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Side by Side Diff: mojo/dart/testing/expect.dart

Issue 1132063007: Rationalize Dart mojo and sky package structure (Closed) Base URL: https://github.com/domokit/mojo.git@master
Patch Set: Created 5 years, 7 months ago
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1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
2 // for details. All rights reserved. Use of this source code is governed by a
3 // BSD-style license that can be found in the LICENSE file.
4
5 /**
6 * This library contains an Expect class with static methods that can be used
7 * for simple unit-tests.
8 */
9 library expect;
10
11 /**
12 * Expect is used for tests that do not want to make use of the
13 * Dart unit test library - for example, the core language tests.
14 * Third parties are discouraged from using this, and should use
15 * the expect() function in the unit test library instead for
16 * test assertions.
17 */
18 class Expect {
19 /**
20 * Return a slice of a string.
21 *
22 * The slice will contain at least the substring from [start] to the lower of
23 * [end] and `start + length`.
24 * If the result is no more than `length - 10` characters long,
25 * context may be added by extending the range of the slice, by decreasing
26 * [start] and increasing [end], up to at most length characters.
27 * If the start or end of the slice are not matching the start or end of
28 * the string, ellipses are added before or after the slice.
29 * Control characters may be encoded as "\xhh" codes.
30 */
31 static String _truncateString(String string, int start, int end, int length) {
32 if (end - start > length) {
33 end = start + length;
34 } else if (end - start < length) {
35 int overflow = length - (end - start);
36 if (overflow > 10) overflow = 10;
37 // Add context.
38 start = start - ((overflow + 1) ~/ 2);
39 end = end + (overflow ~/ 2);
40 if (start < 0) start = 0;
41 if (end > string.length) end = string.length;
42 }
43 if (start == 0 && end == string.length) return string;
44 StringBuffer buf = new StringBuffer();
45 if (start > 0) buf.write("...");
46 for (int i = start; i < end; i++) {
47 int code = string.codeUnitAt(i);
48 if (code < 0x20) {
49 buf.write(r"\x");
50 buf.write("0123456789abcdef"[code ~/ 16]);
51 buf.write("0123456789abcdef"[code % 16]);
52 } else {
53 buf.writeCharCode(string.codeUnitAt(i));
54 }
55 }
56 if (end < string.length) buf.write("...");
57 return buf.toString();
58 }
59
60 /**
61 * Find the difference between two strings.
62 *
63 * This finds the first point where two strings differ, and returns
64 * a text describing the difference.
65 *
66 * For small strings (length less than 20) nothing is done, and null is
67 * returned. Small strings can be compared visually, but for longer strings
68 * only a slice containing the first difference will be shown.
69 */
70 static String _stringDifference(String expected, String actual) {
71 if (expected.length < 20 && actual.length < 20) return null;
72 for (int i = 0; i < expected.length && i < actual.length; i++) {
73 if (expected.codeUnitAt(i) != actual.codeUnitAt(i)) {
74 int start = i;
75 i++;
76 while (i < expected.length && i < actual.length) {
77 if (expected.codeUnitAt(i) == actual.codeUnitAt(i)) break;
78 i++;
79 }
80 int end = i;
81 var truncExpected = _truncateString(expected, start, end, 20);
82 var truncActual = _truncateString(actual, start, end, 20);
83 return "at index $start: Expected <$truncExpected>, "
84 "Found: <$truncActual>";
85 }
86 }
87 return null;
88 }
89
90 /**
91 * Checks whether the expected and actual values are equal (using `==`).
92 */
93 static void equals(var expected, var actual, [String reason = null]) {
94 if (expected == actual) return;
95 String msg = _getMessage(reason);
96 if (expected is String && actual is String) {
97 String stringDifference = _stringDifference(expected, actual);
98 if (stringDifference != null) {
99 _fail("Expect.equals($stringDifference$msg) fails.");
100 }
101 }
102 _fail("Expect.equals(expected: <$expected>, actual: <$actual>$msg) fails.");
103 }
104
105 /**
106 * Checks whether the actual value is a bool and its value is true.
107 */
108 static void isTrue(var actual, [String reason = null]) {
109 if (_identical(actual, true)) return;
110 String msg = _getMessage(reason);
111 _fail("Expect.isTrue($actual$msg) fails.");
112 }
113
114 /**
115 * Checks whether the actual value is a bool and its value is false.
