Implement getSupportInfo() and use it for inference (#3033)

* Implement getSupportInfo() and use it for inference

* Add comment with source of languages.yml

* Fix build, pin semver

* Simplify test snapshots

* Remove stray 'type' property

* Fix parser being overwritten

* Don't infer unreleased parser from extension

* Add CLI and docs for support info

.prettierignore

@@ -0,0 +1 @@
+dist/

README.md

@@ -340,6 +340,12 @@ Prettier CLI will ignore files located in `node_modules` directory. To opt-out f
 
 This rewrites all processed files in place.  This is comparable to the `eslint --fix` workflow.
 
+<!--
+#### `--support-info`
+
+Prints, as JSON, the [support information](#prettiergetsupportinfoversion) for the current version of Prettier.
+-->
+
 ### ESLint
 
 If you are using ESLint, integrating Prettier to your workflow is straightforward:
@@ -503,6 +509,38 @@ As you repeatedly call `resolveConfig`, the file system structure will be cached
 This function will clear the cache. Generally this is only needed for editor integrations that
 know that the file system has changed since the last format took place.
 
+<!--
+#### `prettier.getSupportInfo([version])`
+
+Returns an object representing the parsers, languages and file types Prettier
+supports.
+
+If `version` is provided (e.g. `"1.5.0"`), information for that version will be
+returned, otherwise information for the current version will be returned.
+
+The support information looks like this:
+
+```
+{
+  languages: Array<{
+    name: string,
+    since: string,
+    parsers: string[],
+    group?: string,
+    tmScope: string,
+    aceMode: string,
+    codemirrorMode: string,
+    codemirrorMimeType: string,
+    aliases?: string[],
+    extensions: string[],
+    filenames?: string[],
+    linguistLanguageId: number,
+    vscodeLanguageIds: string[],
+  }>
+}
+```
+-->
+
 #### Custom Parser API
 
 If you need to make modifications to the AST (such as codemods), or you want to provide an alternate parser, you can do so by setting the `parser` option to a function. The function signature of the parser function is:

index.js

@@ -10,6 +10,7 @@ const normalizeOptions = require("./src/options").normalize;
 const parser = require("./src/parser");
 const printDocToDebug = require("./src/doc-debug").printDocToDebug;
 const config = require("./src/resolve-config");
+const getSupportInfo = require("./src/support").getSupportInfo;
 const docblock = require("jest-docblock");
 const getStream = require("get-stream");
 
@@ -382,6 +383,8 @@ module.exports = {
   resolveConfig: config.resolveConfig,
   clearConfigCache: config.clearCache,
 
+  getSupportInfo,
+
   version,
 
   /* istanbul ignore next */

package.json

@@ -44,6 +44,7 @@
     "postcss-values-parser": "1.3.1",
     "remark-frontmatter": "1.1.0",
     "remark-parse": "4.0.0",
+    "semver": "5.4.1",
     "string-width": "2.1.1",
     "strip-bom": "3.0.0",
     "typescript": "2.5.3",

src/cli-constant.js

@@ -271,6 +271,10 @@ const detailedOptions = normalizeDetailedOptions({
     forwardToApi: "filepath",
     description: "Path to the file to pretend that stdin comes from."
   },
+  "support-info": {
+    type: "boolean",
+    description: "Print support information as JSON."
+  },
   "tab-width": {
     type: "int",
     category: CATEGORY_FORMAT,

src/cli.js

@@ -37,6 +37,15 @@ function run(args) {
     process.exit(0);
   }
 
+  if (argv["support-info"]) {
+    console.log(
+      prettier.format(JSON.stringify(prettier.getSupportInfo()), {
+        parser: "json"
+      })
+    );
+    process.exit(0);
+  }
+
   const hasFilePatterns = argv.__filePatterns.length !== 0;
   const useStdin = argv["stdin"] || (!hasFilePatterns && !process.stdin.isTTY);
 

src/options.js

@@ -1,7 +1,10 @@
 "use strict";
 
+const path = require("path");
+
 const validate = require("jest-validate").validate;
 const deprecatedConfig = require("./deprecated");
+const supportTable = require("./support").supportTable;
 
 const defaults = {
   cursorOffset: -1,
@@ -31,22 +34,24 @@ function normalize(options) {
   const normalized = Object.assign({}, options || {});
   const filepath = normalized.filepath;
 
