Merge pull request #95 from bem-sdk/fix/type-error

Refactor of TypeError

Author: blond

README.md

@@ -57,39 +57,33 @@ BEM entities can be defined with a help of JS object with the following fields:
 
 The modifier consists of a pair of fields `mod.name` and `mod.val`. This means that the field `mod.val` without `mod.name` has no meaning.
 
-**Example:**
-
 ```js
 const BemEntityName = require('@bem/entity-name');
 
 // The modifier of block
 new BemEntityName({
     block: 'button',
-    mod: { name 'view', val: 'action' }
+    mod: { name: 'view', val: 'action' }
 });
 
 // Not valid modifier
 new BemEntityName({
-    block: 'block',
+    block: 'button',
     mod: { val: 'action' }
 });
+// ➜ EntityTypeError: the object `{ block: 'block', mod: { val: 'action' } }` is not valid BEM entity, the field `mod.name` is undefined
 ```
 
-To describe the simple modifier, field `mod.val` must be specified as `true`.
-
-**Example:**
+To describe a simple modifier the `mod.val` field must be omitted.
 
 ```js
-// Boolean modifier of a block
-new BemEntityName({
-    block: 'button',
-    mod: { name: 'focused', val: true }
-});
+// Simple modifier of a block
+new BemEntityName({ block: 'button', mod: 'focused' });
 
-// Shorthand for the boolean modifier of a block
+// Is equivalent to simple modifier, if `mod.val` is `true`
 new BemEntityName({
     block: 'button',
-    mod: 'focused'
+    mod: { name: 'focused', val: true }
 });
 ```
 

index.js

@@ -17,17 +17,19 @@ const TYPES = {
     ELEM:      'elem',
     ELEM_MOD:  'elemMod'
 };
-
-class NotValidEntityError extends ExtendableError {
+/**
+ * The EntityTypeError object represents an error when a value is not valid BEM entity.
+ */
+class EntityTypeError extends ExtendableError {
     /**
      * @param {object} obj — not valid object
-     * @param {str} [reason] — reason why object is not valid
+     * @param {string} [reason] — human-readable reason why object is not valid
      */
     constructor(obj, reason) {
         const str = util.inspect(obj, { depth: 1 });
-        const message = `The object \`${str}\` is not valid BEM entity`;
+        const message = `the object \`${str}\` is not valid BEM entity`;
 
-        super(reason ? `${message}: ${reason}` : message);
+        super(reason ? `${message}, ${reason}` : message);
     }
 }
 
@@ -45,7 +47,7 @@ module.exports = class BemEntityName {
      */
     constructor(obj) {
         if (!obj.block) {
-            throw new NotValidEntityError(obj, 'the field `block` is undefined');
+            throw new EntityTypeError(obj, 'the field `block` is undefined');
         }
 
         const data = this._data = { block: obj.block };
@@ -62,7 +64,7 @@ module.exports = class BemEntityName {
                 val: hasModVal ? modObj && modObj.val || obj.modVal : true
             };
         } else if (modObj || hasModVal) {
-            throw new NotValidEntityError(obj, 'the field `mod.name` is undefined');
+            throw new EntityTypeError(obj, 'the field `mod.name` is undefined');
         }
 
         this.__isBemEntityName__ = true;

test/construct.test.js

@@ -29,20 +29,20 @@ test('should create object and normalize boolean modifier', t => {
 test('should throw error for if entity object is not valid', t => {
     t.throws(
         () => new BemEntityName({ elem: 'elem' }),
-        "The object `{ elem: 'elem' }` is not valid BEM entity: the field `block` is undefined"
+        "the object `{ elem: 'elem' }` is not valid BEM entity, the field `block` is undefined"
     );
 });
 
 test('should throw error for if mod object is empty', t => {
     t.throws(
         () => new BemEntityName({ block: 'block', mod: {} }),
-        "The object `{ block: 'block', mod: {} }` is not valid BEM entity: the field `mod.name` is undefined"
+        "the object `{ block: 'block', mod: {} }` is not valid BEM entity, the field `mod.name` is undefined"
     );
 });
 
 test('should throw error for if mod name is undefined', t => {
     t.throws(
         () => new BemEntityName({ block: 'block', mod: { val: 'val' } }),
-        "The object `{ block: 'block', mod: { val: 'val' } }` is not valid BEM entity: the field `mod.name` is undefined"
+        "the object `{ block: 'block', mod: { val: 'val' } }` is not valid BEM entity, the field `mod.name` is undefined"
     );
 });