Added more information in Mutation Test Readme

python/servo/mutation/README.md

@@ -5,7 +5,7 @@ The motivation for mutation testing is to test the breadth coverage of tests for
 
 For more info refer [Wiki page](https://en.wikipedia.org/wiki/Mutation_testing).
 
-In this project, mutation testing is used to test the coverage of WPT for Servo's browsing engine.
+Here Mutation testing is used to test the coverage of WPT for Servo's browsing engine.
 
 ### Mutation Strategy
 This version of mutation testing consists of a Python script that finds random uses of && in Servo's code base and replaces them by ||. The expectation from the WPT tests is to catch this mutation and result in failures when executed on the corresponding code base.
@@ -16,7 +16,7 @@ The mutation test aims to run only tests which are concerned with the mutant. Th
 #### test_mapping.json
 The file test_mapping.json is used to map the source code to their corresponding WPT tests. The user must maintain a updated version of this file in the path where mutation testing needs to be performed. Additionally, the test_mapping.json will only consist of maps of source codes that are present in the current directory. Hence, each folder will have a unique test_mapping.json file. Any source code files that may be present in a path but are not mapped to a WPT in test_mapping.json will not be covered for mutation testing.
 
-### Sample test_mapping.json format
+#### Sample test_mapping.json format
 A sample of test_mapping.json is as shown below:
 
 ```
@@ -32,14 +32,14 @@ A sample of test_mapping.json is as shown below:
 
 Please ensure that each folder that requires a mutant to be generated consists of test_mapping.json file so that the script can function as expected.
 
-### Basic Execution Flow
-The implementation of mutation testing is as follows:
-1. The script is called from the command line, it searches through the path entered by user for test_mapping.json.
-2. If found, it reads the json file and parses one componenent of source file to generate mutants. 
-3. The corresponding WPT tests are run for each mutant and the test results are logged.
-4. Once all WPT are run for the first source file, the mutation continues for other source files mentioned in the json file and runs their corresponding WPT tests.
-5. Once it has completed executing mutation testing for the entered path, it repeats the above procedure for sub-paths present inside the entered path.
+If we want to run mutation test for a source path then there should be test_mapping.json in that path and all the subdirectories which has source files.
 
+Eg: There should be test mapping in following folders if we run mutation test on 'components/script' path.
+* components/script/test_mapping.json
+* components/script/dom/test_mapping.json
+* components/script/task_source/test_mapping.json
+* components/script/dom/bindings/test_mapping.json
+* ...
 
 ### Running Mutation test
 The mutation tests can be run by running the below command from the servo directory on the command line interface:
@@ -52,4 +52,12 @@ Eg. `python python/servo/mutation/init.py components/script/dom`
 
 The CI script for running mutation testing is present in /etc/ci folder. It can be called by executing the below command from the CLI:
 
-`python /etc/ci/mutation_test.py`
+`python /etc/ci/mutation_test.py`
+
+### Execution Flow
+1. The script is called from the command line, it searches for test_mapping.json in the path entered by user.
+2. If found, it reads the json file and parses it, gets source file to tests mapping.
+3. If the source file does not have any local changes then it is mutated at a random line.
+4. The corresponding WPT tests are run for this mutant and the test results are logged.
+5. Once all WPT are run for the first source file, the mutation continues for other source files mentioned in the json file and runs their corresponding WPT tests.
+6. Once it has completed executing mutation testing for the entered path, it repeats the above procedure for sub-paths present inside the entered path.

python/servo/mutation/test.py

@@ -61,4 +61,4 @@ def mutation_test(file_name, tests):
             subprocess.call('git checkout {0}'.format(file_name), shell=True)
         else:
             print "Cannot mutate {0}".format(file_name)
-        print "-----------------------------------------------------------------\n"
+        print "-"*80 + "\n"