-  if (/\.css$/.test(filepath)) {
+  if (
-    normalized.parser = "css";
+    filepath &&
-  } else if (/\.less$/.test(filepath)) {
+    (!normalized.parser || normalized.parser === defaults.parser)
-    normalized.parser = "less";
+  ) {
-  } else if (/\.scss$/.test(filepath)) {
+    const extension = path.extname(filepath);
-    normalized.parser = "scss";
+    const filename = path.basename(filepath).toLowerCase();
-  } else if (/\.html$/.test(filepath)) {
+
-    normalized.parser = "parse5";
+    const language = supportTable.find(
-  } else if (/\.(ts|tsx)$/.test(filepath)) {
+      language =>
-    normalized.parser = "typescript";
+        typeof language.since === "string" &&
-  } else if (/\.(graphql|gql)$/.test(filepath)) {
+        (language.extensions.indexOf(extension) > -1 ||
-    normalized.parser = "graphql";
+          (language.filenames &&
-  } else if (/\.json$/.test(filepath)) {
+            language.filenames.find(name => name.toLowerCase() === filename)))
-    normalized.parser = "json";
+    );
-  } else if (/\.(md|markdown)$/.test(filepath)) {
+
-    normalized.parser = "markdown";
+    if (language) {
+      normalized.parser = language.parsers[0];
+    }
   }
 
