Code is executed within a Dockerized Ubuntu 14.04 container.

brainf**k (known as simply BF in this codebase)

"bf" fast Brainf**k Interpreter

Care has been taken to follow the standard implementation guidelines as outlined by The Epistle to the Implementors whenever possible. Specifically:

• The newline \n and carriage return \r are treated like any other character by this interpreter in terms of both input and output; there is no special behavior configured in this case
• For the program input, when EOF is reached, note that a value of -1 is stored in the cell under the pointer, which is considered a standard implementation, albeit not the most popular one. Keep that in mind when writing your BF programs as programs that assume otherwise is likely to cause an infinite loop.
• Hacks are not enabled: # and ! are treated like any other non-command character.
• The memory tape has been configured to contain exactly 30000 8-bit cells as per the original implementation of Brainf**k by Urban Müller (and therefore is not unbounded) and does not exhibit toroidal behavior - an out-of-bounds memory pointer is reported as an error
• Cell wrapping (0 - 1 -> 255, 255 + 1 -> 0) is enabled as per the standard implementation

The JavaScript CW-2 custom testing framework is used for testing brainf**k code. To execute the BF code with the desired input, simply make a call to the runBF function which optionally accepts 1 argument - the program input as a string. For example, if you want the output of your CAT program with the input "Codewars", simply do runBF("Codewars") in which case the string "Codewars" is returned provided your CAT program is correct. If no input is required, simply call runBF without any arguments.

A basic example of testing a Hello World program:

Test.describe("Your BF Hello World Program", function () {
  Test.it("should return the string \"Hello World!\"", function () {
    Test.assertEquals(runBF(), "Hello World!");
  });
});

And a basic example of testing a program that multiplies two numbers together:

Test.describe("Your BF Multiply Program", function () {
  Test.it("should work for some fixed tests", function () {
    Test.assertEquals(runBF(String.fromCharCode(3, 5)), String.fromCharCode(15));
    Test.assertEquals(runBF(String.fromCharCode(9, 8)), "H"); // "H" has character code 72
    Test.assertEquals(runBF(" \n"), "@"); // Cell wrapping at work - (10 * 32) % 256 === 64
  });
  Test.it("should work for some random tests", function () {
    for (var i = 0; i < 100; i++) {
      var a = ~~(Math.random() * 128); // Random number from 0 to 127 (both inclusive)
      var b = ~~(Math.random() * 128);
      Test.assertEquals(runBF(String.fromCharCode(a, b)), String.fromCharCode((a * b) % 256)); // allowing for cell wrapping when product exceeds 255
    }
  });
});

NOTE: Although the JavaScript CW-2 Framework contains many different methods, only the following should be needed in most cases to test BF output:

1. Test.describe
2. Test.it
3. Test.assert(Not)Equals

Test.expect may also be used in special circumstances but it is recommended to avoid it unless absolutely necessary.