test: add file download E2E tests with local HTML fixtures

[chrisleewilcox]

Description

Migrates the two file download E2E tests from the quarantined browser-tests.failing.ts into a new browser-download.spec.ts file. Replaces live external URL navigation (tyschenko.github.io) with local HTML fixtures served by DappServer, eliminating external network dependencies and improving test reliability.

Part of the effort to increase API mocking coverage for E2E tests (MMQA-1368).

Changelog

CHANGELOG entry: null

Related issues

Fixes: MMQA-1705

Manual testing steps

Feature: Browser File Download

  Scenario: user downloads a blob file from a local fixture page
    Given the app is launched and user is logged in
    And the browser view is open

    When user navigates to the local blob download fixture page
    And user taps the Download button
    And user confirms the download in the tapjacking dialog
    Then the download success state is displayed

  Scenario: user downloads a base64 file from a local fixture page
    Given the app is launched and user is logged in
    And the browser view is open

    When user navigates to the local base64 download fixture page
    And user taps the Download button
    And user confirms the download in the tapjacking dialog
    Then the download success state is displayed

Screenshots/Recordings

Before

N/A — tests were quarantined in browser-tests.failing.ts due to reliance on external URLs.

After

Both tests passing locally on iOS simulator:

PASS tests/smoke/wallet/browser/browser-download.spec.ts (222.23 s)
  SmokeWalletPlatform: Browser File Download
    ✓ downloads a blob file (121368 ms)
    ✓ downloads a base64 file (92885 ms)

Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• I've completed the PR template to the best of my ability
• I've included tests if applicable
• I've documented my code using JSDoc format if applicable
• I've applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

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Note

Low Risk
Low risk because changes are limited to E2E smoke tests and static HTML/text fixtures, with no production code paths affected.

Overview
Adds a new smoke spec browser-download.spec.ts that exercises in-app browser file downloads for both blob and base64 data URL flows.

Replaces reliance on external download pages by introducing local DappServer-served fixtures (tests/fixtures/download/*) that fetch a bundled File.txt and trigger downloads via URL.createObjectURL or FileReader.readAsDataURL.

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🔍 Smart E2E Test Selection

⏭️ Smart E2E selection skipped - draft PR

All E2E tests pre-selected.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

✅ E2E Fixture Validation — Schema is up to date
16 value mismatches detected (expected — fixture represents an existing user).
View details