   if (normalized.parser === "json") {

src/support.js

@@ -0,0 +1,216 @@
+"use strict";
+
+const semver = require("semver");
+const currentVersion = require("../package.json").version;
+
+// Based on:
+// https://github.com/github/linguist/blob/master/lib/linguist/languages.yml
+
+const supportTable = [
+  {
+    name: "JavaScript",
+    since: "0.0.0",
+    parsers: ["babylon", "flow"],
+    group: "JavaScript",
+    tmScope: "source.js",
+    aceMode: "javascript",
+    codemirrorMode: "javascript",
+    codemirrorMimeType: "text/javascript",
+    aliases: ["js", "node"],
+    extensions: [
+      ".js",
+      "._js",
+      ".bones",
+      ".es",
+      ".es6",
+      ".frag",
+      ".gs",
+      ".jake",
+      ".jsb",
+      ".jscad",
+      ".jsfl",
+      ".jsm",
+      ".jss",
+      ".mjs",
+      ".njs",
+      ".pac",
+      ".sjs",
+      ".ssjs",
+      ".xsjs",
+      ".xsjslib"
+    ],
+    filenames: ["Jakefile"],
+    linguistLanguageId: 183,
+    vscodeLanguageIds: ["javascript"]
+  },
+  {
+    name: "JSX",
+    since: "0.0.0",
+    parsers: ["babylon", "flow"],
+    group: "JavaScript",
+    extensions: [".jsx"],
+    tmScope: "source.js.jsx",
+    aceMode: "javascript",
+    codemirrorMode: "jsx",
+    codemirrorMimeType: "text/jsx",
+    liguistLanguageId: 178,
+    vscodeLanguageIds: ["javascriptreact"]
+  },
+  {
+    name: "TypeScript",
+    since: "1.4.0",
+    parsers: ["typescript"],
+    group: "JavaScript",
+    aliases: ["ts"],
+    extensions: [".ts", ".tsx"],
+    tmScope: "source.ts",
+    aceMode: "typescript",
+    codemirrorMode: "javascript",
+    codemirrorMimeType: "application/typescript",
+    liguistLanguageId: 378,
+    vscodeLanguageIds: ["typescript", "typescriptreact"]
+  },
+  {
+    name: "CSS",
+    since: "1.4.0",
+    parsers: ["css"],
+    group: "CSS",
+    tmScope: "source.css",
+    aceMode: "css",
+    codemirrorMode: "css",
+    codemirrorMimeType: "text/css",
+    extensions: [".css"],
+    liguistLanguageId: 50,
+    vscodeLanguageIds: ["css"]
+  },
+  {
+    name: "Less",
+    since: "1.4.0",
+    parsers: ["less"],
+    group: "CSS",
+    extensions: [".less"],
+    tmScope: "source.css.less",
+    aceMode: "less",
+    codemirrorMode: "css",
+    codemirrorMimeType: "text/css",
+    liguistLanguageId: 198,
+    vscodeLanguageIds: ["less"]
+  },
+  {
+    name: "SCSS",
+    since: "1.4.0",
+    parsers: ["scss"],
+    group: "CSS",
+    tmScope: "source.scss",
+    aceMode: "scss",
+    codemirrorMode: "css",
+    codemirrorMimeType: "text/x-scss",
+    extensions: [".scss"],
+    liguistLanguageId: 329,
+    vscodeLanguageIds: ["scss"]
+  },
+  {
+    name: "GraphQL",
+    since: "1.5.0",
+    parsers: ["graphql"],
+    extensions: [".graphql", ".gql"],
+    tmScope: "source.graphql",
+    aceMode: "text",
+    liguistLanguageId: 139,
+    vscodeLanguageIds: ["graphql"]
+  },
+  {
+    name: "JSON",
+    since: "1.5.0",
+    parsers: ["json"],
+    group: "JavaScript",
+    tmScope: "source.json",
+    aceMode: "json",
+    codemirrorMode: "javascript",
+    codemirrorMimeType: "application/json",
+    extensions: [
+      ".json",
+      ".json5",
+      ".geojson",
+      ".JSON-tmLanguage",
+      ".topojson"
+    ],
+    filenames: [
+      ".arcconfig",
+      ".jshintrc",
+      ".babelrc",
+      ".eslintrc",
+      ".prettierrc",
+      "composer.lock",
+      "mcmod.info"
+    ],
+    linguistLanguageId: 174,
+    vscodeLanguageIds: ["json"]
+  },
+
+  {
+    name: "Markdown",
+    since: "1.8.0",
+    parsers: ["markdown"],
+    aliases: ["pandoc"],
+    aceMode: "markdown",
+    codemirrorMode: "gfm",
+    codemirrorMimeType: "text/x-gfm",
+    wrap: true,
+    extensions: [
+      ".md",
+      ".markdown",
+      ".mdown",
+      ".mdwn",
+      ".mkd",
+      ".mkdn",
+      ".mkdown",
+      ".ron",
+      ".workbook"
+    ],
+    filenames: ["README"],
+    tmScope: "source.gfm",
+    linguistLanguageId: 222,
+    vscodeLanguageIds: ["markdown"]
+  },
+  {
+    name: "HTML",
+    since: undefined, // unreleased
+    parsers: ["parse5"],
+    group: "HTML",
+    tmScope: "text.html.basic",
+    aceMode: "html",
+    codemirrorMode: "htmlmixed",
+    codemirrorMimeType: "text/html",
+    aliases: ["xhtml"],
+    extensions: [".html", ".htm", ".html.hl", ".inc", ".st", ".xht", ".xhtml"],
+    linguistLanguageId: 146,
+    vscodeLanguageIds: ["html"]
+  }
+];
+
+function getSupportInfo(version) {
+  if (!version) {
+    version = currentVersion;
+  }
+
+  const usePostCssParser = semver.lt(version, "1.7.1");
+
+  const languages = supportTable
+    .filter(language => language.since && semver.gte(version, language.since))
+    .map(language => {
+      if (usePostCssParser && language.group === "CSS") {
+        return Object.assign({}, language, {
+          parsers: ["postcss"]
+        });
+      }
+      return language;
+    });
+
+  return { languages };
+}
+
+module.exports = {
+  supportTable,
+  getSupportInfo
+};

tests_integration/__tests__/__snapshots__/early-exit.js.snap

@@ -349,6 +349,17 @@ exports[`show detailed usage with --help stdin-filepath (stdout) 1`] = `
 
 exports[`show detailed usage with --help stdin-filepath (write) 1`] = `Array []`;
 
+exports[`show detailed usage with --help support-info (stderr) 1`] = `""`;
+
+exports[`show detailed usage with --help support-info (stdout) 1`] = `
+"--support-info
+
+  Print support information as JSON.
+"
+`;
+
+exports[`show detailed usage with --help support-info (write) 1`] = `Array []`;
+
 exports[`show detailed usage with --help tab-width (stderr) 1`] = `""`;
 
 exports[`show detailed usage with --help tab-width (stdout) 1`] = `
@@ -503,6 +514,7 @@ Other options:
                            Defaults to false.
   --stdin                  Force reading input from stdin.
   --stdin-filepath <path>  Path to the file to pretend that stdin comes from.
+  --support-info           Print support information as JSON.
   -v, --version            Print Prettier version.
 
