feat: Added strict mode

index.js

@@ -1,18 +1,22 @@
-// TODO consider Guad instead
 class Acl {
-  constructor() {
+
+  /**
+   * constructor
+   *
+   * @access public
+   * @param {Boolean} {strict=false}={} Errors out on unknown verbs when true
+   * @returns {Acl}
+   */
+  constructor({strict = false} = {}) {
+    this.strict = strict
     this.rules = new Map()
     this.policies = new Map()
-    this.subjectMapper = subject => {
-      if (typeof subject === 'string') { return subject }
-      return typeof subject === 'function'
-        ? subject.name
-        : subject.constructor.name
-    }
   }
 
   /**
-   * mixin
+   * Mix in augments your user class with a `can` function. This
+   * is optional and you can always cann `can` directly on your
+   * Acl instance.
    *
    * @access public
    * @param {Object} userClass A user class or contructor function
@@ -24,32 +28,114 @@ class Acl {
     }
   }
 
+
+  /**
+   * Rules are grouped by subjects and this default mapper tries to
+   * map any non falsy input to a subject name.
+   *
+   * This is important when you want to try a verb against a rule
+   * passing in an instance of a class.
+   *
+   * - strings becomes subjects
+   * - function's names are used for subject
+   * - objects's constructor name is used for subject
+   *
+   * Override this function if your models do not match this approach.
+   *
+   * E.g. say that you are using plain data objects with a type property
+   * to indicate the "class" of the object.
+   *
+   *   acl.subjectMapper = subject => subject.type
+   *
+   * `can` will now use this function when you pass in your objects.
+   *
+   * @access public
+   * @param {Function|Object|string} subject
+   * @returns {string} A subject
+   */
+  subjectMapper(subject) {
+    if (typeof subject === 'string') { return subject }
+    return typeof subject === 'function'
+      ? subject.name
+      : subject.constructor.name
+  }
+
   /**
-   * rule
+   * You add rules by providing a verb, a subject and an optional
+   * test (that otherwise defaults to true).
+   *
+   * If the test is a function it will be evaluated with the params:
+   * user, subject, and subjectName. The test value is ultimately evaluated
+   * for thruthiness.
    *
    * @access public
    * @param {Array<string>|string} verbs
    * @param {Function|Object|string} subject
    * @param {Boolean} test=true
+   * @returns {Acl}
    */
   rule(verbs, subject, test = true) {
+    const subjectName = this.subjectMapper(subject)
     const verbs_ = Array.isArray(verbs) ? verbs : [verbs]
-    const subject_ = this.subjectMapper(subject)
     verbs_.forEach(verb => {
-      const rules = this.rules.get(subject_) || {}
+      const rules = this.rules.get(subjectName) || {}
       rules[verb] = test
-      this.rules.set(subject_, rules)
+      this.rules.set(subjectName, rules)
     })
     return this
   }
 
+  /**
+   * You can group related rules into policies for a subject. The policies
+   * properties are verbs and they can plain values or functions.
+   *
+   * If the policy is a function it will be new'ed up before use.
+   *
+   * class Post {
+   *   constructor() {
+   *     this.view = true       // no need for a functon
+   *
+   *     this.delete = false    // not really necessary since an abscent
+   *                            // verb has the same result
+   *   },
+   *   edit(user, subject) {
+   *     return subject.id === user.id
+   *   }
+   * }
+   *
+   * Policies are useful for grouping rules and adding more comples logic.
+   *
+   * @access public
+   * @param {Object} policy A policy with properties that are verbs
+   * @param {Function|Object|string} subject
+   * @returns {Acl}
+   */
   policy(policy, subject) {
+    const policy_ = typeof policy === 'function' ? new policy() : policy
     const subject_ = this.subjectMapper(subject)
     this.policies.set(subject_, policy)
+    return this
   }
 
   /**
-   * can
+   * Performs a test if a user can perform action on subject.
+   *
+   * The action is a verb and the subject can be anything the
+   * subjectMapper can map to a subject name.
+   *
+   * E.g. if you can to test if a user can delete a post you would
+   * pass the actual post. Where as if you are testing us a user
+   * can create a post you would pass the class function or a
+   * string.
+   *
+   *   acl->can(user, 'create', Post)
+   *   acl->can(user, 'edit', post)
+   *
+   * Note that these are also available on the user if you've used
+   * the mixin:
+   *
+   *   user->can('create', Post)
+   *   user->can('edit', post)
    *
    * @access public
    * @param {Object} user
@@ -63,6 +149,11 @@ class Acl {
     if (typeof rules[verb] === 'function') {
       return Boolean(rules[verb](user, subject, subject_))
     }
+
+    if (this.strict && typeof rules[verb] === 'undefined') {
+      throw new Error(`Unknown verb "${verb}"`)
+    }
+
     return Boolean(rules[verb])
   }
 }

test/Acl.test.js

@@ -54,6 +54,13 @@ test('Can eat apples (Object)', () => {
   expect(user.can('eat', new Apple())).toBe(true)
 })
 
+test('Throws on strict', () => {
+  const acl = new Acl({strict: true})
+  acl.mixin(User)
+  const user = new User()
+  expect(user.can.bind(user, 'eat', new Apple())).toThrow('Unknown verb "eat"')
+})
+
 test('Can create jobs complex', () => {
   const acl = new Acl()
   acl.mixin(User)