} in gatsby-config.js`)
+    reporter.info(`Installed ${pluginName || pluginKey} in gatsby-config`)
   } catch (err) {
     reporter.error(JSON.parse(err)?.message)
     installTimer.setStatus(`FAILED`)