test: 테스트 코드 작성을 위한 기본 세팅 (#255)

* feat: CoroutinesTestExtension 구현

* feat: Livedata getOrAwaitValue 구현

* feat: InstantTaskExecutorExtension 구현

* feat: TestFixture 생성

* style: ktlint 적용

android/app/src/test/java/com/zzang/chongdae/util/CoroutinesTestExtension.kt

@@ -0,0 +1,24 @@
+package com.zzang.chongdae.util
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.TestDispatcher
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.setMain
+import org.junit.jupiter.api.extension.AfterEachCallback
+import org.junit.jupiter.api.extension.BeforeEachCallback
+import org.junit.jupiter.api.extension.ExtensionContext
+
+@ExperimentalCoroutinesApi
+class CoroutinesTestExtension(
+    private val dispatcher: TestDispatcher = UnconfinedTestDispatcher(),
+) : BeforeEachCallback, AfterEachCallback {
+    override fun beforeEach(context: ExtensionContext?) {
+        Dispatchers.setMain(dispatcher)
+    }
+
+    override fun afterEach(context: ExtensionContext?) {
+        Dispatchers.resetMain()
+    }
+}

android/app/src/test/java/com/zzang/chongdae/util/GetOrAwaitValue.kt

@@ -0,0 +1,33 @@
+package com.zzang.chongdae.util
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.Observer
+import java.util.concurrent.CountDownLatch
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.TimeoutException
+
+fun <T> LiveData<T>.getOrAwaitValue(
+    time: Long = 2,
+    timeUnit: TimeUnit = TimeUnit.SECONDS,
+): T {
+    var data: T? = null
+    val latch = CountDownLatch(1)
+    val observer =
+        object : Observer<T> {
+            override fun onChanged(value: T) {
+                data = value
+                latch.countDown()
+                this@getOrAwaitValue.removeObserver(this)
+            }
+        }
+
+    this.observeForever(observer)
+
+    // Don't wait indefinitely if the LiveData is not set.
+    if (!latch.await(time, timeUnit)) {
+        throw TimeoutException("LiveData value was never set.")
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    return data as T
+}

android/app/src/test/java/com/zzang/chongdae/util/InstantTaskExecutorExtension.kt

@@ -0,0 +1,31 @@
+package com.zzang.chongdae.util
+
+import androidx.arch.core.executor.ArchTaskExecutor
+import androidx.arch.core.executor.TaskExecutor
+import org.junit.jupiter.api.extension.AfterEachCallback
+import org.junit.jupiter.api.extension.BeforeEachCallback
+import org.junit.jupiter.api.extension.ExtensionContext
+
+class InstantTaskExecutorExtension : BeforeEachCallback, AfterEachCallback {
+    override fun beforeEach(context: ExtensionContext?) {
+        ArchTaskExecutor.getInstance().setDelegate(
+            object : TaskExecutor() {
+                override fun executeOnDiskIO(runnable: Runnable) {
+                    runnable.run()
+                }
+
+                override fun postToMainThread(runnable: Runnable) {
+                    runnable.run()
+                }
+
+                override fun isMainThread(): Boolean {
+                    return true
+                }
+            },
+        )
+    }
+
+    override fun afterEach(context: ExtensionContext?) {
+        ArchTaskExecutor.getInstance().setDelegate(null)
+    }
+}

android/app/src/test/java/com/zzang/chongdae/util/TestFixture.kt

@@ -0,0 +1,3 @@
+package com.zzang.chongdae.util
+
+object TestFixture