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Take callbacks for actual and which
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This aligns these arguments with all the other failure formatting
arguments like `clause` and `label`. There may be some performance
benefit in some cases where a rejection from `softCheck` is ignored and
expensive String operations are avoid, but in the typical case this just
introduces closures which will be invoked shortly.

Replace the default empty list for `actual` with a default function.
This is a slight behavior change where passing `() => []` will not get
overwritten with the default, but passing `[]` would have. Only
defaulting for when the argument was not passed at all is slightly
better behavior.

Replace a bunch of `Iterable<String>` with `Iterable<String> Function()`
and invoke them at the moment the strings are needed.
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@natebosch
natebosch committed Feb 3, 2023
1 parent 8ab184b commit 1079df0
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Showing 11 changed files with 305 additions and 255 deletions.
28 changes: 16 additions & 12 deletions pkgs/checks/lib/src/checks.dart
View file
Original file line number Diff line number Diff line change
Expand Up @@ -65,12 +65,12 @@ Subject<T> check<T>(T value, {String? because}) => Subject._(_TestContext._root(
// TODO - switch between "a" and "an"
label: () => ['a $T'],
fail: (f) {
final which = f.rejection.which;
final which = f.rejection.which?.call();
throw TestFailure([
...prefixFirst('Expected: ', f.detail.expected),
...prefixFirst('Actual: ', f.detail.actual),
...indent(
prefixFirst('Actual: ', f.rejection.actual), f.detail.depth),
prefixFirst('Actual: ', f.rejection.actual()), f.detail.depth),
if (which != null && which.isNotEmpty)
...indent(prefixFirst('Which: ', which), f.detail.depth),
if (because != null) 'Reason: $because',
Expand Down Expand Up @@ -282,6 +282,8 @@ abstract class Context<T> {
FutureOr<Extracted<R>> Function(T) extract);
}

Iterable<String> _empty() => const [];

/// A property extracted from a value being checked, or a rejection.
class Extracted<T> {
final Rejection? rejection;
Expand All @@ -293,7 +295,8 @@ class Extracted<T> {
/// When a nesting is rejected with an omitted or empty [actual] argument, it
/// will be filled in with the [literal] representation of the value.
Extracted.rejection(
{Iterable<String> actual = const [], Iterable<String>? which})
{Iterable<String> Function() actual = _empty,
Iterable<String> Function()? which})
: rejection = Rejection(actual: actual, which: which),
value = null;
Extracted.value(T this.value) : rejection = null;
Expand All @@ -306,10 +309,11 @@ class Extracted<T> {
return Extracted.value(transform(value as T));
}

Extracted<T> _fillActual(Object? actual) => rejection == null ||
rejection!.actual.isNotEmpty
? this
: Extracted.rejection(actual: literal(actual), which: rejection!.which);
Extracted<T> _fillActual(Object? actual) =>
rejection == null || rejection!.actual != _empty
? this
: Extracted.rejection(
actual: () => literal(actual), which: rejection!.which);
}

abstract class _Optional<T> {
Expand Down Expand Up @@ -682,7 +686,7 @@ class Rejection {
/// message. All lines in the message will be indented to the level of the
/// expectation in the description, and printed following the descriptions of
/// any expectations that have already passed.
final Iterable<String> actual;
final Iterable<String> Function() actual;

/// A description of the way that [actual] failed to meet the expectation.
///
Expand All @@ -696,13 +700,13 @@ class Rejection {
///
/// When provided, this is printed following a "Which: " label at the end of
/// the output for the failure message.
final Iterable<String>? which;
final Iterable<String> Function()? which;

Rejection _fillActual(Object? value) => actual.isNotEmpty
Rejection _fillActual(Object? value) => actual != _empty
? this
: Rejection(actual: literal(value), which: which);
: Rejection(actual: () => literal(value), which: which);

Rejection({this.actual = const [], this.which});
Rejection({this.actual = _empty, this.which});
}

class ConditionSubject<T> implements Subject<T>, Condition<T> {
Expand Down
49 changes: 26 additions & 23 deletions pkgs/checks/lib/src/collection_equality.dart
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,19 +26,20 @@ import 'package:checks/context.dart';
/// Collections may be nested to a maximum depth of 1000. Recursive collections
/// are not allowed.
/// {@endtemplate}
Iterable<String>? deepCollectionEquals(Object actual, Object expected) {
Iterable<String> Function()? deepCollectionEquals(
Object actual, Object expected) {
try {
return _deepCollectionEquals(actual, expected, 0);
} on _ExceededDepthError {
return ['exceeds the depth limit of $_maxDepth'];
return () => ['exceeds the depth limit of $_maxDepth'];
}
}

const _maxDepth = 1000;

class _ExceededDepthError extends Error {}

Iterable<String>? _deepCollectionEquals(
Iterable<String> Function()? _deepCollectionEquals(
Object actual, Object expected, int depth) {
assert(actual is Iterable || actual is Map);
assert(expected is Iterable || expected is Map);
Expand All @@ -50,7 +51,7 @@ Iterable<String>? _deepCollectionEquals(
final currentExpected = toCheck.expected;
final path = toCheck.path;
final currentDepth = toCheck.depth;
Iterable<String>? rejectionWhich;
Iterable<String> Function()? rejectionWhich;
if (currentExpected is Set) {
rejectionWhich = _findSetDifference(
currentActual, currentExpected, path, currentDepth);
Expand All @@ -67,10 +68,10 @@ Iterable<String>? _deepCollectionEquals(
return null;
}