116 */
117 static void isFalse(var actual, [String reason = null]) {
118 if (_identical(actual, false)) return;
119 String msg = _getMessage(reason);
120 _fail("Expect.isFalse($actual$msg) fails.");
121 }
122
123 /**
124 * Checks whether [actual] is null.
125 */
126 static void isNull(actual, [String reason = null]) {
127 if (null == actual) return;
128 String msg = _getMessage(reason);
129 _fail("Expect.isNull(actual: <$actual>$msg) fails.");
130 }
131
132 /**
133 * Checks whether [actual] is not null.
134 */
135 static void isNotNull(actual, [String reason = null]) {
136 if (null != actual) return;
137 String msg = _getMessage(reason);
138 _fail("Expect.isNotNull(actual: <$actual>$msg) fails.");
139 }
140
141 /**
142 * Checks whether the expected and actual values are identical
143 * (using `identical`).
144 */
145 static void identical(var expected, var actual, [String reason = null]) {
146 if (_identical(expected, actual)) return;
147 String msg = _getMessage(reason);
148 _fail("Expect.identical(expected: <$expected>, actual: <$actual>$msg) "
149 "fails.");
150 }
151
152 // Unconditional failure.
153 static void fail(String msg) {
154 _fail("Expect.fail('$msg')");
155 }
156
157 /**
158 * Failure if the difference between expected and actual is greater than the
159 * given tolerance. If no tolerance is given, tolerance is assumed to be the
160 * value 4 significant digits smaller than the value given for expected.
161 */
162 static void approxEquals(num expected,
163 num actual,
164 [num tolerance = null,
165 String reason = null]) {
166 if (tolerance == null) {
167 tolerance = (expected / 1e4).abs();
168 }
169 // Note: use !( <= ) rather than > so we fail on NaNs
170 if ((expected - actual).abs() <= tolerance) return;
171
172 String msg = _getMessage(reason);
173 _fail('Expect.approxEquals(expected:<$expected>, actual:<$actual>, '
174 'tolerance:<$tolerance>$msg) fails');
175 }
176
177 static void notEquals(unexpected, actual, [String reason = null]) {
178 if (unexpected != actual) return;
179 String msg = _getMessage(reason);
180 _fail("Expect.notEquals(unexpected: <$unexpected>, actual:<$actual>$msg) "
181 "fails.");
182 }
183
184 /**
185 * Checks that all elements in [expected] and [actual] are equal `==`.
186 * This is different than the typical check for identity equality `identical`
187 * used by the standard list implementation. It should also produce nicer
188 * error messages than just calling `Expect.equals(expected, actual)`.
189 */
190 static void listEquals(List expected, List actual, [String reason = null]) {
191 String msg = _getMessage(reason);
192 int n = (expected.length < actual.length) ? expected.length : actual.length;
193 for (int i = 0; i < n; i++) {
194 if (expected[i] != actual[i]) {
195 _fail('Expect.listEquals(at index $i, '
196 'expected: <${expected[i]}>, actual: <${actual[i]}>$msg) fails');
197 }
198 }
199 // We check on length at the end in order to provide better error
200 // messages when an unexpected item is inserted in a list.
201 if (expected.length != actual.length) {
202 _fail('Expect.listEquals(list length, '
203 'expected: <${expected.length}>, actual: <${actual.length}>$msg) '
204 'fails: Next element <'
205 '${expected.length > n ? expected[n] : actual[n]}>');
206 }
207 }
208
209 /**
210 * Checks that all [expected] and [actual] have the same set of keys (using
211 * the semantics of [Map.containsKey] to determine what "same" means. For
212 * each key, checks that the values in both maps are equal using `==`.
213 */
214 static void mapEquals(Map expected, Map actual, [String reason = null]) {
215 String msg = _getMessage(reason);
216
217 // Make sure all of the values are present in both and match.
218 for (final key in expected.keys) {
219 if (!actual.containsKey(key)) {
220 _fail('Expect.mapEquals(missing expected key: <$key>$msg) fails');
221 }
222
223 Expect.equals(expected[key], actual[key]);
224 }
225
226 // Make sure the actual map doesn't have any extra keys.
227 for (final key in actual.keys) {
228 if (!expected.containsKey(key)) {
229 _fail('Expect.mapEquals(unexpected key: <$key>$msg) fails');
230 }
231 }
232 }
233
234 /**
235 * Specialized equality test for strings. When the strings don't match,
236 * this method shows where the mismatch starts and ends.