 
@@ -634,6 +646,7 @@ Other options:
                            Defaults to false.
   --stdin                  Force reading input from stdin.
   --stdin-filepath <path>  Path to the file to pretend that stdin comes from.
+  --support-info           Print support information as JSON.
   -v, --version            Print Prettier version.
 
 

tests_integration/__tests__/__snapshots__/support-info.js.snap

@@ -0,0 +1,504 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`API getSupportInfo() no arguments 1`] = `
+Object {
+  "languages": Array [
+    Object {
+      "aceMode": "javascript",
+      "aliases": Array [
+        "js",
+        "node",
+      ],
+      "codemirrorMimeType": "text/javascript",
+      "codemirrorMode": "javascript",
+      "extensions": Array [
+        ".js",
+        "._js",
+        ".bones",
+        ".es",
+        ".es6",
+        ".frag",
+        ".gs",
+        ".jake",
+        ".jsb",
+        ".jscad",
+        ".jsfl",
+        ".jsm",
+        ".jss",
+        ".mjs",
+        ".njs",
+        ".pac",
+        ".sjs",
+        ".ssjs",
+        ".xsjs",
+        ".xsjslib",
+      ],
+      "filenames": Array [
+        "Jakefile",
+      ],
+      "group": "JavaScript",
+      "linguistLanguageId": 183,
+      "name": "JavaScript",
+      "parsers": Array [
+        "babylon",
+        "flow",
+      ],
+      "since": "0.0.0",
+      "tmScope": "source.js",
+      "vscodeLanguageIds": Array [
+        "javascript",
+      ],
+    },
+    Object {
+      "aceMode": "javascript",
+      "codemirrorMimeType": "text/jsx",
+      "codemirrorMode": "jsx",
+      "extensions": Array [
+        ".jsx",
+      ],
+      "group": "JavaScript",
+      "liguistLanguageId": 178,
+      "name": "JSX",
+      "parsers": Array [
+        "babylon",
+        "flow",
+      ],
+      "since": "0.0.0",
+      "tmScope": "source.js.jsx",
+      "vscodeLanguageIds": Array [
+        "javascriptreact",
+      ],
+    },
+    Object {
+      "aceMode": "typescript",
+      "aliases": Array [
+        "ts",
+      ],
+      "codemirrorMimeType": "application/typescript",
+      "codemirrorMode": "javascript",
+      "extensions": Array [
+        ".ts",
+        ".tsx",
+      ],
+      "group": "JavaScript",
+      "liguistLanguageId": 378,
+      "name": "TypeScript",
+      "parsers": Array [
+        "typescript",
+      ],
+      "since": "1.4.0",
+      "tmScope": "source.ts",
+      "vscodeLanguageIds": Array [
+        "typescript",
+        "typescriptreact",
+      ],
+    },
+    Object {
+      "aceMode": "css",
+      "codemirrorMimeType": "text/css",
+      "codemirrorMode": "css",
+      "extensions": Array [
+        ".css",
+      ],
+      "group": "CSS",
+      "liguistLanguageId": 50,
+      "name": "CSS",
+      "parsers": Array [
+        "css",
+      ],
+      "since": "1.4.0",
+      "tmScope": "source.css",
+      "vscodeLanguageIds": Array [
+        "css",
+      ],
+    },
+    Object {
+      "aceMode": "less",
+      "codemirrorMimeType": "text/css",
+      "codemirrorMode": "css",
+      "extensions": Array [
+        ".less",
+      ],
+      "group": "CSS",
+      "liguistLanguageId": 198,
+      "name": "Less",
+      "parsers": Array [
+        "less",
+      ],
+      "since": "1.4.0",
+      "tmScope": "source.css.less",
+      "vscodeLanguageIds": Array [
+        "less",
+      ],
+    },
+    Object {
+      "aceMode": "scss",
+      "codemirrorMimeType": "text/x-scss",
+      "codemirrorMode": "css",
+      "extensions": Array [
+        ".scss",
+      ],
+      "group": "CSS",
+      "liguistLanguageId": 329,
+      "name": "SCSS",
+      "parsers": Array [
+        "scss",
+      ],
+      "since": "1.4.0",
+      "tmScope": "source.scss",
+      "vscodeLanguageIds": Array [
+        "scss",
+      ],
+    },
+    Object {
+      "aceMode": "text",
+      "extensions": Array [
