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// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
/**
* This library contains an Expect class with static methods that can be used
* for simple unit-tests.
*/
library expect;
import 'package:meta/meta.dart';
/**
* Expect is used for tests that do not want to make use of the
* Dart unit test library - for example, the core language tests.
* Third parties are discouraged from using this, and should use
* the expect() function in the unit test library instead for
* test assertions.
*/
class Expect {
/**
* Return a slice of a string.
*
* The slice will contain at least the substring from [start] to the lower of
* [end] and `start + length`.
* If the result is no more than `length - 10` characters long,
* context may be added by extending the range of the slice, by decreasing
* [start] and increasing [end], up to at most length characters.
* If the start or end of the slice are not matching the start or end of
* the string, ellipses are added before or after the slice.
* Characters other than printable ASCII are escaped.
*/
static String _truncateString(String string, int start, int end, int length) {
if (end - start > length) {
end = start + length;
} else if (end - start < length) {
int overflow = length - (end - start);
if (overflow > 10) overflow = 10;
// Add context.
start = start - ((overflow + 1) ~/ 2);
end = end + (overflow ~/ 2);
if (start < 0) start = 0;
if (end > string.length) end = string.length;
}
StringBuffer buf = new StringBuffer();
if (start > 0) buf.write("...");
_escapeSubstring(buf, string, 0, string.length);
if (end < string.length) buf.write("...");
return buf.toString();
}
/// Return the string with characters that are not printable ASCII characters
/// escaped as either "\xXX" codes or "\uXXXX" codes.
static String _escapeString(String string) {
StringBuffer buf = new StringBuffer();
_escapeSubstring(buf, string, 0, string.length);
return buf.toString();
}
static _escapeSubstring(StringBuffer buf, String string, int start, int end) {
const hexDigits = "0123456789ABCDEF";
for (int i = start; i < end; i++) {
int code = string.codeUnitAt(i);
if (0x20 <= code && code < 0x7F) {
if (code == 0x5C) {
buf.write(r"\\");
} else {
buf.writeCharCode(code);
}
} else if (code < 0x100) {
buf.write(r"\x");
buf.write(hexDigits[code >> 4]);
buf.write(hexDigits[code & 15]);
} else {
buf.write(r"\u{");
buf.write(code.toRadixString(16).toUpperCase());
buf.write(r"}");
}
}
}
/**
* Find the difference between two strings.
*
* This finds the first point where two strings differ, and returns
* a text describing the difference.
*
* For small strings (length less than 20) nothing is done, and "" is
* returned. Small strings can be compared visually, but for longer strings
* only a slice containing the first difference will be shown.
*/
static String _stringDifference(String expected, String actual) {
if (expected.length < 20 && actual.length < 20) return "";
for (int i = 0; i < expected.length && i < actual.length; i++) {
if (expected.codeUnitAt(i) != actual.codeUnitAt(i)) {
int start = i;
i++;
while (i < expected.length && i < actual.length) {
if (expected.codeUnitAt(i) == actual.codeUnitAt(i)) break;
i++;
}
int end = i;
var truncExpected = _truncateString(expected, start, end, 20);
var truncActual = _truncateString(actual, start, end, 20);
return "at index $start: Expected <$truncExpected>, "
"Found: <$truncActual>";
}
}
return "";
}
/**
* Checks whether the expected and actual values are equal (using `==`).
*/
static void equals(var expected, var actual, [String reason = ""]) {
if (expected == actual) return;
String msg = _getMessage(reason);
if (expected is String && actual is String) {
String stringDifference = _stringDifference(expected, actual);
if (stringDifference.isNotEmpty) {
_fail("Expect.equals($stringDifference$msg) fails.");
}
_fail("Expect.equals(expected: <${_escapeString(expected)}>"
", actual: <${_escapeString(actual)}>$msg) fails.");
}
_fail("Expect.equals(expected: <$expected>, actual: <$actual>$msg) fails.");
}
/**
* Checks whether the actual value is a bool and its value is true.
*/
static void isTrue(var actual, [String reason = ""]) {
if (_identical(actual, true)) return;
String msg = _getMessage(reason);
_fail("Expect.isTrue($actual$msg) fails.");
}
/**
* Checks whether the actual value is a bool and its value is false.
*/
static void isFalse(var actual, [String reason = ""]) {
if (_identical(actual, false)) return;
String msg = _getMessage(reason);
_fail("Expect.isFalse($actual$msg) fails.");
}
/**
* Checks whether [actual] is null.
