StreamMatcher class abstract

A matcher that matches events from Streams or StreamQueues.

Stream matchers are designed to make it straightforward to create complex expectations for streams, and to interleave expectations with the rest of a test. They can be used on a Stream to match all events it emits:

expect(stream, emitsInOrder([
  // Values match individual events.
  "Ready.",

  // Matchers also run against individual events.
  startsWith("Loading took"),

  // Stream matchers can be nested. This asserts that one of two events are
  // emitted after the "Loading took" line.
  emitsAnyOf(["Succeeded!", "Failed!"]),

  // By default, more events are allowed after the matcher finishes
  // matching. This asserts instead that the stream emits a done event and
  // nothing else.
  emitsDone
]));

It can also match a StreamQueue, in which case it consumes the matched events. The call to expect returns a Future that completes when the matcher is done matching. You can await this to consume different events at different times:

var stdout = StreamQueue(stdoutLineStream);

// Ignore lines from the process until it's about to emit the URL.
await expectLater(stdout, emitsThrough('WebSocket URL:'));

// Parse the next line as a URL.
var url = Uri.parse(await stdout.next);
expect(url.host, equals('localhost'));

// You can match against the same StreamQueue multiple times.
await expectLater(stdout, emits('Waiting for connection...'));

Users can call StreamMatcher to create custom matchers.

Inheritance

• Object
• Matcher
• StreamMatcher

Constructors

StreamMatcher(Future<String?> matchQueue(StreamQueue), String description)

Creates a new StreamMatcher described by description that matches events with matchQueue.

factory

Properties

description → String

The description of this matcher.

no setter

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

describe(Description description) → Description

Builds a textual description of the matcher.

inherited

describeMismatch(dynamic item, Description mismatchDescription, Map matchState, bool verbose) → Description

Builds a textual description of a specific mismatch.

inherited

matches(dynamic item, Map matchState) → bool

Does the matching of the actual vs expected values.

inherited

matchQueue(StreamQueue queue) → Future<String?>

Tries to match events emitted by queue.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited