Instructions for Int Int Return Int Testing Template
Overview
These instructions will help you implement a code magnet microlab where the method is passed two integer parameters and returns an integer value. There are two steps in this process:
1. Implement the desired method and testing program outside of WAGS (Web Automated Grading System) and
2. Implement the code magnet lab in WAGS.
This is illustrated with the nCr method that returns the number of ways r items can be selected from n objects (i.e., combinations). You will change the nCr method to a method of your choice that has the same footprint:
input two integer parameters and returns an integer value.
The zip file IntIntReturnInt.zip contains four Java files:
1. IntIntReturnIntTest.java – this is heart of the test program and should not require any modification by the developer (or in this case the workshop participant). This will be uploaded as the test file when using the magnet creation page in WAGS.
2. ParamDataAndInvocations.java – the parameter values are
specified as two integer arrays in this file. Two methods are used to invoke a correct version of the method and the student version of the method. This file will be modified as described in the steps outlined below and uploaded as a helper file when using the magnet creation page in WAGS.
3. CorrectMethod.java – this file contains a correct version of the method being implemented as a code magnet method; it will be used to generate a correct return value for comparison with the method created in the code magnet lab by the student. This file will be modified as described in the steps outlined below and uploaded as a helper file when using the
magnet creation page in WAGS.
4. Student.java – this file contains the method to be developed as a code magnet microlab; it is only used to test the testing environment
independently of the WAGS system. DO NOT upload this file when you are using code magnet creation in WAGS.
Step 1
To complete step one you need to do the following:
Design your java method that has two integer parameters and returns an integer; put a copy inside of CorrectMethod.java and Student.java
Change the integer parameter values in
ParamDataAndInvocations.java to match the desired test values for your method. You can include as many values as you wish; be sure to include limiting cases for the method you are developing. For example in the choose method, there could be selecting zero items from a set of size zero.
Change invokeCorrectMethod and invokeStudentMethod to call the appropriate method in the CorrectMethod and Student classes, respectively.
Use your favorite IDE to test this testing framework.
Upload the four files (IntIntReturnIntTest.java,
ParamDataAndInvocations.java, CorrectMethod.java, Student.java) into the IDE
Set the first main method parameter value to any integer value of your choice; this is a nonce value that will be printed after testing is completed
Run the test program IntIntReturnIntTest.java and insure you get the expected results
Step 2
To create a code magnet lab you need to put the desired method the students will construct into “standard form” and then add alternative
magnets as appropriate. This is illustrated using the nCr method included in the download files.
“Standard form” means changing the desired method in the following ways:
All control statements, such as if, else, while, for are required to have a body enclosed in braces, even if the body is a single statement.
Put every declaration/initialization/statement on a separate line.
Incorrect Correct
if (n > 0) n--; if (n > 0){
n--;
}
a = 1; b = 2; a = 1;
b = 2;
Put the header of every control statement on a separate line ending in an opening brace; put every statement in the body on a separate line; put the closing brace on a separate line. NOTE: our parser does not currently handle switch statements, so please use if statements.
Most of these are the standard for Eclipse auto-formatting
NOT in standard form CORRECT standard form
int nCr(int n, int r) { if(n < r) return -1;
if (r == 0 || r == n) return 1;
return nCr(n-1, r-1) + nCr(n-1, r);
}
int nCr(int n, int r) { if(n < r) {
return -1;
}
if (r == 0 || r == n) { return 1;
}
return nCr(n-1, r-1) + nCr(n-1, r);
Then add a heading block that contains the title of the lab and a description for students who will use the lab. The format of this block is:
The first line in the file opening starting a comment line with /*
The title of the lab on a new line; this must be unique from other labs
A blank line
A description for students who will be using the lab to help their understand of the goal to be completed; this is usually multiple lines
A closing comment line ending with */
Comment block in processString.txt
/***********************************
Count Digit Characters
Return the number of digit characters, '0' through '9', in the given string parameter.
***********************************/
STEP 2A
Create a code magnet lab where all magnets are used to construct a correct solution.
Put the desired method into standard form, including the header block, do not put inside an enclosing class; name the file appropriately; we used nCr.java for the example provided.
Log onto the WAGS system using your account; in the top toolbar select Magnet Creation from the Admin pull down menu.
Go to the bottom right side of the screen and select Choose File under the
parse file option; navigate to the java file in standard form and select it.
Press the parse button once the file is selected; the text boxes on the right side of the screen should be filled in.
Go to choose file for the Testing class and upload the file IntIntReturnIntTest.java
Go to choose file for the Helper class and upload the file CorrectMethod.java
Add another helper class and upload ParamDataAndInvocations.java
Press create and test your code magnet lab to ensure it works correctly.
STEP 2B
It is often desirable to add alternative magnets so that students must choose between two similar magnets, such as one containing a >
comparison and the other containing a >= comparison. The file with the magnet lab in standard form can be modified inthe following way: duplicate the line that will become the alternative magnet then modify one of the two lines with the desired change. Here is the iterative nCr method where the alternative magnets are shown in red.
int nCr(int n, int r) { if(n < r) {
return 1;
return -1;
}
if (r = 0 || r = n) { if (r == 0 || r == n) { return 1;
}
return nCr(n, r-1) + nCr(n, r+1);
return nCr(n-1, r-1) + nCr(n-1, r);
return nCr(n-1, r) + nCr(n-1, r+1);
}
Add some alternative magnets to your method in standard form and then parse the new file in the magnet creation page. You should not need to change the test program or the helper files. Test your new lab and make changes as appropriate.