237 */
238 static void stringEquals(String expected,
239 String actual,
240 [String reason = null]) {
241 String msg = _getMessage(reason);
242 String defaultMessage =
243 'Expect.stringEquals(expected: <$expected>", <$actual>$msg) fails';
244
245 if (expected == actual) return;
246 if ((expected == null) || (actual == null)) {
247 _fail('$defaultMessage');
248 }
249 // scan from the left until we find a mismatch
250 int left = 0;
251 int eLen = expected.length;
252 int aLen = actual.length;
253 while (true) {
254 if (left == eLen) {
255 assert (left < aLen);
256 String snippet = actual.substring(left, aLen);
257 _fail('$defaultMessage\nDiff:\n...[ ]\n...[ $snippet ]');
258 return;
259 }
260 if (left == aLen) {
261 assert (left < eLen);
262 String snippet = expected.substring(left, eLen);
263 _fail('$defaultMessage\nDiff:\n...[ ]\n...[ $snippet ]');
264 return;
265 }
266 if (expected[left] != actual[left]) {
267 break;
268 }
269 left++;
270 }
271
272 // scan from the right until we find a mismatch
273 int right = 0;
274 while (true) {
275 if (right == eLen) {
276 assert (right < aLen);
277 String snippet = actual.substring(0, aLen - right);
278 _fail('$defaultMessage\nDiff:\n[ ]...\n[ $snippet ]...');
279 return;
280 }
281 if (right == aLen) {
282 assert (right < eLen);
283 String snippet = expected.substring(0, eLen - right);
284 _fail('$defaultMessage\nDiff:\n[ ]...\n[ $snippet ]...');
285 return;
286 }
287 // stop scanning if we've reached the end of the left-to-right match
288 if (eLen - right <= left || aLen - right <= left) {
289 break;
290 }
291 if (expected[eLen - right - 1] != actual[aLen - right - 1]) {
292 break;
293 }
294 right++;
295 }
296 String eSnippet = expected.substring(left, eLen - right);
297 String aSnippet = actual.substring(left, aLen - right);
298 String diff = '\nDiff:\n...[ $eSnippet ]...\n...[ $aSnippet ]...';
299 _fail('$defaultMessage$diff');
300 }
301
302 /**
303 * Checks that every element of [expected] is also in [actual], and that
304 * every element of [actual] is also in [expected].
305 */
306 static void setEquals(Iterable expected,
307 Iterable actual,
308 [String reason = null]) {
309 final missingSet = new Set.from(expected);
310 missingSet.removeAll(actual);
311 final extraSet = new Set.from(actual);
312 extraSet.removeAll(expected);
313
314 if (extraSet.isEmpty && missingSet.isEmpty) return;
315 String msg = _getMessage(reason);
316
317 StringBuffer sb = new StringBuffer("Expect.setEquals($msg) fails");
318 // Report any missing items.
319 if (!missingSet.isEmpty) {
320 sb.write('\nExpected collection does not contain: ');
321 }
322
323 for (final val in missingSet) {
324 sb.write('$val ');
325 }
326
327 // Report any extra items.
328 if (!extraSet.isEmpty) {
329 sb.write('\nExpected collection should not contain: ');
330 }
331
332 for (final val in extraSet) {
333 sb.write('$val ');
334 }
335 _fail(sb.toString());
336 }
337
338 /**
339 * Calls the function [f] and verifies that it throws an exception.
340 * The optional [check] function can provide additional validation
341 * that the correct exception is being thrown. For example, to check
342 * the type of the exception you could write this:
343 *
344 * Expect.throws(myThrowingFunction, (e) => e is MyException);
345 */
346 static void throws(void f(),
347 [_CheckExceptionFn check = null,
348 String reason = null]) {
349 try {
350 f();
351 } catch (e, s) {
352 if (check != null) {
353 if (!check(e)) {
354 String msg = reason == null ? "" : reason;
355 _fail("Expect.throws($msg): Unexpected '$e'\n$s");
356 }
357 }
358 return;
359 }
360 String msg = reason == null ? "" : reason;
361 _fail('Expect.throws($msg) fails');
362 }
363
364 static String _getMessage(String reason)
365 => (reason == null) ? "" : ", '$reason'";
366
367 static void _fail(String message) {
368 throw new ExpectException(message);
369 }
370 }
371
372 bool _identical(a, b) => identical(a, b);
373
374 typedef bool _CheckExceptionFn(exception);
375
376 class ExpectException implements Exception {
377 ExpectException(this.message);
378 String toString() => message;
379 String message;
380 }
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