Implement dynamic waits, setup methods, isolate gps tests

src/androidTest/java/de/dennisguse/opentracks/util/LiveDataTestUtils.java

@@ -0,0 +1,57 @@
+package de.dennisguse.opentracks.util;
+
+import static org.junit.Assert.fail;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.Observer;
+import androidx.test.platform.app.InstrumentationRegistry;
+
+import java.time.Duration;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Predicate;
+
+public final class LiveDataTestUtils {
+
+    private LiveDataTestUtils() {
+    }
+
+    public static <T> T waitForValue(LiveData<T> liveData,
+                                     Predicate<T> predicate,
+                                     Duration timeout,
+                                     String description) {
+        AtomicReference<T> lastValue = new AtomicReference<>(liveData.getValue());
+        CountDownLatch latch = new CountDownLatch(1);
+
+        Observer<T> observer = value -> {
+            lastValue.set(value);
+            if (predicate.test(value)) {
+                latch.countDown();
+            }
+        };
+
+        InstrumentationRegistry.getInstrumentation().runOnMainSync(() -> {
+            liveData.observeForever(observer);
+
+            T currentValue = liveData.getValue();
+            lastValue.set(currentValue);
+            if (predicate.test(currentValue)) {
+                latch.countDown();
+            }
+        });
+
+        try {
+            if (!latch.await(timeout.toMillis(), TimeUnit.MILLISECONDS)) {
+                fail("Timed out waiting for " + description + ". Last value: " + lastValue.get());
+            }
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            fail("Interrupted while waiting for " + description);
+        } finally {
+            InstrumentationRegistry.getInstrumentation().runOnMainSync(() -> liveData.removeObserver(observer));
+        }
+
+        return lastValue.get();
+    }
+}