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x/ramda/test/find.js

:ram: Practical functional Javascript
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var R = require('../source');var eq = require('./shared/eq');var listXf = require('./helpers/listXf');

describe('find', function() { var obj1 = {x: 100}; var obj2 = {x: 200}; var a = [11, 10, 9, 'cow', obj1, 8, 7, 100, 200, 300, obj2, 4, 3, 2, 1, 0]; var even = function(x) { return x % 2 === 0; }; var gt100 = function(x) { return x > 100; }; var isStr = function(x) { return typeof x === 'string'; }; var xGt100 = function(o) { return o && o.x > 100; }; var intoArray = R.into([]);
it('returns the first element that satisfies the predicate', function() { eq(R.find(even, a), 10); eq(R.find(gt100, a), 200); eq(R.find(isStr, a), 'cow'); eq(R.find(xGt100, a), obj2); });
it('transduces the first element that satisfies the predicate into an array', function() { eq(intoArray(R.find(even), a), [10]); eq(intoArray(R.find(gt100), a), [200]); eq(intoArray(R.find(isStr), a), ['cow']); eq(intoArray(R.find(xGt100), a), [obj2]); });
it('returns `undefined` when no element satisfies the predicate', function() { eq(R.find(even, ['zing']), undefined); });
it('returns `undefined` in array when no element satisfies the predicate into an array', function() { eq(intoArray(R.find(even), ['zing']), [undefined]); });
it('returns `undefined` when given an empty list', function() { eq(R.find(even, []), undefined); });
it('returns `undefined` into an array when given an empty list', function() { eq(intoArray(R.find(even), []), [undefined]); });
it('dispatches to transformer objects', function() { eq(R.find(R.identity, listXf), { f: R.identity, found: false, xf: listXf }); });});