feat(config): support TOML configuration files (#4877)

* Add initial support for TOML in configuration files

* Missed brace

* Fix snapshots

* refactor: move loadToml to utils

* Use @iarna/toml

* Add tests for loadToml

* Fix test for CI

* Remove jest-extended

* Create snapshot for load-toml

* Add feat to docs

* lint docs

* Use @iarna/toml/parse-string

* Change path string

docs/configuration.md

@@ -6,6 +6,7 @@ title: Configuration File
 Prettier uses [cosmiconfig](https://github.com/davidtheclark/cosmiconfig) for configuration file support. This means you can configure prettier via:
 
 - A `.prettierrc` file, written in YAML or JSON, with optional extensions: `.yaml/.yml/.json/.js`.
+- A `.prettierrc.toml` file, written in TOML (the `.toml` extension is _required_).
 - A `prettier.config.js` file that exports an object.
 - A `"prettier"` key in your `package.json` file.
 
@@ -42,6 +43,14 @@ printWidth: 100
 parser: flow
 ```
 
+TOML:
+
+```toml
+# .prettierrc.toml
+printWidth = 100
+parser = "flow"
+```
+
 ## Configuration Overrides
 
 Prettier borrows eslint's [override format](http://eslint.org/docs/user-guide/configuring#example-configuration). This allows you to apply configuration to specific files.

package.json

@@ -17,6 +17,7 @@
     "@babel/code-frame": "7.0.0-beta.46",
     "@babel/parser": "7.0.0-beta.55",
     "@glimmer/syntax": "0.30.3",
+    "@iarna/toml": "2.0.0",
     "camelcase": "4.1.0",
     "chalk": "2.1.0",
     "cjk-regex": "1.0.2",

src/config/resolve-config.js

@@ -6,6 +6,7 @@ const path = require("path");
 const mem = require("mem");
 
 const resolveEditorConfig = require("./resolve-config-editorconfig");
+const loadToml = require("../utils/load-toml");
 
 const getExplorerMemoized = mem(opts => {
   const explorer = thirdParty.cosmiconfig("prettier", {
@@ -22,6 +23,19 @@ const getExplorerMemoized = mem(opts => {
         delete result.config.$schema;
       }
       return result;
+    },
+    searchPlaces: [
+      "package.json",
+      ".prettierrc",
+      ".prettierrc.json",
+      ".prettierrc.yaml",
+      ".prettierrc.yml",
+      ".prettierrc.js",
+      "prettier.config.js",
+      ".prettierrc.toml"
+    ],
+    loaders: {
+      ".toml": loadToml
     }
   });
 

src/utils/load-toml.js

@@ -0,0 +1,12 @@
+"use strict";
+
+const parse = require("@iarna/toml/parse-string");
+
+module.exports = function(filePath, content) {
+  try {
+    return parse(content);
+  } catch (error) {
+    error.message = `TOML Error in ${filePath}:\n${error.message}`;
+    throw error;
+  }
+};

tests_integration/__tests__/__snapshots__/config-resolution.js.snap

@@ -62,6 +62,16 @@ function rcJson() {
     ],
   );
 }
+function rcToml() {
+  console.log.apply(
+    null,
+    [
+      'rc-toml/file.js',
+      'should have trailing comma',
+      'and single quotes',
+    ],
+  );
+}
 function rcYaml() {
   console.log.apply(
     null,
@@ -142,6 +152,13 @@ function rcJson() {
     'and single quotes',
   ]);
 }
+function rcToml() {
+  console.log.apply(null, [
+    'rc-toml/file.js',
+    'should have trailing comma',
+    'and single quotes',
+  ]);
+}
 function rcYaml() {
   console.log.apply(null, [
     'rc-yaml/file.js',
@@ -181,6 +198,15 @@ exports[`resolves json configuration file with --find-config-path file (stdout)
 
 exports[`resolves json configuration file with --find-config-path file (write) 1`] = `Array []`;
 
+exports[`resolves toml configuration file with --find-config-path file (stderr) 1`] = `""`;
+
+exports[`resolves toml configuration file with --find-config-path file (stdout) 1`] = `
+"rc-toml/.prettierrc.toml
+"
+`;
+
+exports[`resolves toml configuration file with --find-config-path file (write) 1`] = `Array []`;
+
 exports[`resolves yaml configuration file with --find-config-path file (stderr) 1`] = `""`;
 
