Fix to-have-length when there are no argument properties (#6)

* Fix to-have-length when there are no argument properties

* Support both `toBe` and `toEqual` in prefer-to-have-length

* Group argument and property together

Author: SimenB

rules/__tests__/prefer_to_have_length.test.js

@@ -6,7 +6,11 @@ const rules = require('../..').rules;
 const ruleTester = new RuleTester();
 
 ruleTester.run('prefer_to_have_length', rules['prefer-to-have-length'], {
-  valid: ['expect(files).toHaveLength(1);', "expect(files.name).toBe('file');"],
+  valid: [
+    'expect(files).toHaveLength(1);',
+    "expect(files.name).toBe('file');",
+    'expect(result).toBe(true);',
+  ],
 
   invalid: [
     {
@@ -20,5 +24,16 @@ ruleTester.run('prefer_to_have_length', rules['prefer-to-have-length'], {
       ],
       output: 'expect(files).toHaveLength(1);',
     },
+    {
+      code: 'expect(files.length).toEqual(1);',
+      errors: [
+        {
+          message: 'Use toHaveLength() instead',
+          column: 22,
+          line: 1,
+        },
+      ],
+      output: 'expect(files).toHaveLength(1);',
+    },
   ],
 });

rules/prefer_to_have_length.js

@@ -17,7 +17,11 @@ module.exports = context => {
         const argumentObject = node.arguments[0].object;
         const argumentProperty = node.arguments[0].property;
 
-        if (propertyName === 'toBe' && argumentProperty.name === 'length') {
+        if (
+          (propertyName === 'toBe' || propertyName === 'toEqual') &&
+          argumentProperty &&
+          argumentProperty.name === 'length'
+        ) {
           const propertyDot = context
             .getSourceCode()
             .getFirstTokenBetween(