Teffer (TEst diFFER) is a python-based tool used for automated testing. The tool runs an input program against a set of text-based tests. For each test, teffer generates a diff. All of the diffs are combined and inserted into an html output, which can be viewed in your browser of choice.

Teffer test-cases are made by creating a single directory full of subdirectories. Each subdirectory represents a single teffer test case. Each individual test directory should contain the following files:

• run.sh : A bash script which will be executed by teffer, with the current working directors as the execution directory. Within run.sh, the test-writer may use the token BASE_DIR, and teffer will replace this with the directory specified to the -s option of teffer (the directory with the code file to be tested). The test-writer can also use the TEST_DIR directory, which teffer will replace with the directory of the test case.
• expected.txt : A text file containing the expected output of this particular execution of your program.

Each test directory should also contain any necessary resource files needed for the test, such as input files.

A top-level test directory will have a structure that looks similar to this:

$ tree tests/
tests/
├── some-test
│   ├── resource-1.txt
|   ├── resource-2.txt
│   ├── run.sh
│   └── expected.txt
├── another-test
│   ├── resource-X.txt
│   ├── run.sh
│   └── expected.txt
└── cool-test
    ├── run.sh
    ├── options.txt
    └── expected.txt

Teffer will generate an actual.txt alongside each expected.txt after being executed. The actual.txt is the captured stdout from running the command in run.sh. Teffer will diff actual.txt and expected.txt. Teffer will generate an HTML file containing all of the diffs from the test run. This HTML file can be viewed in a web-browser. The options.txt file can contain key=value pairs, one per line, for extra settings to include in the output.

See the teffer/tests directory for a few example test cases.

See teffer.sh -h for details of command-line options.

Teffer has a default test suite, located in the ./tests. Since teffer itself is a testing framework, we use teffer to test itself. To run the teffer tests, just execute:

python3 teffer.py -t ./tests -s . -m test -o /tmp

Below is a step-by-step guide to running teffer on some test cases. The test-cases used are from a programming assignment given in CS 110 at the UofA.

Use or create a set of test cases to run teffer on. Show below is a screenshot of the contents of a tests directory.

The test directory contains many tests, each with a run.sh and an expected.txt file. Below are the contents of these two files in the bat-5 directory:

sed -i '' -e 's/^BAT_WIDTH.*/BAT_WIDTH = 5/g' BASE_DIR/bat.py
python3 BASE_DIR/bat.py

\****\_____      /\_/\      _____/****/
 \    *****\_____|* *|_____/*****    / 
  \         *****| - |*****         /  
   \_______ *****||*||***** _______/   
                 {   }

The student-submission directory contains a script named bat.py. I'm not going to show the contents here, so the solution isn't blown :).

The easiest way to run deffer is in the shell. Open up terminal and navigate to the desktop. From there, you'll need to run teffer.py with a few command-line arguments, like so:

Using the command-line arguments, teffer was told what directory the test-cases were in, what directory the solution was in, and the name of the diff file to generate.

After the run, you can double-click the studentdiff.html file to open it up in your browser. From here, you'll be able to check how many test-cases the student passed.