问为什么一些Flutter小部件测试在一起执行时会失败，但会单独通过？

EN

import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:rec/Components/Inputs/text_fields/DniTextField.dart';
import 'package:rec/Helpers/Validators.dart';

import '../../test_utils.dart';

void main() {
  testWidgets('DniTextField works with invalid DNI', (WidgetTester tester) async {
    var key = GlobalKey<DniTextFieldState>();
    var formKey = GlobalKey<FormState>();
    var onChangedResult;

    var widget = Form(
      key: formKey,
      child: DniTextField(
        key: key,
        onChange: (String value) {
          onChangedResult = value;
        },
        validator: (s) => Validators.verifyIdentityDocument(s),
      ),
    );
    await tester.pumpWidget(
      TestUtils.wrapPublicRoute(widget),
    );
    await tester.pumpAndSettle();

    // Test that widget has at least rendered
    TestUtils.widgetExists(widget);

    // Enter text into field with
    var widgetFinder = find.byWidget(widget);
    await tester.tap(widgetFinder);
    await tester.showKeyboard(widgetFinder);
    await tester.enterText(widgetFinder, 'invaliddni');

    await tester.pumpAndSettle();

    expect(onChangedResult, 'invaliddni');

    expect(formKey.currentState.validate(), false);
  });

  testWidgets('DniTextField works with valid DNI', (WidgetTester tester) async {
    var key = GlobalKey<DniTextFieldState>();
    var formKey = GlobalKey<FormState>();
    var onChangedResult;

    var widget = Form(
      key: formKey,
      child: DniTextField(
        key: key,
        onChange: (String value) {
          onChangedResult = value;
        },
        validator: (s) => Validators.verifyIdentityDocument(s),
      ),
    );
    await tester.pumpWidget(
      TestUtils.wrapPublicRoute(widget),
    );
    await tester.pumpAndSettle();

    // Enter text into field
    var widgetFinder = find.byType(DniTextField);
    await tester.tap(widgetFinder);
    await tester.showKeyboard(widgetFinder);
    await tester.enterText(widgetFinder, '80008000k');

    await tester.pumpAndSettle();

    expect(onChangedResult, '80008000k');

    expect(formKey.currentState.validate(), true);
  });

  testWidgets('DniTextField works with valid DNI with trailing space', (WidgetTester tester) async {
    var key = GlobalKey<DniTextFieldState>();
    var formKey = GlobalKey<FormState>();
    var onChangedResult;

    var widget = Form(
      key: formKey,
      child: DniTextField(
        key: key,
        onChange: (String value) {
          onChangedResult = value;
        },
        validator: (s) => Validators.verifyIdentityDocument(s),
      ),
    );
    await tester.pumpWidget(TestUtils.wrapPublicRoute(widget));
    await tester.pumpAndSettle();

    // Enter text into field
    var widgetFinder = find.byWidget(widget);
    await tester.tap(widgetFinder);
    await tester.showKeyboard(widgetFinder);
    await tester.enterText(widgetFinder, '80008000k ');

    await tester.pumpAndSettle();

    // The value emitted by the field, should be free of trailing whitespace
    expect(onChangedResult, '80008000k');

    expect(formKey.currentState.validate(), true);
  });
}

$ flutter test test/Components/inputs/dni_text_field_test.dart

══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following assertion was thrown running a test:
The finder "zero widgets with the given widget
(DniTextField-[LabeledGlobalKey<DniTextFieldState>#0fb86]) (ignoring offstage widgets)" (used in a
call to "tap()") could not find any matching widgets.

When the exception was thrown, this was the stack:
#0      WidgetController._getElementPoint (package:flutter_test/src/controller.dart:902:7)
#1      WidgetController.getCenter (package:flutter_test/src/controller.dart:841:12)
#2      WidgetController.tap (package:flutter_test/src/controller.dart:273:18)
#3      main.<anonymous closure> (file:///[masked]/test/Components/inputs/dni_text_field_test.dart:99:18)
<asynchronous suspension>
<asynchronous suspension>
(elided one frame from package:stack_trace)