Add --print-config CLI flag (fixes #3127) (#3532)

docs/user-guide/cli.md

@@ -104,6 +104,10 @@ If you're using both these special comments and autofixing, please run stylelint
 
 For CSS with standard syntax, stylelint will use [postcss-safe-parser](https://github.com/postcss/postcss-safe-parser) to fix syntax errors.
 
+### Troubleshooting configurations
+
+With the `--print-config` option, stylelint outputs the configuration to be used for the file passed. When present, no linting is performed and only config-related options are valid.
+
 ## Syntax errors
 
 The CLI informs you about syntax errors in your CSS.

flow-typed/stylelint.js

@@ -137,6 +137,7 @@ export type stylelint$standaloneOptions = {
   configFile?: string,
   configBasedir?: string,
   configOverrides?: Object,
+  printConfig?: string,
   ignoreDisables?: boolean,
   ignorePath?: string,
   ignorePattern?: RegExp,

lib/__tests__/printConfig.test.js

@@ -0,0 +1,64 @@
+"use strict";
+
+const path = require("path");
+const pluginWarnAboutFoo = require("./fixtures/plugin-warn-about-foo");
+const printConfig = require("../printConfig");
+
+it("printConfig uses getConfigForFile to retrieve the config", () => {
+  const filepath = path.join(
+    __dirname,
+    "fixtures/getConfigForFile/a/b/foo.css"
+  );
+  printConfig({
+    files: [filepath]
+  }).then(result => {
+    expect(result).toEqual({
+      plugins: [path.join(__dirname, "/fixtures/plugin-warn-about-foo.js")],
+      rules: {
+        "block-no-empty": [true],
+        "plugin/warn-about-foo": ["always"]
+      },
+      pluginFunctions: {
+        "plugin/warn-about-foo": pluginWarnAboutFoo.rule
+      }
+    });
+  });
+});
+
+it("printConfig with input css should throw", () => {
+  expect(
+    printConfig({
+      code: "a {}"
+    })
+  ).rejects.toThrow(
+    "The --print-config option must be used with exactly one file path."
+  );
+});
+
+it("printConfig with no path should throw", () => {
+  expect(
+    printConfig({
+      files: []
+    })
+  ).rejects.toThrow(
+    "The --print-config option must be used with exactly one file path."
+  );
+});
+
+it("printConfig with multiple paths should throw", () => {
+  expect(
+    printConfig({
+      files: ["./first-path.css", "./second-path.css"]
+    })
+  ).rejects.toThrow(
+    "The --print-config option must be used with exactly one file path."
+  );
+});
+
+it("printConfig with globs should throw", () => {
+  expect(
+    printConfig({
+      files: ["./*.css"]
+    })
+  ).rejects.toThrow("The --print-config option does not support globs.");
+});

lib/cli.js

@@ -10,6 +10,7 @@ const getStdin = require("get-stdin");
 const meow = require("meow");
 const needlessDisablesStringFormatter = require("./formatters/needlessDisablesStringFormatter");
 const path = require("path");
+const printConfig = require("./printConfig");
 const resolveFrom = require("resolve-from");
 const standalone = require("./standalone");
 
@@ -32,6 +33,9 @@ const standalone = require("./standalone");
     "config-basedir": {
       type: string
     },
+    "print-config": {
+      type: string
+    },
     color: {
       type: string
     },
@@ -101,6 +105,7 @@ const standalone = require("./standalone");
     cacheLocation: any,
     config: any,
     configBasedir: any,
+    printConfig: boolean,
     customFormatter: any,
     customSyntax: any,
     disableDefaultIgnores: boolean,
@@ -136,6 +141,7 @@ const standalone = require("./standalone");
   configOverrides: {
     quiet?: any,
   },
+  printConfig?: any,
   customSyntax?: any,
   fix?: any,
   ignoreDisables?: any,
@@ -181,6 +187,10 @@ const meowOptions /*: meowOptionsType*/ = {
         and "plugins" are *relative to*. Only necessary if these values are
         relative paths.
 
