06-EJS-Ch3-exercises.js

var assert = require('assert');

var ___ = undefined;

/*
 * To complete the exercise, replace underscores in the 
 * code below with appropriate values to make the tests 
 * pass.
 * 
 * See README.md for installing the test library and 
 * running the tests.
 */



/*

## Minimum

The previous chapter introduced the standard function Math.min 
that returns its smallest argument. We can do that ourselves 
now. Write a function min that takes two arguments and returns 
their minimum.
*/

// your code here

describe("The 'min' function", function(){
	it("will find the minimum of two numbers", function(){
		assert.strictEqual(min(0,10), 0);
		assert.strictEqual(min(0,-10), -10);
	});	
});

/*

## Recursion

We’ve seen that % (the remainder operator) can be used to test 
whether a number is even or odd by using % 2 to check whether 
it’s divisible by two. Here’s another way to define whether a 
positive whole number is even or odd:


	Zero is even.

	One is odd.

	For any other number N, its evenness is the same as N - 2.

Define a recursive function isEven corresponding to this 
description. The function should accept a number parameter and 
return a Boolean.

Test it on 50 and 75. See how it behaves on -1. Why? Can you 
think of a way to fix this?

*/

// your code here

describe("The 'isEven' function", function(){
	it("can figure out even numbers", function(){
		assert.strictEqual(isEven(50), true);
	});
	it("can figure out odd numbers", function(){
		assert.strictEqual(isEven(75), false);
	});
	it("can handle negative numbers",function(){
		assert.strictEqual(isEven(-1), false);
		assert.strictEqual(isEven(-4), true);
	});
});

/*
Bean counting

You can get the Nth character, or letter, from a string by 
writing "string".charAt(N), similar to how you get its length 
with "s".length. The returned value will be a string containing 
only one character (for example, "b"). The first character has 
position zero, which causes the last one to be found at position 
string.length - 1. In other words, a two-character string has 
length 2, and its characters have positions 0 and 1.

Write a function countBs that takes a string as its only argument 
and returns a number that indicates how many uppercase “B” 
characters are in the string.

Next, write a function called countChar that behaves like countBs, 
except it takes a second argument that indicates the character 
that is to be counted (rather than counting only uppercase “B” 
characters). Rewrite countBs to make use of this new function.

*/  

// your code here

describe("The 'countBs' function", function(){
	it("correctly counts Bs",function(){
		assert.strictEqual(countBs("BBC"), 2);
	});
})

describe("The 'countChar' function", function(){
	it("correctly counts ks",function(){
		assert.strictEqual(countChar("kakkerlak", "k"), 4);
	});
})