refactor: extract validate option functions

src/cli-constant.js

@@ -1,6 +1,6 @@
 "use strict";
 
-const options = {
+const options = sortAndAddNameKey({
   "bracket-spacing": {
     type: "boolean",
     isFormatOption: true,
@@ -186,14 +186,12 @@ const options = {
     type: "boolean",
     description: "Edit the file in-place. (Beware!)"
   }
-};
+});
 
-const optionArray = Object.keys(options)
-  .sort()
-  .reduce(
-    (current, name) => current.concat(Object.assign({ name }, options[name])),
-    []
-  );
+const optionArray = Object.keys(options).reduce(
+  (current, name) => current.concat(options[name]),
+  []
+);
 
 const booleanOptionNames = optionArray
   .filter(option => option.isFormatOption && option.type === "boolean")
@@ -293,10 +291,21 @@ function dedent(str) {
   return str.replace(new RegExp(`^ {${spaces}}`, "gm"), "").trim();
 }
 
+function sortAndAddNameKey(obj) {
+  return Object.keys(obj)
+    .sort()
+    .reduce(
+      (current, name) =>
+        Object.assign(current, { [name]: Object.assign({ name }, obj[name]) }),
+      {}
+    );
+}
+
 module.exports = {
   booleanOptionNames,
   stringOptionNames,
   defaultOptions,
   minimistOptions,
+  options,
   usage
 };

src/cli-util.js

@@ -14,6 +14,7 @@ const prettier = eval("require")("../index");
 const cleanAST = require("./clean-ast").cleanAST;
 const resolver = require("./resolve-config");
 const constant = require("./cli-constant");
+const validator = require("./cli-validator");
 
 function getOptions(argv) {
   return {
@@ -53,20 +54,11 @@ function getParserOption(argv) {
 function getIntOption(argv, optionName) {
   const value = argv[optionName];
 
-  if (value === undefined) {
-    return value;
-  }
+  validator.validateIntOption(value, constant.options[optionName], {
+    exceptions: [undefined]
+  });
 
-  if (/^\d+$/.test(value)) {
-    return Number(value);
-  }
-
-  throw new Error(
-    "Invalid --" +
-      optionName +
-      " value.\nExpected an integer, but received: " +
-      JSON.stringify(value)
-  );
+  return value === undefined ? value : Number(value);
 }
 
 function getTrailingComma(argv) {
@@ -81,15 +73,9 @@ function getTrailingComma(argv) {
       return "es5";
     case undefined:
       return "none";
-    case "none":
-    case "es5":
-    case "all":
-      return value;
     default:
-      throw new Error(
-        "Invalid option for --trailing-comma.\n" +
-          `Expected "none", "es5" or "all", but received: "${value}"`
-      );
+      validator.validateChoiceOption(value, constant.options["trailing-comma"]);
+      return value;
   }
 }
 
@@ -232,6 +218,11 @@ function parseArgsToOptions(args, defaults) {
 
 function applyConfigPrecedence(args, options, configPrecedence) {
   try {
+    validator.validateChoiceOption(
+      configPrecedence,
+      constant.options["config-precedence"]
+    );
+
     switch (configPrecedence) {
       case "cli-override":
         return parseArgsToOptions(args, options);
@@ -239,13 +230,6 @@ function applyConfigPrecedence(args, options, configPrecedence) {
         return Object.assign({}, parseArgsToOptions(args), options);
       case "prefer-file":
         return options || parseArgsToOptions(args);
-
-      default:
-        throw new Error(
-          "Invalid option for --config-precedence.\n" +
-            'Expected "cli-override", "file-override" or "prefer-file", ' +
-            `but received: "${configPrecedence}"`
-        );
     }
   } catch (error) {
     console.error(error.toString());

src/cli-validator.js

@@ -12,6 +12,38 @@ function validateArgv(argv) {
   }
 }
 
+function validateIntOption(value, option, opts) {
+  if (opts && opts.exceptions && opts.exceptions.indexOf(value) !== -1) {
+    return;
+  }
+
+  if (!/^\d+$/.test(value)) {
+    throw new Error(
+      `Invalid --${option.name} value.\nExpected an integer, but received: ${value}`
+    );
+  }
+}
+
+function validateChoiceOption(value, option, opts) {
+  if (option.choices.indexOf(value) === -1) {
+    throw new Error(
+      `Invalid option for --${option.name}.\nExpected ${getJoinedChoices()}, but received: "${value}"`
+    );
+  }
+
+  function getJoinedChoices() {
+    const choices = option.choices.map(choice => `"${choice}"`);
+    if (choices.length === 1) {
+      return choices[0];
+    }
+    const head = choices.slice(0, -2);
+    const tail = choices.slice(-2);
+    return head.concat(tail.join(" or ")).join(", ");
+  }
+}
+
 module.exports = {
-  validateArgv
+  validateArgv,
+  validateIntOption,
+  validateChoiceOption
 };