fix(command)!: commands will throw when duplicate short hands are found

Previously it was possible to define multiple flags with the same
shorthand which causes indeterminate behavior when using them. Now a
command class will throw an exception when this situation is encountered

fixes: #113

examples/commands/hello.js

@@ -25,7 +25,7 @@ module.exports = new cli.Command({
 
   , excited: {
       'type': Boolean
-    , 'shorthand': 'e'
+    , 'shorthand': 'n'
     , 'description': 'Say hello in a very excited manner'
     , 'default': false
     }

examples/commands/password-confirm.js

@@ -1,4 +1,4 @@
-'use strict'
+'puse strict'
 
 const cli = require('seeli')
 

lib/command/index.js

@@ -166,6 +166,7 @@ class Command extends Registry {
 
     this.setOptions(defaults, ...options)
 
+    this._shcache = this.shorthands
     this.ui = ora({
       color: conf.get('color')
     , spinner: this.options.ui
@@ -273,7 +274,17 @@ class Command extends Registry {
     this._shcache = Object.create(null)
 
     for (const [key, value] of Object.entries(this.options.flags)) {
-      if (value.shorthand) this._shcache[value.shorthand] = [`--${key}`]
+      if (value.shorthand) {
+        if (hasOwn(this._shcache, value.shorthand)) {
+          const [previous] = this._shcache[value.shorthand]
+          throw new exceptions.DuplicateShorthandException(
+            value.shorthand
+          , key
+          , previous.replace('--', '')
+          )
+        }
+        this._shcache[value.shorthand] = [`--${key}`]
+      }
     }
 
     return this._shcache
@@ -287,7 +298,7 @@ class Command extends Registry {
     const error = new exceptions.InvalidFieldException(
       `Invalided Field Value for ${chalk.yellow(key)} - ${msg}`
     )
-    this.emit('error', error)
+    throw error
   }
 
   /**
@@ -472,7 +483,7 @@ class Command extends Registry {
       if (stop_flags.has(flag)) continue
       const validator = cfg.validate
       const value = this.parsed[flag]
-      const choices = new Set(toArray(cfg.choices))
+      const choices = getChoices(cfg, this.parsed, value)
 
       this.debug('validating %s', flag)
       if (this._required.has(flag) && value === UNDEF) {
@@ -639,4 +650,16 @@ function toQuestion(flag, opts, answers) {
   return arg
 }
 
-
+function getChoices(cfg, answers) {
+  return new Set(
+    toArray(cfg.choices)
+      .filter((choice) => {
+        if (choice.type === 'separator') return false
+        return true
+      })
+      .map((choice) => {
+        if (typeOf(choice) === 'object') return choice.value
+        return choice
+      })
+  )
+}

lib/exceptions.js

@@ -1,4 +1,3 @@
-/* jshint laxcomma: true, smarttabs: true, node: true, esnext: true*/
 'use strict'
 /**
  * Default exception types for seeli
@@ -156,6 +155,43 @@ class UnknownFlagException extends Error {
   }
 }
 
+/**
+ * @class module:seeli/lib/exceptions.DuplicateShorthandException
+ * @param {String} field Name of the erroneous flag
+ * @extends Error
+ */
+class DuplicateShorthandException extends Error {
+  constructor(shorthand, flag, prev) {
+    super()
+
+    /**
+     * @readonly
+     * @instance
+     * @memberof module:seeli/lib/exceptions.DuplicateShorthandException
+     * @name name
+     * @property {String} name=DuplicateShorthandException Exception name
+     **/
+    this.name = 'DuplicateShorthandException'
+    /**
+     * @readonly
+     * @instance
+     * @memberof module:seeli/lib/exceptions.DuplicateShorthandException
+     * @name message
+     * @property {String} message Message to include in error output
+     **/
+    this.message = `shorthand ${shorthand} for flag ${flag} `
+      + `- duplicates flag ${prev}`
+    /**
+     * @readonly
+     * @instance
+     * @memberof module:seeli/lib/exceptions.UnkownFlagException
+     * @name code
+     * @property {String} message A Unique error code identifier
+     **/
+    this.code = 'ESHORTHAND'
+  }
+}
+
 class CommandException extends Error {
   constructor(msg) {
     super()
@@ -218,6 +254,7 @@ class PluginException extends Error {
 
 module.exports = {
   RequiredFieldException: RequiredFieldException
+, DuplicateShorthandException: DuplicateShorthandException
 , InvalidChoiceException: InvalidChoiceException
 , InvalidFieldException: InvalidFieldException
 , UnknownFlagException: UnknownFlagException

test/command.js

@@ -13,8 +13,8 @@ const test = require('tap').test
 test('command', async (t) => {
 
   // description parsing
-  t.test('~description', async (tt) => {
-    test('should accept a single string', async (t) => {
+  t.test('~description', async (t) => {
+    t.test('should accept a single string', async (t) => {
       const DescriptionCommand = new Command({
         description: 'a test command'
       })
@@ -28,6 +28,25 @@ test('command', async (t) => {
     })
   })
 
+  t.test('duplicate shorthands', async (t) => {
+    t.throws(() => {
+      return new Command({
+        flags: {
+          foo: {
+            type: String
+          , description: 'this is foo'
+          , shorthand: 'f'
+          }
+        , bar: {
+            type: String
+          , description: 'this is bar'
+          , shorthand: 'f'
+          }
+        }
+      })
+    }, {code: 'ESHORTHAND', name: 'DuplicateShorthandException'})
+  })
+
   t.test('nested flags', async (t) => {
     t.plan(3)
     const NestedCommand = new Command({
@@ -738,12 +757,12 @@ test('command', async (t) => {
     t.deepEqual(cmd.tree, {
       '-': base_flags
     , '--': base_flags
-    , two: {
-        three: base_flags
+    , 'two': {
+        'three': base_flags
       , '-': base_flags
       , '--': base_flags
       }
-    , one: [...base_flags, '--option', '--single']
+    , 'one': [...base_flags, '--option', '--single']
     }, 'serialized command tree')
   })