docs: typo and brevity (#1097)

Author: lukeingalls

src/guide/testing.md

@@ -58,7 +58,7 @@ Mocha is a JavaScript test framework that is focused on being flexible. Because
 
 ### Introduction
 
-To test most Vue components, they must be mounted to the DOM (either virtual or real) in order to fully assert that they are working. This is another framework-agnostic concept. As a result, component testing frameworks were created to give users the ability to do this in a reliable way while also providing Vue-specific conveniences such as integrations for Vuex, Vue Router, and other Vue plugins.
+To test most Vue components, they must be mounted to the DOM (either virtual or real) in order to fully assert that they are working. This is another framework-agnostic concept. As a result, component testing frameworks were created to give users the ability to do this reliably while also providing Vue-specific conveniences such as integrations for Vuex, Vue Router, and other Vue plugins.
 
 ### Choosing Your Framework
 
@@ -70,7 +70,7 @@ It should be no surprise that one of the first criteria is that a component test
 
 #### First-class error reporting
 
-When tests fail, it is critical that your component testing framework provides useful error logs that help to minimize the amount of time it takes to debug the problem. In addition to simply telling you what test fails, they should also provides context for why a test fails, e.g., what is expected vs what was received.
+When tests fail, it is critical that your component testing framework provides useful error logs that help to minimize the amount of time it takes to debug the problem. In addition to simply telling you what test fails, they should also provide context for why a test fails, e.g., what is expected vs what was received.
 
 ### Recommendations