+        ".graphql",
+        ".gql",
+      ],
+      "liguistLanguageId": 139,
+      "name": "GraphQL",
+      "parsers": Array [
+        "graphql",
+      ],
+      "since": "1.5.0",
+      "tmScope": "source.graphql",
+      "vscodeLanguageIds": Array [
+        "graphql",
+      ],
+    },
+    Object {
+      "aceMode": "json",
+      "codemirrorMimeType": "application/json",
+      "codemirrorMode": "javascript",
+      "extensions": Array [
+        ".json",
+        ".json5",
+        ".geojson",
+        ".JSON-tmLanguage",
+        ".topojson",
+      ],
+      "filenames": Array [
+        ".arcconfig",
+        ".jshintrc",
+        ".babelrc",
+        ".eslintrc",
+        ".prettierrc",
+        "composer.lock",
+        "mcmod.info",
+      ],
+      "group": "JavaScript",
+      "linguistLanguageId": 174,
+      "name": "JSON",
+      "parsers": Array [
+        "json",
+      ],
+      "since": "1.5.0",
+      "tmScope": "source.json",
+      "vscodeLanguageIds": Array [
+        "json",
+      ],
+    },
+  ],
+}
+`;
+
+exports[`API getSupportInfo() with version 0.0.0 1`] = `
+Object {
+  "JSX": Array [
+    "babylon",
+    "flow",
+  ],
+  "JavaScript": Array [
+    "babylon",
+    "flow",
+  ],
+}
+`;
+
+exports[`API getSupportInfo() with version 1.0.0 1`] = `
+Object {
+  "JSX": Array [
+    "babylon",
+    "flow",
+  ],
+  "JavaScript": Array [
+    "babylon",
+    "flow",
+  ],
+}
+`;
+
+exports[`API getSupportInfo() with version 1.4.0 1`] = `
+Object {
+  "CSS": Array [
+    "postcss",
+  ],
+  "JSX": Array [
+    "babylon",
+    "flow",
+  ],
+  "JavaScript": Array [
+    "babylon",
+    "flow",
+  ],
+  "Less": Array [
+    "postcss",
+  ],
+  "SCSS": Array [
+    "postcss",
+  ],
+  "TypeScript": Array [
+    "typescript",
+  ],
+}
+`;
+
+exports[`API getSupportInfo() with version 1.5.0 1`] = `
+Object {
+  "CSS": Array [
+    "postcss",
+  ],
+  "GraphQL": Array [
+    "graphql",
+  ],
+  "JSON": Array [
+    "json",
+  ],
+  "JSX": Array [
+    "babylon",
+    "flow",
+  ],
+  "JavaScript": Array [
+    "babylon",
+    "flow",
+  ],
+  "Less": Array [
+    "postcss",
+  ],
+  "SCSS": Array [
+    "postcss",
+  ],
+  "TypeScript": Array [
+    "typescript",
+  ],
+}
+`;
+
+exports[`API getSupportInfo() with version 1.7.1 1`] = `
+Object {
+  "CSS": Array [
+    "css",
+  ],
+  "GraphQL": Array [
+    "graphql",
+  ],
+  "JSON": Array [
+    "json",
+  ],
+  "JSX": Array [
+    "babylon",
+    "flow",
+  ],
+  "JavaScript": Array [
+    "babylon",
+    "flow",
+  ],
+  "Less": Array [
+    "less",
+  ],
+  "SCSS": Array [
+    "scss",
+  ],
+  "TypeScript": Array [
+    "typescript",
+  ],
+}
+`;
+
+exports[`API getSupportInfo() with version 1.8.0 1`] = `
+Object {
+  "CSS": Array [
+    "css",
+  ],
+  "GraphQL": Array [
+    "graphql",
+  ],
+  "JSON": Array [
+    "json",
+  ],
+  "JSX": Array [
+    "babylon",
+    "flow",
+  ],
+  "JavaScript": Array [
+    "babylon",
+    "flow",
+  ],
+  "Less": Array [
+    "less",
+  ],
+  "Markdown": Array [
+    "markdown",
+  ],
+  "SCSS": Array [
+    "scss",
+  ],
+  "TypeScript": Array [
+    "typescript",
+  ],
+}
+`;
+
+exports[`CLI --support-info (stderr) 1`] = `""`;
+
+exports[`CLI --support-info (stdout) 1`] = `
+"{
+  \\"languages\\": [
+    {
+      \\"name\\": \\"JavaScript\\",
+      \\"since\\": \\"0.0.0\\",
+      \\"parsers\\": [\\"babylon\\", \\"flow\\"],
+      \\"group\\": \\"JavaScript\\",
+      \\"tmScope\\": \\"source.js\\",
+      \\"aceMode\\": \\"javascript\\",
+      \\"codemirrorMode\\": \\"javascript\\",
+      \\"codemirrorMimeType\\": \\"text/javascript\\",
+      \\"aliases\\": [\\"js\\", \\"node\\"],
+      \\"extensions\\": [
+        \\".js\\",
+        \\"._js\\",
+        \\".bones\\",
+        \\".es\\",
+        \\".es6\\",
+        \\".frag\\",
+        \\".gs\\",
+        \\".jake\\",
+        \\".jsb\\",
+        \\".jscad\\",
