alanwuha / spring-test-writer

Generate test cases for spring applications

Spring Test Writer

One fine Saturday evening as I was eating my Mee Hoon Kuay at Old Airport Road Food Centre, I randomly recalled the 1195 lines of uncovered test cases for which I had to write test cases for in my current sprint.

Then, a brilliant idea came to mind (if I say so myself, lol).

Write a script to scan for java classes and generate test files and methods. A bonus if the automatically generated test cases could run and provide 100% coverage without any correction.

How To Run

Virtualenv

$ virtualenv env
$ source env/bin/activate

Pip

$ pip install -r requirements.txt

Run

$ python generate.py --src /home/userid/projects/helloworld/src

Components

1. FileScanner: Scans for .java files from a given directory
2. ClassFileParser: Parses .java file content into a ClassFile Object
3. TestFileGenerator: Generates test file in .java format from a ClassFile object

FileScanner

Recursively scan for .java files from a given root directory and return the list of class files.

ClassFileParser

Reads and parses the content of a class file into a ClassFile object.

1. Read content of .java file
2. Identify package
3. Identify class name
4. Scan for member variables
5. Scan for methods

Identify package

1. package code must be the first non-empty line in content
2. Line begins with the keyword package, followed by the package path and ends with a semicolon

Identify class name

Find the first line that follows the syntax:

[<access_modifier> ][<other_keywords> ]class <class_name>[ <extends_or_implements_class>][ {]

e.g.

public class HelloWorld {
public abstract class Hello {
public interface HelloInterface {
public class HelloWorld extends Hello {
public class HelloWorld implements HelloInterface {
public class HelloWorld extends Hello implements HelloInterface {
public static class HelloWorld<Hello, World> {

Extraction steps:

1. Replace string , with ,
2. Split string by consecutive spaces into a list
3. The element after the class element should be the class name

Additional Notes:

• If the class is an abstract class or an interface, then the test file cannot be generated since it cannot be instantiated.

Scan for member variables

Member variables generally follow the syntax:

[<access_modifier> ][<other_keywords> ]<data_type> <variable_name>[ = <RHS>];

e.g.

Object object;
int i = 0;
private String name;
protected Map<String, Object> map = new HashMap<>();
public static final int JANUARY = 1;

Extraction steps:

1. Replace string , with ,
2. Split string by consecutive spaces into a list
3. Remove keywords from list: public, private, protected, static, final
4. First element should be the data type
5. Second element should be the variable name. Trim trailing ; from variable name

Scan for methods

Methods generally follow the syntax:

[<access_modifier> ][<other_keywords> ]<return_data_type> <method_name>([<parameters>])[;|( {)]

e.g.

void getName()
protected Person getByName(String firstName, String lastName) throws Exception
public abstract void getAddress();
private final int getDays()
public static final Map<String, Object> setName(String name)

Extraction steps:

1. Replace string , with ,
2. Split string by consecutive spaces into a list
3. Remove keywords from list: public, private, protected, static, abstract
4. First element should be the return_data_type
5. Split second element by the first (
   1. First element should be the method_name
   2. Trim second element by trailing )
      1. Split remaining line by ,

Additional Notes:

• If the method is abstract, then the test method cannot be generated since the method cannot be invoked.

TestFileGenerator

1. Create test file
2. Generate code

Create test file

TODO

Generate code

1. Generate package code
2. Generate imports
3. Generate @RunWith(SpringJUnit4ClassRunner.class) annotation
4. Generate class
5. Generate member variables
6. Generate test methods

Generate Imports

1. Assert methods
2. Mockito methods and annotations

Generate Member Variables

1. Declare test class variable
2. If test class has member variables, then:
   • Declare member variables of test class and annotate with ‘@Mock’
   • Annotate test class variable with ‘@InjectMocks’
   • Implement ‘initMocks()’ method and annotate with ‘@Before’

Generate Test Methods

1. Scan for non-private methods and create a test method
   • e.g. found 'public void getName()', so generate 'public void getNameTest()' method in test file
   • Annotate test method with '@Test'