Completed

app/build.gradle.kts

@@ -79,6 +79,7 @@ dependencies {
     androidTestImplementation("androidx.test.espresso:espresso-core:3.6.1")
     androidTestImplementation("androidx.test.ext:junit:1.2.1")
     testImplementation("junit:junit:4.13.2")
+    testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.10.1")
 
     debugImplementation("androidx.compose.ui:ui-test-manifest")
     debugImplementation("androidx.compose.ui:ui-tooling")

app/src/main/java/com/example/racetracker/ui/RaceParticipant.kt

@@ -15,9 +15,12 @@
  */
 package com.example.racetracker.ui
 
+import android.util.Log
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
+import kotlinx.coroutines.delay
+import kotlin.coroutines.cancellation.CancellationException
 
 /**
  * This class represents a state holder for race participant.
@@ -47,6 +50,18 @@ class RaceParticipant(
     fun reset() {
         currentProgress = 0
     }
+
+    suspend fun run() {
+        try {
+            while (currentProgress < maxProgress) {
+                delay(progressDelayMillis)
+                currentProgress += progressIncrement
+            }
+        } catch (e: CancellationException) {
+            Log.e("RaceParticipant", "$name: ${e.message}")
+            throw e
+        }
+    }
 }
 
 /**

app/src/main/java/com/example/racetracker/ui/RaceTrackerApp.kt

@@ -36,6 +36,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
@@ -51,6 +52,8 @@ import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.tooling.preview.Preview
 import com.example.racetracker.R
 import com.example.racetracker.ui.theme.RaceTrackerTheme
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.launch
 
 @Composable
 fun RaceTrackerApp() {
@@ -67,6 +70,16 @@ fun RaceTrackerApp() {
     }
     var raceInProgress by remember { mutableStateOf(false) }
 
+    if (raceInProgress) {
+        LaunchedEffect(playerOne, playerTwo) {
+            coroutineScope {
+                launch { playerOne.run() }
+                launch { playerTwo.run() }
+            }
+            raceInProgress = false
+        }
+    }
+
     RaceTrackerScreen(
         playerOne = playerOne,
         playerTwo = playerTwo,

app/src/test/java/com/example/racetracker/RaceParticipantTest.kt

@@ -16,6 +16,13 @@
 package com.example.racetracker
 
 import com.example.racetracker.ui.RaceParticipant
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.advanceTimeBy
+import kotlinx.coroutines.test.runCurrent
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Test
 
 class RaceParticipantTest {
     private val raceParticipant = RaceParticipant(
@@ -25,4 +32,26 @@ class RaceParticipantTest {
         initialProgress = 0,
         progressIncrement = 1
     )
+
+    @OptIn(ExperimentalCoroutinesApi::class)
+    @Test
+    fun raceParticipant_RaceStarted_ProgressUpdated() = runTest {
+        val expectedProgress = 1
+
+        launch {
+            raceParticipant.run()
+        }
+        advanceTimeBy(raceParticipant.progressDelayMillis)
+        runCurrent()
+        assertEquals(expectedProgress, raceParticipant.currentProgress)
+    }
+
+    @OptIn(ExperimentalCoroutinesApi::class)
+    @Test
+    fun raceParticipant_RaceFinished_ProgressUpdate() = runTest {
+        launch { raceParticipant.run() }
+        advanceTimeBy(raceParticipant.maxProgress * raceParticipant.progressDelayMillis)
+        runCurrent()
+        assertEquals(100, raceParticipant.currentProgress)
+    }
 }