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bigcheck.js
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bigcheck.js
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var bigcheck = (function () {
var exports = {};
function isInteger(n) {
return n === +n && n === (n|0);
}
// GENERATORS
function resize(size) {
return size; // TODO
}
function rebias(bias) {
return bias; // TODO
}
function Generator(grow, shrink) {
this.grow = grow; // size -> Shrinkable
this.shrink = shrink; // value, bias -> Shrinkable
}
var integer = new Generator(
function numberGrow(size) {
return Math.floor(size * ((Math.random() * 2) - 1));
},
function numberShrink(value, bias) {
if (Math.random() < bias) {
return 0;
} else {
return Math.floor(value * ((Math.random() * 2) - 1));
}
}
);
var number = new Generator(
function numberGrow(size) {
return size * ((Math.random() * 2) - 1);
},
function numberShrink(value, bias) {
if (isInteger(value)) {
return integer.shrink(value, bias);
} else if (Math.random() < bias) {
return Math.floor(value);
} else {
return value * ((Math.random() * 2) - 1);
}
});
function array(elem, length) {
return new Generator(
function arrayGrow(size) {
var len = length || Math.random() * size;
var value = [];
for (var i = 0; i < len; i++) {
value[i] = elem.grow(resize(size));
}
return value;
},
function arrayShrink(value, bias) {
if ((value.length === 0) || ((length === undefined) && (Math.random() < bias))) {
return [];
} else {
var newValue = value.slice();
var i = Math.floor(Math.random() * newValue.length);
if ((length === undefined) && (Math.random() < 0.5)) {
newValue.splice(i, 1);
} else {
newValue[i] = elem.shrink(newValue[i], rebias(bias));
}
return newValue;
}
});
}
function tuple(elems) {
return new Generator(
function tupleGrow(size) {
var len = elems.length;
var value = [];
for (var i = 0; i < len; i++) {
value[i] = elems[i].grow(resize(size));
}
return value;
},
function tupleShrink(value, bias) {
var newValue = value.slice();
var i = Math.floor(Math.random() * newValue.length);
newValue[i] = elems[i].shrink(newValue[i], rebias(bias));
return newValue;
});
}
function ordinal(min, max) {
return new Generator(
function ordinalGrow(size) {
return Math.floor(Math.random() * (max - min + 1)) + min;
},
function ordinalShrink(value, bias) {
if (Math.random() < bias) {
return min;
} else {
return Math.floor(Math.random() * (value - min + 1)) + min;
}
});
}
function map(elems, to, from) {
forall('check map', elems,
// FIXME get rid of underscore dependency
function(e) { return _.isEqual(from(to(e)), e); }).assert();
return new Generator(
function mapGrow(size) {
return to(elems.grow(size));
},
function mapShrink(value, bias) {
return to(elems.shrink(from(value), bias));
}
);
}
var value = integer; // TODO any valid eve value
function facts(numColumns) {
return array(array(value, numColumns));
}
// PROPERTIES
function Success(numTests, options, prop) {
this.numTests = numTests;
this.options = options;
this.prop = prop;
}
function Failure(size, numTests, numShrinks, shrunkInput, shrunkOutput, input, output, options, prop) {
exports.lastFailure = this;
this.size = size;
this.numTests = numTests;
this.numShrinks = numShrinks;
this.shrunkInput = shrunkInput;
this.shrunkOutput = shrunkOutput;
this.inputs = input;
this.output = output;
this.options = options;
this.prop = prop;
}
function ForAll(name, gen, fun) {
this.name = name;
this.gen = gen;
this.fun = fun;
}
function forall(name, gen, fun) {
return new ForAll(name, gen, fun);
}
function foralls() {
var gens = Array.prototype.slice.call(arguments);
var name = gens.shift();
var fun = gens.pop();
var gen = tuple(gens);
return new ForAll(name, gen, function (values) {return fun.apply(null, values)});
}
ForAll.prototype = {
check: function (options) {
console.info("Testing: " + this.name);
console.time(this.name);
options = options || {};
var numTests = 0;
var maxTests = options.maxTests || 100;
var maxSize = options.maxSize || maxTests;
var input;
var output;
while (true) {
var size = maxSize * (numTests / maxTests);
input = this.gen.grow(size);
try {
output = this.fun.call(null, input);
} catch (exception) {
output = exception;
}
if (output !== true) break;
numTests += 1;
if (numTests >= maxTests) {
console.timeEnd(this.name);
return new Success(numTests, options, this);
}
}
var numShrinks = 0;
var maxShrinks = options.maxShrinks || (2 * maxTests);
var bias = options.bias || 0.25; // TODO grow/shrink bias
var shrunkInput = input;
var shrunkOutput;
while (true) {
var tryInput = this.gen.shrink(shrunkInput, bias);
var tryOutput;
try {
tryOutput = this.fun.call(null, tryInput);
} catch (exception) {
tryOutput = exception;
}
if (tryOutput !== true) {
shrunkInput = tryInput;
shrunkOutput = tryOutput;
}
numShrinks += 1;
if (numShrinks >= maxShrinks) {
console.timeEnd(this.name);
return new Failure(size, numTests, numShrinks, shrunkInput, shrunkOutput, input, output, options, this);
}
}
},
assert: function(options) {
var result = this.check(options);
if (result instanceof Failure) {
if (result.output instanceof Error) result.output = result.output.toString(); // Errors don't JSONify nicely
throw new Error(JSON.stringify(result));
} else {
return result;
}
},
recheck: function(input) {
var input = input || exports.lastFailure.shrunkInput;
if (input) {
return this.fun.call(null, input);
} else {
return true;
}
}
};
var char = map(ordinal(32, 126),
function toChar(n) { return String.fromCharCode(n); },
function fromChar(c) { return c.charCodeAt(); });
var string = map(array(char),
function toString(a) { return a.join(""); },
function fromString(s) { return s.split(""); });
// TESTS
// foralls("sum", number, number,
// function (a, b) {
// return (a + b) >= a;
// }).assert();
// foralls("random tuple failure", array(tuple([number, number, number])),
// function(_) {
// return Math.random() < 0.999;
// }).check({maxTests: 10000, maxShrinks: 20000, bias: 0});
// foralls("random array failure", array(array(number)),
// function(_) {
// return Math.random() < 0.999;
// }).check({maxTests: 10000, maxShrinks: 20000, bias: 0});
// foralls("arrays are not strictly sorted", array(number, 9),
// function(nums) {
// for (var i = 0; i < nums.length - 1; i++) {
// if (nums[i] >= nums[i+1]) return true;
// }
// return false;
// }).check({maxTests: 10000000, maxShrinks: 20000000, bias: 0});
exports = {number: number, integer: integer, array: array, tuple: tuple, value: value, facts: facts, forall: forall, foralls: foralls, map: map, ordinal: ordinal, char: char, string: string};
if (typeof module !== 'undefined' && module.exports) { // node.js
module.exports = exports;
} else { // browser
this.bigcheck = exports;
}
return exports;
})();