 exports[`resolves yaml configuration file with --find-config-path file (stdout) 1`] = `

tests_integration/__tests__/__snapshots__/load-toml.js.snap

@@ -0,0 +1,36 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`TOML loads toml successfully 1`] = `
+Object {
+  "database": Object {
+    "connection_max": 5000,
+    "enabled": true,
+    "ports": Array [
+      8001,
+      8001,
+      8002,
+    ],
+    "server": "192.168.1.1",
+    Symbol(type): Symbol(table),
+    Symbol(declared): true,
+  },
+  "owner": Object {
+    "dob": 1979-05-27T15:32:00.000Z,
+    "name": "Tom Preston-Werner",
+    Symbol(type): Symbol(table),
+    Symbol(declared): true,
+  },
+  "title": "TOML Example",
+  Symbol(type): Symbol(table),
+  Symbol(declared): false,
+}
+`;
+
+exports[`TOML throws error on incorrect toml 1`] = `
+"TOML Error in example.toml:
+Unknown character \\"47\\" at row 1, col 2, pos 1:
+1> ///ERROR///
+    ^
+
+"
+`;

tests_integration/__tests__/__snapshots__/with-config-precedence.js.snap

@@ -139,6 +139,16 @@ function rcJson() {
     ],
   );
 }
+function rcToml() {
+  console.log.apply(
+    null,
+    [
+      'rc-toml/file.js',
+      'should have trailing comma',
+      'and single quotes',
+    ],
+  );
+}
 function rcYaml() {
   console.log.apply(
     null,
@@ -216,6 +226,16 @@ function rcJson() {
     ],
   );
 }
+function rcToml() {
+  console.log.apply(
+    null,
+    [
+      'rc-toml/file.js',
+      'should have trailing comma',
+      'and single quotes',
+    ],
+  );
+}
 function rcYaml() {
   console.log.apply(
     null,

tests_integration/__tests__/config-resolution.js

@@ -43,6 +43,12 @@ describe("resolves yaml configuration file with --find-config-path file", () =>
   });
 });
 
+describe("resolves toml configuration file with --find-config-path file", () => {
+  runPrettier("cli/config/", ["--find-config-path", "rc-toml/file.js"]).test({
+    status: 0
+  });
+});
+
 describe("prints nothing when no file found with --find-config-path", () => {
   runPrettier("cli/config/", ["--find-config-path", ".."]).test({
     stdout: "",

tests_integration/__tests__/load-toml.js

@@ -0,0 +1,37 @@
+"use strict";
+
+const loadToml = require("../../src/utils/load-toml");
+
+describe("TOML", () => {
+  const exampleFilePath = "example.toml";
+
+  const exampleToml = `
+# This is a TOML document.
+title = "TOML Example"
+[owner]
+name = "Tom Preston-Werner"
+dob = 1979-05-27T07:32:00-08:00 # First class dates
+[database]
+server = "192.168.1.1"
+ports = [ 8001, 8001, 8002 ]
+connection_max = 5000
+enabled = true
+`;
+
+  const wrongToml = "///ERROR///";
+
+  test("loads toml successfully", () => {
+    const parsedToml = loadToml(exampleFilePath, exampleToml);
+    expect(parsedToml).toMatchSnapshot();
+  });
+
+  test("throws error on incorrect toml", () => {
+    expect(() => {
+      loadToml(exampleFilePath, wrongToml);
+    }).toThrow();
+
+    expect(() => {
+      loadToml(exampleFilePath, wrongToml);
+    }).toThrowErrorMatchingSnapshot();
+  });
+});

tests_integration/cli/config/rc-toml/.prettierrc.toml

@@ -0,0 +1,2 @@
+trailingComma = "all"
+singleQuote = true

tests_integration/cli/config/rc-toml/file.js

@@ -0,0 +1,7 @@
+function rcToml() {
+  console.log.apply(null, [
+    "rc-toml/file.js",
+    "should have trailing comma",
+    "and single quotes"
+  ]);
+}

yarn.lock

@@ -563,6 +563,10 @@
   dependencies:
     "@glimmer/util" "^0.30.3"
 
+"@iarna/toml@2.0.0":
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/@iarna/toml/-/toml-2.0.0.tgz#7802115684397785b3b6dc8a3ba50e30d7a7422b"
+
 "@types/commander@^2.11.0":
   version "2.12.2"
   resolved "https://registry.yarnpkg.com/@types/commander/-/commander-2.12.2.tgz#183041a23842d4281478fa5d23c5ca78e6fd08ae"