Code coverage or No test coverage issue in Salesforce

Some people's say, I have wrote test classes but not getting code coverage. In this occasion, try the below steps. It might solve your problem.

Step 1: 

Ensure your test class declared with correct annotation,

1. Test class should start with @isTest annotation.
2. Methods should declared as testMethod or @isTest annotation.

1. @isTest
2. private class MyTestClass {
4.    // Methods for testing
5.    static testMethod void test1() {
6.       // Implement test code
7.    }
9.    @isTest static void test2() {
10.       // Implement test code
11.    }
13. }

Step 2: 

Go to Setup --> Build --> Develop --> Apex Test Execution -->  Options --> Disable Parallel Apex Testing

Ensure "Disable Parallel Apex Testing" check box is checked.

Note: Try the below solution if you received an error as "UNABLE_TO_LOCK_ROW, unable to obtain exclusive access to this record"

Step 3: 

Go to Setup --> Build --> Develop --> Apex Test Execution -->  View Test History--> Clear all data

Step 4:

Go to Setup --> Build -->  Develop --> Apex Test Execution -->  Select Test --> Run