build: fetch Robolectric's Android SDK jar from the mirror

Robolectric resolves android-all-instrumented itself at test time with
MavenArtifactFetcher, whose default repository is repo1.maven.org. The
Gradle mirror in settings.gradle.kts never applied to that fetch, so the
CI egress IP still got HTTP 429 there.

That fetcher also stores the jar in ~/.m2/repository, outside the
~/.gradle/caches directory CI restores, so every ephemeral runner
downloaded it again. Point robolectric.dependency.repo.url at the same
mirror for every Test task and cache the Robolectric Maven repository in
both workflows, keyed by the Robolectric version and the configured SDK.

.github/actions/build/action.yml

@@ -40,6 +40,11 @@ runs:
         path: ~/.gradle/caches
         key: gradle-v2-${{ hashFiles('**/*.gradle*', '**/gradle.properties', 'gradle/libs.versions.toml', 'gradle/wrapper/gradle-wrapper.properties') }}
         restore-keys: gradle-v2-
+    - uses: actions/cache@v6
+      with:
+        path: ~/.m2/repository/org/robolectric
+        key: robolectric-m2-v1-${{ hashFiles('gradle/libs.versions.toml', 'app/src/test/resources/robolectric.properties') }}
+        restore-keys: robolectric-m2-v1-
     - id: signing
       if: inputs.sign == 'true'
       shell: bash

app/build.gradle.kts

@@ -181,6 +181,8 @@ val demoScreenshotClass = "com.subtracks.ui.DemoScreenshotTest"
 val queryTimingClass = "com.subtracks.data.db.QueryTimingMeasurementTest"
 
 tasks.withType<Test>().configureEach {
+    // Robolectric fetches its Android SDK jar itself, outside Gradle's repositories.
+    systemProperty("robolectric.dependency.repo.url", providers.gradleProperty("mavenCentralMirrorUrl").get())
     if (name.endsWith("UnitTest")) {
         filter {
             (integrationTestClasses + demoScreenshotClass + queryTimingClass).forEach { excludeTestsMatching(it) }

gradle.properties

@@ -9,3 +9,5 @@ android.useAndroidX=true
 android.nonTransitiveRClass=true
 
 kotlin.code.style=official
+
+mavenCentralMirrorUrl=https://maven-central.storage-download.googleapis.com/maven2/

settings.gradle.kts

@@ -1,4 +1,5 @@
 pluginManagement {
+    val mavenCentralMirrorUrl = providers.gradleProperty("mavenCentralMirrorUrl").get()
     repositories {
         google {
             content {
@@ -7,7 +8,7 @@ pluginManagement {
                 includeGroupByRegex("androidx.*")
             }
         }
-        maven("https://maven-central.storage-download.googleapis.com/maven2/") {
+        maven(mavenCentralMirrorUrl) {
             name = "MavenCentralMirror"
         }
         mavenCentral()
@@ -19,7 +20,7 @@ dependencyResolutionManagement {
     repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
     repositories {
         google()
-        maven("https://maven-central.storage-download.googleapis.com/maven2/") {
+        maven(providers.gradleProperty("mavenCentralMirrorUrl").get()) {
             name = "MavenCentralMirror"
         }
         mavenCentral()