+        \\".jsfl\\",
+        \\".jsm\\",
+        \\".jss\\",
+        \\".mjs\\",
+        \\".njs\\",
+        \\".pac\\",
+        \\".sjs\\",
+        \\".ssjs\\",
+        \\".xsjs\\",
+        \\".xsjslib\\"
+      ],
+      \\"filenames\\": [\\"Jakefile\\"],
+      \\"linguistLanguageId\\": 183,
+      \\"vscodeLanguageIds\\": [\\"javascript\\"]
+    },
+    {
+      \\"name\\": \\"JSX\\",
+      \\"since\\": \\"0.0.0\\",
+      \\"parsers\\": [\\"babylon\\", \\"flow\\"],
+      \\"group\\": \\"JavaScript\\",
+      \\"extensions\\": [\\".jsx\\"],
+      \\"tmScope\\": \\"source.js.jsx\\",
+      \\"aceMode\\": \\"javascript\\",
+      \\"codemirrorMode\\": \\"jsx\\",
+      \\"codemirrorMimeType\\": \\"text/jsx\\",
+      \\"liguistLanguageId\\": 178,
+      \\"vscodeLanguageIds\\": [\\"javascriptreact\\"]
+    },
+    {
+      \\"name\\": \\"TypeScript\\",
+      \\"since\\": \\"1.4.0\\",
+      \\"parsers\\": [\\"typescript\\"],
+      \\"group\\": \\"JavaScript\\",
+      \\"aliases\\": [\\"ts\\"],
+      \\"extensions\\": [\\".ts\\", \\".tsx\\"],
+      \\"tmScope\\": \\"source.ts\\",
+      \\"aceMode\\": \\"typescript\\",
+      \\"codemirrorMode\\": \\"javascript\\",
+      \\"codemirrorMimeType\\": \\"application/typescript\\",
+      \\"liguistLanguageId\\": 378,
+      \\"vscodeLanguageIds\\": [\\"typescript\\", \\"typescriptreact\\"]
+    },
+    {
+      \\"name\\": \\"CSS\\",
+      \\"since\\": \\"1.4.0\\",
+      \\"parsers\\": [\\"css\\"],
+      \\"group\\": \\"CSS\\",
+      \\"tmScope\\": \\"source.css\\",
+      \\"aceMode\\": \\"css\\",
+      \\"codemirrorMode\\": \\"css\\",
+      \\"codemirrorMimeType\\": \\"text/css\\",
+      \\"extensions\\": [\\".css\\"],
+      \\"liguistLanguageId\\": 50,
+      \\"vscodeLanguageIds\\": [\\"css\\"]
+    },
+    {
+      \\"name\\": \\"Less\\",
+      \\"since\\": \\"1.4.0\\",
+      \\"parsers\\": [\\"less\\"],
+      \\"group\\": \\"CSS\\",
+      \\"extensions\\": [\\".less\\"],
+      \\"tmScope\\": \\"source.css.less\\",
+      \\"aceMode\\": \\"less\\",
+      \\"codemirrorMode\\": \\"css\\",
+      \\"codemirrorMimeType\\": \\"text/css\\",
+      \\"liguistLanguageId\\": 198,
+      \\"vscodeLanguageIds\\": [\\"less\\"]
+    },
+    {
+      \\"name\\": \\"SCSS\\",
+      \\"since\\": \\"1.4.0\\",
+      \\"parsers\\": [\\"scss\\"],
+      \\"group\\": \\"CSS\\",
+      \\"tmScope\\": \\"source.scss\\",
+      \\"aceMode\\": \\"scss\\",
+      \\"codemirrorMode\\": \\"css\\",
+      \\"codemirrorMimeType\\": \\"text/x-scss\\",
+      \\"extensions\\": [\\".scss\\"],
+      \\"liguistLanguageId\\": 329,
+      \\"vscodeLanguageIds\\": [\\"scss\\"]
+    },
+    {
+      \\"name\\": \\"GraphQL\\",
+      \\"since\\": \\"1.5.0\\",
+      \\"parsers\\": [\\"graphql\\"],
+      \\"extensions\\": [\\".graphql\\", \\".gql\\"],
+      \\"tmScope\\": \\"source.graphql\\",
+      \\"aceMode\\": \\"text\\",
+      \\"liguistLanguageId\\": 139,
+      \\"vscodeLanguageIds\\": [\\"graphql\\"]
+    },
+    {
+      \\"name\\": \\"JSON\\",
+      \\"since\\": \\"1.5.0\\",
+      \\"parsers\\": [\\"json\\"],
+      \\"group\\": \\"JavaScript\\",
+      \\"tmScope\\": \\"source.json\\",
+      \\"aceMode\\": \\"json\\",
+      \\"codemirrorMode\\": \\"javascript\\",
+      \\"codemirrorMimeType\\": \\"application/json\\",
+      \\"extensions\\": [
+        \\".json\\",
+        \\".json5\\",
+        \\".geojson\\",
+        \\".JSON-tmLanguage\\",
+        \\".topojson\\"
+      ],
+      \\"filenames\\": [
+        \\".arcconfig\\",
+        \\".jshintrc\\",
+        \\".babelrc\\",
+        \\".eslintrc\\",
+        \\".prettierrc\\",
+        \\"composer.lock\\",
+        \\"mcmod.info\\"
+      ],
+      \\"linguistLanguageId\\": 174,
+      \\"vscodeLanguageIds\\": [\\"json\\"]
+    }
+  ]
+}
+
+"
+`;
+
+exports[`CLI --support-info (write) 1`] = `Array []`;

