Support running the project from target/test-classes

[peholmst]

It is possible in Spring Boot to create a TestApplication class, that extends the configuration of the main Application class with mocks or Testcontainers. This is very useful for local development as it does not require a separate development profile:

• Run the main app with mvn spring-boot:run with real external services.
• Run the test app with mvn spring-boot:test-run with Testcontainer services (or mocks you configure).

For this to work, Vaadin must support running both from target/classes (main app) and target/test-classes(test app). This PR adds support for that.

PR vaadin/walking-skeleton#71 adds a workaround to the walking skeleton, but I think it would be better to get this into Flow directly.

[github-actions]

Test Results

1 217 files   -  17  1 217 suites   - 17   1h 13m 50s ⏱️ - 1m 34s
8 425 tests  - 117  8 366 ✅  - 120  55 💤  - 1  4 ❌ +4 
8 832 runs   -  82  8 764 ✅  -  85  64 💤  - 1  4 ❌ +4 

For more details on these failures, see this check.

Results for commit 659c8b3. ± Comparison against base commit 8be728d.

This pull request removes 117 tests.

com.vaadin.base.devserver.AbstractDevServerRunnerTest ‑ shouldPassEncodedUrlToDevServer
com.vaadin.base.devserver.AbstractDevServerRunnerTest ‑ updateServerStartupEnvironment_preferIpv4_LocalhostIpAddressAddedToProcessEnvironment
com.vaadin.base.devserver.AbstractDevServerRunnerTest ‑ updateServerStartupEnvironment_preferIpv6_LocalhostIpAddressAddedToProcessEnvironment
com.vaadin.base.devserver.BrowserLiveReloadAccessorImplTest ‑ getLiveReload_devMode_contextHasNoReloadInstance_instanceIsCreated
com.vaadin.base.devserver.BrowserLiveReloadAccessorImplTest ‑ getLiveReload_devMode_contextHasReloadInstance_instanceIsReturned
com.vaadin.base.devserver.BrowserLiveReloadAccessorImplTest ‑ getLiveReload_liveReloadDisabled_instanceIsCreated
com.vaadin.base.devserver.BrowserLiveReloadAccessorImplTest ‑ getLiveReload_productionMode_nullIsReturned
com.vaadin.base.devserver.DebugWindowConnectionTest ‑ backwardsCompatibilityClassExists
com.vaadin.base.devserver.DebugWindowConnectionTest ‑ getBackend_HotSwapVaadinIntegrationClassLoaded_returnsHOTSWAP_AGENT
com.vaadin.base.devserver.DebugWindowConnectionTest ‑ getBackend_JRebelClassEventListenerClassLoaded_returnsJREBEL
…

♻️ This comment has been updated with latest results.

[peholmst]

Converted back to draft as this change breaks several tests.

[sonarqubecloud]

Quality Gate passed

Issues
209 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