+      --print-config
+
+        Print the configuration for the given path.
+
       --ignore-path, -i
 
         Path to a file containing patterns that describe files to ignore. The
@@ -280,6 +290,9 @@ const meowOptions /*: meowOptionsType*/ = {
     "config-basedir": {
       type: "string"
     },
+    "print-config": {
+      type: "boolean"
+    },
     color: {
       type: "boolean"
     },
@@ -462,6 +475,14 @@ module.exports = (argv /*: string[]*/) /*: Promise<void>|void*/ => {
       );
     })
     .then(options => {
+      if (cli.flags.printConfig) {
+        return printConfig(options)
+          .then(config => {
+            process.stdout.write(JSON.stringify(config, null, "  "));
+          })
+          .catch(handleError);
+      }
+
       if (!options.files && !options.code) {
         cli.showHelp();
         return;
@@ -500,10 +521,12 @@ module.exports = (argv /*: string[]*/) /*: Promise<void>|void*/ => {
             process.exitCode = 2;
           }
         })
-        .catch((err /*: { stack: any, code: any }*/) => {
-          console.log(err.stack); // eslint-disable-line no-console
-          const exitCode = typeof err.code === "number" ? err.code : 1;
-          process.exit(exitCode); // eslint-disable-line no-process-exit
-        });
+        .catch(handleError);
     });
 };
+
+function handleError(err /*: { stack: any, code: any }*/) /*: void */ {
+  console.log(err.stack); // eslint-disable-line no-console
+  const exitCode = typeof err.code === "number" ? err.code : 1;
+  process.exit(exitCode); // eslint-disable-line no-process-exit
+}

lib/printConfig.js

@@ -0,0 +1,54 @@
+/* @flow */
+"use strict";
+
+const _ = require("lodash");
+const createStylelint = require("./createStylelint");
+const globby /*: Function*/ = require("globby");
+const path = require("path");
+
+module.exports = function(
+  options /*: stylelint$standaloneOptions */
+) /*: Promise<stylelint$config>*/ {
+  const code = options.code;
+  const config = options.config;
+  const configBasedir = options.configBasedir;
+  const configFile = options.configFile;
+  const configOverrides = options.configOverrides;
+  const globbyOptions = options.globbyOptions;
+  const files = options.files;
+
+  const isCodeNotFile = code !== undefined;
+  if (!files || files.length !== 1 || isCodeNotFile) {
+    return Promise.reject(
+      new Error(
+        "The --print-config option must be used with exactly one file path."
+      )
+    );
+  }
+
+  const filePath = files[0];
+
+  if (globby.hasMagic(filePath)) {
+    return Promise.reject(
+      new Error("The --print-config option does not support globs.")
+    );
+  }
+
+  const stylelint = createStylelint({
+    config,
+    configFile,
+    configBasedir,
+    configOverrides
+  });
+
+  const cwd = _.get(globbyOptions, "cwd", process.cwd());
+  const absoluteFilePath = !path.isAbsolute(filePath)
+    ? path.join(cwd, filePath)
+    : path.normalize(filePath);
+
+  const configSearchPath = stylelint._options.configFile || absoluteFilePath;
+
+  return stylelint
+    .getConfigForFile(configSearchPath)
+    .then(result => result.config);
+};

system-tests/cli/cli.test.js

@@ -1,6 +1,7 @@
 /* eslint no-console: off */
 "use strict";
 const cli = require("../../lib/cli");
+const path = require("path");
 const pkg = require("../../package.json");
 
 jest.mock("get-stdin");
@@ -23,6 +24,7 @@ describe("CLI", () => {
   beforeEach(function() {
     process.exitCode = undefined;
     console.log = jest.fn();
+    process.stdout.write = jest.fn();
     if (parseInt(process.versions.node) < 7) {
       // https://github.com/sindresorhus/get-stdin/issues/13
       process.nextTick(() => {
@@ -60,4 +62,29 @@ describe("CLI", () => {
       expect(lastCallArgs.pop()).toMatch(pkg.version);
     });
   });
+
+  it("--print-config", () => {
+    return Promise.resolve(
+      cli([
+        "--print-config",
+        "--config",
+        path.join(__dirname, "config.json"),
+        path.join(__dirname, "stylesheet.css")
+      ])
+    ).then(() => {
+      expect(process.exitCode).toBe(undefined);
+      expect(process.stdout.write).toHaveBeenCalledTimes(1);
+      expect(process.stdout.write).toHaveBeenLastCalledWith(
+        JSON.stringify(
+          {
+            rules: {
+              "block-no-empty": [true]
+            }
+          },
+          null,
+          "  "
+        )
+      );
+    });
+  });
 });

system-tests/cli/config.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "block-no-empty": true
+  }
+}