*/
static void isNull(actual, [String reason = ""]) {
if (null == actual) return;
String msg = _getMessage(reason);
_fail("Expect.isNull(actual: <$actual>$msg) fails.");
}
/**
* Checks whether [actual] is not null.
*/
static void isNotNull(actual, [String reason = ""]) {
if (null != actual) return;
String msg = _getMessage(reason);
_fail("Expect.isNotNull(actual: <$actual>$msg) fails.");
}
/**
* Checks whether the expected and actual values are identical
* (using `identical`).
*/
static void identical(var expected, var actual, [String reason = ""]) {
if (_identical(expected, actual)) return;
String msg = _getMessage(reason);
if (expected is String && actual is String) {
String note =
(expected == actual) ? ' Strings equal but not identical.' : '';
_fail("Expect.identical(expected: <${_escapeString(expected)}>"
", actual: <${_escapeString(actual)}>$msg) "
"fails.$note");
}
_fail("Expect.identical(expected: <$expected>, actual: <$actual>$msg) "
"fails.");
}
/**
* Finds equivalence classes of objects (by index) wrt. identity.
*
* Returns a list of lists of identical object indices per object.
* That is, `objects[i]` is identical to objects with indices in
* `_findEquivalences(objects)[i]`.
*
* Uses `[]` for objects that are only identical to themselves.
*/
static List<List<int>> _findEquivalences(List<Object> objects) {
var equivalences = new List<List<int>>.generate(objects.length, (_) => []);
for (int i = 0; i < objects.length; i++) {
if (equivalences[i].isNotEmpty) continue;
var o = objects[i];
for (int j = i + 1; j < objects.length; j++) {
if (equivalences[j].isNotEmpty) continue;
if (_identical(o, objects[j])) {
if (equivalences[i].isEmpty) {
equivalences[i].add(i);
}
equivalences[j] = equivalences[i]..add(j);
}
}
}
return equivalences;
}
static void _writeEquivalences(
List<Object> objects, List<List<int>> equivalences, StringBuffer buffer) {
var separator = "";
for (int i = 0; i < objects.length; i++) {
buffer.write(separator);
separator = ",";
var equivalence = equivalences[i];
if (equivalence.isEmpty) {
buffer.write('_');
} else {
int first = equivalence[0];
buffer..write('#')..write(first);
if (first == i) {
buffer..write('=')..write(objects[i]);
}
}
}
}
static void allIdentical(List<Object> objects, [String reason = ""]) {
if (objects.length <= 1) return;
String msg = _getMessage(reason);
var equivalences = _findEquivalences(objects);
var first = equivalences[0];
if (first.isNotEmpty && first.length == objects.length) return;
var buffer = new StringBuffer("Expect.allIdentical([");
_writeEquivalences(objects, equivalences, buffer);
buffer..write("]")..write(msg)..write(")");
_fail(buffer.toString());
}
/**
* Checks whether the expected and actual values are *not* identical
* (using `identical`).
*/
static void notIdentical(var unexpected, var actual, [String reason = ""]) {
if (!_identical(unexpected, actual)) return;
String msg = _getMessage(reason);
_fail("Expect.notIdentical(expected and actual: <$actual>$msg) fails.");
}
/**
* Checks that no two [objects] are `identical`.
*/
static void allDistinct(List<Object> objects, [String reason = ""]) {
String msg = _getMessage(reason);
var equivalences = _findEquivalences(objects);
bool hasEquivalence = false;
for (int i = 0; i < equivalences.length; i++) {
if (equivalences[i].isNotEmpty) {
hasEquivalence = true;
break;
}
}
if (!hasEquivalence) return;
var buffer = new StringBuffer("Expect.allDistinct([");
_writeEquivalences(objects, equivalences, buffer);
buffer..write("]")..write(msg)..write(")");
_fail(buffer.toString());
}
// Unconditional failure.
@alwaysThrows
static void fail(String msg) {
_fail("Expect.fail('$msg')");
}
/**
* Failure if the difference between expected and actual is greater than the
* given tolerance. If no tolerance is given, tolerance is assumed to be the
* value 4 significant digits smaller than the value given for expected.
