gecko-dev/testing/modules/Assert.jsm

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JavaScript

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
// http://wiki.commonjs.org/wiki/Unit_Testing/1.0
// When you see a javadoc comment that contains a number, it's a reference to a
// specific section of the CommonJS spec.
//
// Originally from narwhal.js (http://narwhaljs.org)
// Copyright (c) 2009 Thomas Robinson <280north.com>
// MIT license: http://opensource.org/licenses/MIT
"use strict";
this.EXPORTED_SYMBOLS = [
"Assert"
];
Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
Components.utils.import("resource://gre/modules/ObjectUtils.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Promise",
"resource://gre/modules/Promise.jsm");
/**
* 1. The assert module provides functions that throw AssertionError's when
* particular conditions are not met.
*
* To use the module you'll need to instantiate it first, which allows consumers
* to override certain behavior on the newly obtained instance. For examples,
* see the javadoc comments for the `report` member function.
*/
var Assert = this.Assert = function(reporterFunc) {
if (reporterFunc)
this.setReporter(reporterFunc);
};
function instanceOf(object, type) {
return Object.prototype.toString.call(object) == "[object " + type + "]";
}
function replacer(key, value) {
if (value === undefined) {
return "" + value;
}
if (typeof value === "number" && (isNaN(value) || !isFinite(value))) {
return value.toString();
}
if (typeof value === "function" || instanceOf(value, "RegExp")) {
return value.toString();
}
return value;
}
const kTruncateLength = 128;
function truncate(text, newLength = kTruncateLength) {
if (typeof text == "string") {
return text.length < newLength ? text : text.slice(0, newLength);
} else {
return text;
}
}
function getMessage(error, prefix = "") {
let actual, expected;
// Wrap calls to JSON.stringify in try...catch blocks, as they may throw. If
// so, fall back to toString().
try {
actual = JSON.stringify(error.actual, replacer);
} catch (ex) {
actual = Object.prototype.toString.call(error.actual);
}
try {
expected = JSON.stringify(error.expected, replacer);
} catch (ex) {
expected = Object.prototype.toString.call(error.expected);
}
let message = prefix;
if (error.operator) {
message += (prefix ? " - " : "") + truncate(actual) + " " + error.operator +
" " + truncate(expected);
}
return message;
}
/**
* 2. The AssertionError is defined in assert.
*
* Example:
* new assert.AssertionError({
* message: message,
* actual: actual,
* expected: expected,
* operator: operator
* });
*
* At present only the four keys mentioned above are used and
* understood by the spec. Implementations or sub modules can pass
* other keys to the AssertionError's constructor - they will be
* ignored.
*/
Assert.AssertionError = function(options) {
this.name = "AssertionError";
this.actual = options.actual;
this.expected = options.expected;
this.operator = options.operator;
this.message = getMessage(this, options.message);
// The part of the stack that comes from this module is not interesting.
let stack = Components.stack;
do {
stack = stack.asyncCaller || stack.caller;
} while(stack && stack.filename && stack.filename.includes("Assert.jsm"))
this.stack = stack;
};
// assert.AssertionError instanceof Error
Assert.AssertionError.prototype = Object.create(Error.prototype, {
constructor: {
value: Assert.AssertionError,
enumerable: false,
writable: true,
configurable: true
}
});
var proto = Assert.prototype;
proto._reporter = null;
/**
* Set a custom assertion report handler function. Arguments passed in to this
* function are:
* err (AssertionError|null) An error object when the assertion failed or null
* when it passed
* message (string) Message describing the assertion
* stack (stack) Stack trace of the assertion function
*
* Example:
* ```js
* Assert.setReporter(function customReporter(err, message, stack) {
* if (err) {
* do_report_result(false, err.message, err.stack);
* } else {
* do_report_result(true, message, stack);
* }
* });
* ```
*
* @param reporterFunc
* (function) Report handler function
*/
proto.setReporter = function(reporterFunc) {
this._reporter = reporterFunc;
};
/**
* 3. All of the following functions must throw an AssertionError when a
* corresponding condition is not met, with a message that may be undefined if
* not provided. All assertion methods provide both the actual and expected
* values to the assertion error for display purposes.
*
* This report method only throws errors on assertion failures, as per spec,
* but consumers of this module (think: xpcshell-test, mochitest) may want to
* override this default implementation.
*
* Example:
* ```js
* // The following will report an assertion failure.
