Testing

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Test code that installs the magic_devtools integrations, and reset every static they leave behind so one test cannot leak enrichers, watchers or tapir pointers into the next.

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A Test That Installs#

dart

import 'package:crumbs/crumbs.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:magic/magic.dart';
import 'package:magic_devtools/crumbs.dart';
import 'package:magic_devtools/tapir.dart';
import 'package:tapir/tapir.dart';

void main() {
  setUpAll(TestWidgetsFlutterBinding.ensureInitialized);

  setUp(() {
    MagicApp.reset();
    Magic.flush();
    MagicRouter.reset();
    CrumbsStore.resetForTesting();
  });

  tearDown(() {
    MagicTapirIntegration.resetForTesting();
    MagicCrumbsIntegration.resetForTesting();
  });

  test('installs the Magic enrichers once', () {
    MagicTapirIntegration.install();
    MagicTapirIntegration.install();

    expect(TapirPlugin.enrichers, hasLength(14));
  });
}

Every resetForTesting() and isInstalled here is @visibleForTesting: call them from tests only.

What Each Reset Clears#

Call	Clears	Leaves
`MagicDevtools.resetForTesting()`	Uninstalls the `ExceptionWatcher` and `DumpWatcher` that `installPre()` registered, which restores `FlutterError.onError`, the platform error callback and `debugPrint`; the next `installPre()` registers a new pair	The plugins and the perf integration
`MagicTapirIntegration.resetForTesting()`	Removes the 14 enrichers from `TapirPlugin.enrichers`, clears the navigate adapter, cancels the Echo subscription, drops the install guard	Enrichers the app added itself
`MagicCrumbsIntegration.resetForTesting()`	Drops the install guard; resets `pendingHttpCountReader`, `recentLogsReader` and `recentExceptionsReader` to zero and empty lists	The adapter and the five watchers registered with `CrumbsPlugin`, and their `EventDispatcher` listeners
`MagicPerfIntegration.resetForTesting()`	Drops the install guard, clears the session counters and route transitions, removes `MagicPerfHooks.sink` and the insight contributor, uninstalls the frame watcher, turns wind's counting off, restores the interaction sources and puts every tapir perf pointer back to the default tapir declared	The navigator observer, which `MagicRouter.reset()` drops with the router
`MagicPreview.resetForTesting()`	The registered entries	Routes already added; `MagicRouter.reset()` clears those

Pair them with the resets of the packages underneath:

Call	Why
`CrumbsStore.resetForTesting()`	Empties every crumbs buffer and restores the default masked names, including the auth header `MagicCrumbsIntegration.install()` added
`EventDispatcher.instance.clear()`	Removes the model, cache, event, gate and query listeners, since the watchers cannot remove their own
`MagicRouter.reset()`	A fresh router, unlocked, without the perf observer or the preview routes
`Gate.manager.flush()`	Empties the gate result cache the gate enrichers read

Faking Interactions#

tapir's PerfInteraction has a private constructor, so a host test cannot open a real interaction without a perf session over the VM Service. Three static fields on MagicPerfIntegration decide what counts as one, and a test may replace them:

Field	Default reads
`zoneInteraction`	A `PerfInteraction` stored in the zone under `PerfInteraction.zoneKey` (`#tapir_interaction`)
`interactionIdAt`	tapir's `perfInteractionAt(us)`
`activeInteractionId`	tapir's `activeInteraction()`

MagicPerfIntegration.resetForTesting() puts all three back.

Gotchas#

Mistake	Fix
Calling `MagicDevtools.installPre()` in a `testWidgets` case and restoring `debugPrint` in `tearDown`.	flutter_test checks its debug variables right after the test body, before `tearDown`; call `MagicDevtools.resetForTesting()` at the end of the body.
Resetting `MagicCrumbsIntegration` and expecting its watchers gone.	The reset drops the guard only; clear `EventDispatcher.instance` too, or a reinstall records each event twice.
Calling `MagicPerfIntegration.install()` twice across tests without `MagicRouter.reset()`.	The reset clears the observer flag, so the next install adds a second observer to the same router; reset the router as well.
Asserting crumbs HTTP records while using `Http.fake()`.	The fake driver ignores interceptors; assert on the fake.
Expecting `MagicCrumbsIntegration.resetForTesting()` to restore the masked header list.	It does not; `CrumbsStore.resetForTesting()` restores crumbs' defaults, and the next `install()` adds the auth header again.

Installation: what each install call wires.
Tapir Integration: the enrichers the reset removes.
Crumbs Integration: the watchers and the tapir bridge.
Performance: the perf pointers and the interaction links.

A Test That Installs#

What Each Reset Clears#

Faking Interactions#

Gotchas#

Related Documentation#