*/
static void approxEquals(num expected, num actual,
[num tolerance = -1, String reason = ""]) {
if (tolerance < 0) {
tolerance = (expected / 1e4).abs();
}
// Note: use !( <= ) rather than > so we fail on NaNs
if ((expected - actual).abs() <= tolerance) return;
String msg = _getMessage(reason);
_fail('Expect.approxEquals(expected:<$expected>, actual:<$actual>, '
'tolerance:<$tolerance>$msg) fails');
}
static void notEquals(unexpected, actual, [String reason = ""]) {
if (unexpected != actual) return;
String msg = _getMessage(reason);
_fail("Expect.notEquals(unexpected: <$unexpected>, actual:<$actual>$msg) "
"fails.");
}
/**
* Checks that all elements in [expected] and [actual] are equal `==`.
* This is different than the typical check for identity equality `identical`
* used by the standard list implementation. It should also produce nicer
* error messages than just calling `Expect.equals(expected, actual)`.
*/
static void listEquals(List expected, List actual, [String reason = ""]) {
String msg = _getMessage(reason);
int n = (expected.length < actual.length) ? expected.length : actual.length;
for (int i = 0; i < n; i++) {
if (expected[i] != actual[i]) {
_fail('Expect.listEquals(at index $i, '
'expected: <${expected[i]}>, actual: <${actual[i]}>$msg) fails');
}
}
// We check on length at the end in order to provide better error
// messages when an unexpected item is inserted in a list.
if (expected.length != actual.length) {
_fail('Expect.listEquals(list length, '
'expected: <${expected.length}>, actual: <${actual.length}>$msg) '
'fails: Next element <'
'${expected.length > n ? expected[n] : actual[n]}>');
}
}
/**
* Checks that all [expected] and [actual] have the same set of keys (using
* the semantics of [Map.containsKey] to determine what "same" means. For
* each key, checks that the values in both maps are equal using `==`.
*/
static void mapEquals(Map expected, Map actual, [String reason = ""]) {
String msg = _getMessage(reason);
// Make sure all of the values are present in both, and they match.
for (final key in expected.keys) {
if (!actual.containsKey(key)) {
_fail('Expect.mapEquals(missing expected key: <$key>$msg) fails');
}
Expect.equals(expected[key], actual[key]);
}
// Make sure the actual map doesn't have any extra keys.
for (final key in actual.keys) {
if (!expected.containsKey(key)) {
_fail('Expect.mapEquals(unexpected key: <$key>$msg) fails');
}
}
}
/**
* Specialized equality test for strings. When the strings don't match,
* this method shows where the mismatch starts and ends.
*/
static void stringEquals(String expected, String actual,
[String reason = ""]) {
if (expected == actual) return;
String msg = _getMessage(reason);
String defaultMessage =
'Expect.stringEquals(expected: <$expected>", <$actual>$msg) fails';
if ((expected == null) || (actual == null)) {
_fail('$defaultMessage');
}
// Scan from the left until we find the mismatch.
int left = 0;
int right = 0;
int eLen = expected.length;
int aLen = actual.length;
while (true) {
if (left == eLen || left == aLen || expected[left] != actual[left]) {
break;
}
left++;
}
// Scan from the right until we find the mismatch.
int eRem = eLen - left; // Remaining length ignoring left match.
int aRem = aLen - left;
while (true) {
if (right == eRem ||
right == aRem ||
expected[eLen - right - 1] != actual[aLen - right - 1]) {
break;
}
right++;
}
// First difference is at index `left`, last at `length - right - 1`
// Make useful difference message.
// Example:
// Diff (1209..1209/1246):
// ...,{"name":"[ ]FallThroug...
// ...,{"name":"[ IndexError","kind":"class"},{"name":" ]FallThroug...
// (colors would be great!)
// Make snippets of up to ten characters before and after differences.
String leftSnippet = expected.substring(left < 10 ? 0 : left - 10, left);
int rightSnippetLength = right < 10 ? right : 10;
String rightSnippet =
expected.substring(eLen - right, eLen - right + rightSnippetLength);
// Make snippets of the differences.
String eSnippet = expected.substring(left, eLen - right);
String aSnippet = actual.substring(left, aLen - right);
// If snippets are long, elide the middle.
if (eSnippet.length > 43) {
eSnippet = eSnippet.substring(0, 20) +
"..." +
eSnippet.substring(eSnippet.length - 20);
}
if (aSnippet.length > 43) {
aSnippet = aSnippet.substring(0, 20) +
"..." +
aSnippet.substring(aSnippet.length - 20);
}
// Add "..." before and after, unless the snippets reach the end.
String leftLead = "...";
String rightTail = "...";
if (left <= 10) leftLead = "";
if (right <= 10) rightTail = "";
String diff = '\nDiff ($left..${eLen - right}/${aLen - right}):\n'
'$leftLead$leftSnippet[ $eSnippet ]$rightSnippet$rightTail\n'
'$leftLead$leftSnippet[ $aSnippet ]$rightSnippet$rightTail';
_fail("$defaultMessage$diff");
}
/**
* Checks that every element of [expected] is also in [actual], and that
* every element of [actual] is also in [expected].
*/
static void setEquals(Iterable expected, Iterable actual,
[String reason = ""]) {
final missingSet = new Set.from(expected);
missingSet.removeAll(actual);
final extraSet = new Set.from(actual);
extraSet.removeAll(expected);
if (extraSet.isEmpty && missingSet.isEmpty) return;
String msg = _getMessage(reason);
StringBuffer sb = new StringBuffer("Expect.setEquals($msg) fails");
// Report any missing items.
if (!missingSet.isEmpty) {
sb.write('\nExpected collection does not contain: ');
}
for (final val in missingSet) {
sb.write('$val ');
}
// Report any extra items.
if (!extraSet.isEmpty) {
sb.write('\nExpected collection should not contain: ');
}
for (final val in extraSet) {
sb.write('$val ');
}
_fail(sb.toString());
}
/**
* Checks that [expected] is equivalent to [actual].
*
* If the objects are iterables or maps, recurses into them.
*/
static void deepEquals(Object expected, Object actual) {
// Early exit check for equality.
if (expected == actual) return;
if (expected is String && actual is String) {
stringEquals(expected, actual);
} else if (expected is Iterable && actual is Iterable) {
var expectedLength = expected.length;
var actualLength = actual.length;
var length =
expectedLength < actualLength ? expectedLength : actualLength;
for (var i = 0; i < length; i++) {
deepEquals(expected.elementAt(i), actual.elementAt(i));
}
// We check on length at the end in order to provide better error
// messages when an unexpected item is inserted in a list.
if (expectedLength != actualLength) {
var nextElement =
(expectedLength > length ? expected : actual).elementAt(length);
_fail('Expect.deepEquals(list length, '
'expected: <$expectedLength>, actual: <$actualLength>) '
'fails: Next element <$nextElement>');
}
} else if (expected is Map && actual is Map) {
// Make sure all of the values are present in both and match.
for (final key in expected.keys) {
if (!actual.containsKey(key)) {
_fail('Expect.deepEquals(missing expected key: <$key>) fails');
}
Expect.deepEquals(expected[key], actual[key]);
}
// Make sure the actual map doesn't have any extra keys.
for (final key in actual.keys) {
if (!expected.containsKey(key)) {
_fail('Expect.deepEquals(unexpected key: <$key>) fails');
}
}
} else {
_fail("Expect.deepEquals(expected: <$expected>, actual: <$actual>) "
"fails.");
}
}
static bool _defaultCheck([dynamic e]) => true;
/**
* Calls the function [f] and verifies that it throws a `T`.
* The optional [check] function can provide additional validation
* that the correct object is being thrown. For example, to check
* the content of the thrown boject you could write this:
*
* Expect.throws<MyException>(myThrowingFunction,
* (e) => e.myMessage.contains("WARNING"));
*
* The type variable can be omitted and the type checked in [check]
* instead. This was traditionally done before Dart had generic methods.
*
* If `f` fails an expectation (i.e., throws an [ExpectException]), that
* exception is not caught by [Expect.throws]. The test is still considered
* failing.
*/
static void throws<T>(void f(),
[bool check(T error) = _defaultCheck, String reason = ""]) {
// TODO(vsm): Make check and reason nullable or change call sites.
// Existing tests pass null to set a reason and/or pass them through
// via helpers.
check ??= _defaultCheck;
reason ??= "";
String msg = reason.isEmpty ? "" : "($reason)";
if (f is! Function()) {
// Only throws from executing the function body should count as throwing.
// The failure to even call `f` should throw outside the try/catch.
_fail("Expect.throws$msg: Function f not callable with zero arguments");
}
try {
f();
} on Object catch (e, s) {
// A test failure doesn't count as throwing.
if (e is ExpectException) rethrow;
if (e is T && check(e as dynamic)) return;
// Throws something unexpected.