* this.report(1 != 2, 1, 2, "testing JS number math!", "==");
* ```
*
* @param failed
* (boolean) Indicates if the assertion failed or not
* @param actual
* (mixed) The result of evaluating the assertion
* @param expected (optional)
* (mixed) Expected result from the test author
* @param message (optional)
* (string) Short explanation of the expected result
* @param operator (optional)
* (string) Operation qualifier used by the assertion method (ex: '==')
*/
proto.report = function(failed, actual, expected, message, operator) {
let err = new Assert.AssertionError({
message: message,
actual: actual,
expected: expected,
operator: operator
});
if (!this._reporter) {
// If no custom reporter is set, throw the error.
if (failed) {
throw err;
}
} else {
this._reporter(failed ? err : null, err.message, err.stack);
}
};
/**
* 4. Pure assertion tests whether a value is truthy, as determined by !!guard.
* assert.ok(guard, message_opt);
* This statement is equivalent to assert.equal(true, !!guard, message_opt);.
* To test strictly for the value true, use assert.strictEqual(true, guard,
* message_opt);.
*
* @param value
* (mixed) Test subject to be evaluated as truthy
* @param message (optional)
* (string) Short explanation of the expected result
*/
proto.ok = function(value, message) {
this.report(!value, value, true, message, "==");
};
/**
* 5. The equality assertion tests shallow, coercive equality with ==.
* assert.equal(actual, expected, message_opt);
*
* @param actual
* (mixed) Test subject to be evaluated as equivalent to `expected`
* @param expected
* (mixed) Test reference to evaluate against `actual`
* @param message (optional)
* (string) Short explanation of the expected result
*/
proto.equal = function equal(actual, expected, message) {
this.report(actual != expected, actual, expected, message, "==");
};
/**
* 6. The non-equality assertion tests for whether two objects are not equal
* with != assert.notEqual(actual, expected, message_opt);
*
* @param actual
* (mixed) Test subject to be evaluated as NOT equivalent to `expected`
* @param expected
* (mixed) Test reference to evaluate against `actual`
* @param message (optional)
* (string) Short explanation of the expected result
*/
proto.notEqual = function notEqual(actual, expected, message) {
this.report(actual == expected, actual, expected, message, "!=");
};
/**
* 7. The equivalence assertion tests a deep equality relation.
* assert.deepEqual(actual, expected, message_opt);
*
* We check using the most exact approximation of equality between two objects
* to keep the chance of false positives to a minimum.
* `JSON.stringify` is not designed to be used for this purpose; objects may
* have ambiguous `toJSON()` implementations that would influence the test.
*
* @param actual
* (mixed) Test subject to be evaluated as equivalent to `expected`, including nested properties
* @param expected
* (mixed) Test reference to evaluate against `actual`
* @param message (optional)
* (string) Short explanation of the expected result
*/
proto.deepEqual = function deepEqual(actual, expected, message) {
this.report(!ObjectUtils.deepEqual(actual, expected), actual, expected, message, "deepEqual");
};
/**
* 8. The non-equivalence assertion tests for any deep inequality.
* assert.notDeepEqual(actual, expected, message_opt);
*
* @param actual
* (mixed) Test subject to be evaluated as NOT equivalent to `expected`, including nested properties
* @param expected
* (mixed) Test reference to evaluate against `actual`
* @param message (optional)
* (string) Short explanation of the expected result
*/
proto.notDeepEqual = function notDeepEqual(actual, expected, message) {
this.report(ObjectUtils.deepEqual(actual, expected), actual, expected, message, "notDeepEqual");
};
/**
* 9. The strict equality assertion tests strict equality, as determined by ===.
* assert.strictEqual(actual, expected, message_opt);
*
* @param actual
* (mixed) Test subject to be evaluated as strictly equivalent to `expected`
* @param expected
* (mixed) Test reference to evaluate against `actual`
* @param message (optional)
* (string) Short explanation of the expected result
*/
proto.strictEqual = function strictEqual(actual, expected, message) {
this.report(actual !== expected, actual, expected, message, "===");
};
/**
* 10. The strict non-equality assertion tests for strict inequality, as
* determined by !==. assert.notStrictEqual(actual, expected, message_opt);
*
* @param actual
* (mixed) Test subject to be evaluated as NOT strictly equivalent to `expected`
* @param expected
* (mixed) Test reference to evaluate against `actual`
* @param message (optional)
* (string) Short explanation of the expected result
*/
proto.notStrictEqual = function notStrictEqual(actual, expected, message) {
this.report(actual === expected, actual, expected, message, "!==");
};
function expectedException(actual, expected) {
if (!actual || !expected) {
return false;
}
if (instanceOf(expected, "RegExp")) {
return expected.test(actual);
// We need to guard against the right hand parameter of "instanceof" lacking
// the "prototype" property, which is true of arrow functions in particular.