List<String>? _findIterableDifference(Object? actual,
List<String> Function()? _findIterableDifference(Object? actual,
Iterable<Object?> expected, _Path path, Queue<_Search> queue, int depth) {
if (actual is! Iterable) {
return ['${path}is not an Iterable'];
return () => ['${path}is not an Iterable'];
}
var actualIterator = actual.iterator;
var expectedIterator = expected.iterator;
Expand All @@ -79,13 +80,13 @@ List<String>? _findIterableDifference(Object? actual,
var expectedNext = expectedIterator.moveNext();
if (!expectedNext && !actualNext) break;
if (!expectedNext) {
return [
return () => [
'${path}has more elements than expected',
'expected an iterable with $index element(s)'
];
}
if (!actualNext) {
return [
return () => [
'${path}has too few elements',
'expected an iterable with at least ${index + 1} element(s)'
];
Expand All @@ -99,19 +100,19 @@ List<String>? _findIterableDifference(Object? actual,
} else if (expectedValue is Condition) {
final failure = softCheck(actualValue, expectedValue);
if (failure != null) {
final which = failure.rejection.which;
return [
final which = failure.rejection.which?.call();
return () => [
'has an element ${path.append(index)}that:',
...indent(failure.detail.actual.skip(1)),
...indent(prefixFirst('Actual: ', failure.rejection.actual),
...indent(prefixFirst('Actual: ', failure.rejection.actual()),
failure.detail.depth + 1),
if (which != null)
...indent(prefixFirst('which ', which), failure.detail.depth + 1)
];
}
} else {
if (actualValue != expectedValue) {
return [
return () => [
...prefixFirst('${path.append(index)}is ', literal(actualValue)),
...prefixFirst('which does not equal ', literal(expectedValue))
];
Expand All @@ -134,30 +135,30 @@ bool _elementMatches(Object? actual, Object? expected, int depth) {
return expected == actual;
}

Iterable<String>? _findSetDifference(
Iterable<String> Function()? _findSetDifference(
Object? actual, Set<Object?> expected, _Path path, int depth) {
if (actual is! Set) {
return ['${path}is not a Set'];
return () => ['${path}is not a Set'];
}
return unorderedCompare(
actual,
expected,
(actual, expected) => _elementMatches(actual, expected, depth),
(expected, _, count) => [
(expected, _, count) => () => [
...prefixFirst('${path}has no element to match ', literal(expected)),
if (count > 1) 'or ${count - 1} other elements',
],
(actual, _, count) => [
(actual, _, count) => () => [
...prefixFirst('${path}has an unexpected element ', literal(actual)),
if (count > 1) 'and ${count - 1} other unexpected elements',
],
);
}

Iterable<String>? _findMapDifference(
Iterable<String> Function()? _findMapDifference(
Object? actual, Map<Object?, Object?> expected, _Path path, int depth) {
if (actual is! Map) {
return ['${path}is not a Map'];
return () => ['${path}is not a Map'];
}
Iterable<String> describeEntry(MapEntry<Object?, Object?> entry) {
final key = literal(entry.key);
Expand All @@ -175,12 +176,12 @@ Iterable<String>? _findMapDifference(
(actual, expected) =>
_elementMatches(actual.key, expected.key, depth) &&
_elementMatches(actual.value, expected.value, depth),
(expectedEntry, _, count) => [
(expectedEntry, _, count) => () => [
...prefixFirst(
'${path}has no entry to match ', describeEntry(expectedEntry)),
if (count > 1) 'or ${count - 1} other entries',
],
(actualEntry, _, count) => [
(actualEntry, _, count) => () => [
...prefixFirst(
'${path}has unexpected entry ', describeEntry(actualEntry)),
if (count > 1) 'and ${count - 1} other unexpected entries',
Expand Down Expand Up @@ -241,12 +242,14 @@ class _Search {
/// Runtime is at least `O(|actual||expected|)`, and for collections with many
/// elements which compare as equal the runtime can reach
/// `O((|actual| + |expected|)^2.5)`.
Iterable<String>? unorderedCompare<T, E>(
Iterable<String> Function()? unorderedCompare<T, E>(
Iterable<T> actual,
Iterable<E> expected,
bool Function(T, E) elementsEqual,
Iterable<String> Function(E, int index, int count) unmatchedExpected,
Iterable<String> Function(T, int index, int count) unmatchedActual) {
Iterable<String> Function() Function(E, int index, int count)
unmatchedExpected,
Iterable<String> Function() Function(T, int index, int count)
unmatchedActual) {
final indexedExpected = expected.toList();
final indexedActual = actual.toList();
final adjacency = <List<int>>[];
Expand Down
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