tests_integration/__tests__/support-info.js

@@ -0,0 +1,30 @@
+"use strict";
+
+const prettier = require("../../tests_config/require_prettier");
+const runPrettier = require("../runPrettier");
+
+describe("API getSupportInfo()", () => {
+  test("no arguments", () => {
+    expect(prettier.getSupportInfo()).toMatchSnapshot();
+  });
+
+  const testVersions = ["0.0.0", "1.0.0", "1.4.0", "1.5.0", "1.7.1", "1.8.0"];
+
+  testVersions.forEach(version => {
+    test(`with version ${version}`, () => {
+      expect(
+        prettier
+          .getSupportInfo(version)
+          .languages.reduce(
+            (obj, language) =>
+              Object.assign({ [language.name]: language.parsers }, obj),
+            {}
+          )
+      ).toMatchSnapshot();
+    });
+  });
+});
+
+describe("CLI --support-info", () => {
+  runPrettier("cli", "--support-info").test({ status: 0 });
+});

tests_integration/__tests__/with-parser-inference.js

@@ -1,6 +1,7 @@
 "use strict";
 
 const runPrettier = require("../runPrettier");
+const prettier = require("../../tests_config/require_prettier");
 
 describe("infers postcss parser", () => {
   runPrettier("cli/with-parser-inference", ["*"]).test({
@@ -13,3 +14,17 @@ describe("infers postcss parser with --list-different", () => {
     status: 0
   });
 });
+
+describe("infers parser from filename", () => {
+  test("json from .prettierrc", () => {
+    expect(
+      prettier.format("  {   }  ", { filepath: "x/y/.prettierrc" })
+    ).toEqual("{}\n");
+  });
+
+  test("babylon from Jakefile", () => {
+    expect(
+      prettier.format("let foo = ( x = 1 ) => x", { filepath: "x/y/Jakefile" })
+    ).toEqual("let foo = (x = 1) => x;\n");
+  });
+});