} else if (!(typeof expected === "function" && !expected.prototype) &&
actual instanceof expected) {
return true;
} else if (expected.call({}, actual) === true) {
return true;
}
return false;
}
/**
* 11. Expected to throw an error:
* assert.throws(block, Error_opt, message_opt);
*
* @param block
* (function) Function block to evaluate and catch eventual thrown errors
* @param expected (optional)
* (mixed) Test reference to evaluate against the thrown result from `block`
* @param message (optional)
* (string) Short explanation of the expected result
*/
proto.throws = function(block, expected, message) {
let actual;
if (typeof expected === "string") {
message = expected;
expected = null;
}
try {
block();
} catch (e) {
actual = e;
}
message = (expected && expected.name ? " (" + expected.name + ")." : ".") +
(message ? " " + message : ".");
if (!actual) {
this.report(true, actual, expected, "Missing expected exception" + message);
}
if ((actual && expected && !expectedException(actual, expected))) {
throw actual;
}
this.report(false, expected, expected, message);
};
/**
* A promise that is expected to reject:
* assert.rejects(promise, expected, message);
*
* @param promise
* (promise) A promise that is expected to reject
* @param expected (optional)
* (mixed) Test reference to evaluate against the rejection result
* @param message (optional)
* (string) Short explanation of the expected result
*/
proto.rejects = function(promise, expected, message) {
return new Promise((resolve, reject) => {
if (typeof expected === "string") {
message = expected;
expected = null;
}
return promise.then(
() => this.report(true, null, expected, "Missing expected exception " + message),
err => {
if (expected && !expectedException(err, expected)) {
reject(err);
return;
}
this.report(false, err, expected, message);
resolve();
}
).then(null, reject);
});
};
function compareNumbers(expression, lhs, rhs, message, operator) {
let lhsIsNumber = typeof lhs == "number";
let rhsIsNumber = typeof rhs == "number";
if (lhsIsNumber && rhsIsNumber) {
this.report(expression, lhs, rhs, message, operator);
return;
}
let errorMessage;
if (!lhsIsNumber && !rhsIsNumber) {
errorMessage = "Neither '" + lhs + "' nor '" + rhs + "' are numbers";
} else {
errorMessage = "'" + (lhsIsNumber ? rhs : lhs) + "' is not a number";
}
this.report(true, lhs, rhs, errorMessage);
}
/**
* The lhs must be greater than the rhs.
* assert.greater(lhs, rhs, message_opt);
*
* @param lhs
* (number) The left-hand side value
* @param rhs
* (number) The right-hand side value
* @param message (optional)
* (string) Short explanation of the comparison result
*/
proto.greater = function greater(lhs, rhs, message) {
compareNumbers.call(this, lhs <= rhs, lhs, rhs, message, ">");
};
/**
* The lhs must be greater than or equal to the rhs.
* assert.greaterOrEqual(lhs, rhs, message_opt);
*
* @param lhs
* (number) The left-hand side value
* @param rhs
* (number) The right-hand side value
* @param message (optional)
* (string) Short explanation of the comparison result
*/
proto.greaterOrEqual = function greaterOrEqual(lhs, rhs, message) {
compareNumbers.call(this, lhs < rhs, lhs, rhs, message, ">=");
};
/**
* The lhs must be less than the rhs.
* assert.less(lhs, rhs, message_opt);
*
* @param lhs
* (number) The left-hand side value
* @param rhs
* (number) The right-hand side value
* @param message (optional)
* (string) Short explanation of the comparison result
*/
proto.less = function less(lhs, rhs, message) {
compareNumbers.call(this, lhs >= rhs, lhs, rhs, message, "<");
};
/**
* The lhs must be less than or equal to the rhs.
* assert.lessOrEqual(lhs, rhs, message_opt);
*
* @param lhs
* (number) The left-hand side value
* @param rhs
* (number) The right-hand side value
* @param message (optional)
* (string) Short explanation of the comparison result
*/
proto.lessOrEqual = function lessOrEqual(lhs, rhs, message) {
compareNumbers.call(this, lhs > rhs, lhs, rhs, message, "<=");
};