Suggested jasmine style

gistfile1.js

require('yourModule', function (sut) {

	var testValue, result;

	describe('given testValue is 1', function () {

		// ARRANGE
		beforeEach(function () {
			testValue = 1;
		});

		// ACT
		describe('when doIt is called', function () {

			beforeEach(function () {
				result = sut.doIt(testValue);
			});
			
			// ASSERT
			it('should return "foo"', function () {
				expect(result).toBe('foo');
			});
		});
		
		// ACT
		describe('when doTheOtherThing is called', function () {
			
			beforeEach(function() {
				result = sut.doTheOtherThing(testValue);
			});

			// ASSERT
			it('should return "bar"', function () {
				expect(result).toBe('bar');
			});
		});

		// ARRANGE
		describe('and given some other option', function () {
			var someOtherOption;
			beforeEach(function () {
				someOtherOption = true;
			});

			// ACT
			describe('when doTheLastThing', function () {
				
				beforeEach(function () {
					result = sut.doTheLastThing(testValue, someOtherOption);
				});
				
				// ASSERT
				it('result should be true', function () {
					expect(result).toBeTrue();
				});
			});
		})
	});
});