String type = "";
if (T != dynamic && T != Object) {
type = "<$T>";
}
_fail("Expect.throws$type$msg: "
"Unexpected '${Error.safeToString(e)}'\n$s");
}
_fail('Expect.throws$msg fails: Did not throw');
}
static void throwsArgumentError(void f(), [String reason = "ArgumentError"]) {
Expect.throws(f, (error) => error is ArgumentError, reason);
}
static void throwsAssertionError(void f(),
[String reason = "AssertionError"]) {
Expect.throws(f, (error) => error is AssertionError, reason);
}
static void throwsCastError(void f(), [String reason = "CastError"]) {
Expect.throws(f, (error) => error is CastError, reason);
}
static void throwsFormatException(void f(),
[String reason = "FormatException"]) {
Expect.throws(f, (error) => error is FormatException, reason);
}
static void throwsNoSuchMethodError(void f(),
[String reason = "NoSuchMethodError"]) {
Expect.throws(f, (error) => error is NoSuchMethodError, reason);
}
static void throwsRangeError(void f(), [String reason = "RangeError"]) {
Expect.throws(f, (error) => error is RangeError, reason);
}
static void throwsStateError(void f(), [String reason = "StateError"]) {
Expect.throws(f, (error) => error is StateError, reason);
}
static void throwsTypeError(void f(), [String reason = "TypeError"]) {
Expect.throws(f, (error) => error is TypeError, reason);
}
static void throwsUnsupportedError(void f(),
[String reason = "UnsupportedError"]) {
Expect.throws(f, (error) => error is UnsupportedError, reason);
}
/// Reports that there is an error in the test itself and not the code under
/// test.
///
/// It may be using the expect API incorrectly or failing some other
/// invariant that the test expects to be true.
static void testError(String message) {
_fail("Test error: $message");
}
/// Checks that [object] has type [T].
static void type<T>(dynamic object, [String reason = ""]) {
if (object is T) return;
String msg = _getMessage(reason);
_fail("Expect.type($object is $T$msg) fails "
"on ${Error.safeToString(object)}");
}
/// Checks that [object] does not have type [T].
static void notType<T>(dynamic object, [String reason = ""]) {
if (object is! T) return;
String msg = _getMessage(reason);
_fail("Expect.type($object is! $T$msg) fails"
"on ${Error.safeToString(object)}");
}
/// Checks that `Sub` is a subtype of `Super` at compile time and run time.
static bool subtype<Sub extends Super, Super>() {
List<Super> list = <Sub>[];
_subtypeAtRuntime<Sub, Super>();
}
/// Checks that `Sub` is a subtype of `Super` at run time.
///
/// This is similar to [subtype] but without the `Sub extends Super` generic
/// constraint, so a compiler is less likely to optimize away the `is` check
/// because the types appear to be unrelated.
static bool _subtypeAtRuntime<Sub, Super>() {
if (<Sub>[] is! List<Super>) {
fail("$Sub is not a subtype of $Super");
}
}
/// Checks that `Sub` is not a subtype of `Super` at run time.
static bool notSubtype<Sub, Super>() {
if (<Sub>[] is List<Super>) {
fail("$Sub is a subtype of $Super");
}
}
static String _getMessage(String reason) =>
(reason.isEmpty) ? "" : ", '$reason'";
@alwaysThrows
static void _fail(String message) {
throw new ExpectException(message);
}
}
/// Used in [Expect] because [Expect.identical] shadows the real [identical].
bool _identical(a, b) => identical(a, b);
/// Exception thrown on a failed expectation check.
///
/// Always recognized by [Expect.throws] as an unexpected error.
class ExpectException {
final String message;
ExpectException(this.message);
String toString() => message;
}
/// Is true iff type assertions are enabled.
// TODO(rnystrom): Remove this once all tests are no longer using it.
final bool typeAssertionsEnabled = (() {
try {
dynamic i = 42;
String s = i;
} on TypeError {
return true;
}
return false;
})();
/// Is true iff `assert` statements are enabled.
final bool assertStatementsEnabled = (() {
bool result = false;
assert(result = true);
return result;
})();
/// Is true iff checked mode is enabled.
// TODO(rnystrom): Remove this once all tests are no longer using it.
final bool checkedModeEnabled =
typeAssertionsEnabled && assertStatementsEnabled;