bug(Stepper): Stepper `reset()` Method Marks Form Controls as `Touched/Dirty`, Triggering Validation Errors

[naithagoni]

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

The reset() method of Angular Material's mat-stepper component is expected to reset the stepper and associated form groups to their initial state, clearing any user input and resetting form validation states. However, when using the reset() method with reactive forms, the form controls are unexpectedly marked as touched or dirty, causing validation errors to display immediately. This behavior is not intuitive and negatively impacts user experience, as the form appears to have errors even though no user interaction has occurred post-reset.

Reproduction

StackBlitz link:
Steps to reproduce:

1. Create a stepper with multiple steps using Angular Material and reactive forms.
2. Assign required validators to form controls in each step.
3. Complete the stepper steps, then use the reset() method on the stepper to reset it.
4. Observe that form controls are marked as touched or dirty even though the stepper was reset, and validation errors are displayed.
5. Alternatively, you can also use the native mat-stepper: https://material.angular.io/components/stepper/examples#stepper-errors

Expected Behavior

After calling stepper.reset(), all form controls should be reset to their initial state, marked as pristine and untouched. No validation errors should be displayed until the user interacts with the form controls again.

Actual Behavior

Calling stepper.reset() resets the stepper and form groups but marks all form controls as touched or dirty, triggering validation errors to display immediately.

Environment

• Angular: 18.1.1
• CDK/Material: 18.1.1
• Browser(s): Google Chrome(Version 127.0.6533.73 (Official Build) (arm64))
• Operating System (e.g. Windows, macOS, Ubuntu): macOS(Sonoma 14.7), Apple M1

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