Add possibility for mock api to return errors at a certain frequency

Author: LukasLechnerDev

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/usecases/flow/usecase2/MockApiBehavior.kt

@@ -13,6 +13,7 @@ fun mockApi(context: Context) =
                 path = "/current-stock-prices",
                 body = { Gson().toJson(fakeCurrentStockPrices(context)) },
                 status = 200,
-                delayInMs = 1500
+                delayInMs = 1500,
+                errorFrequencyInPercent = 50
             )
     )

app/src/main/java/com/lukaslechner/coroutineusecasesonandroid/utils/MockNetworkInterceptor.kt

@@ -2,6 +2,7 @@ package com.lukaslechner.coroutineusecasesonandroid.utils
 
 import com.google.gson.Gson
 import okhttp3.*
+import kotlin.random.Random
 
 class MockNetworkInterceptor : Interceptor {
 
@@ -18,12 +19,25 @@ class MockNetworkInterceptor : Interceptor {
         simulateNetworkDelay(mockResponse)
 
         return if (mockResponse.status < 400) {
-            createSuccessResponse(mockResponse, request)
+
+            if (mockResponse.errorFrequencyInPercent == 0) {
+                createSuccessResponse(mockResponse, request)
+            } else {
+                maybeReturnErrorResponse(mockResponse, request)
+            }
         } else {
             createErrorResponse(request)
         }
     }
 
+    private fun maybeReturnErrorResponse(
+        mockResponse: MockResponse,
+        request: Request
+    ) = when (Random.nextInt(0, 101)) {
+        in 0..mockResponse.errorFrequencyInPercent -> createErrorResponse(request)
+        else -> createSuccessResponse(mockResponse, request)
+    }
+
     private fun findMockResponseInList(request: Request): MockResponse? {
         return mockResponses.find { mockResponse ->
             mockResponse.path.contains(request.url().encodedPath())
@@ -78,15 +92,17 @@ class MockNetworkInterceptor : Interceptor {
         body: () -> String,
         status: Int,
         delayInMs: Long = 250,
-        persist: Boolean = true
+        persist: Boolean = true,
+        errorFrequencyInPercent:Int = 0
     ) = apply {
         val mockResponse =
             MockResponse(
                 path,
                 body,
                 status,
                 delayInMs,
-                persist
+                persist,
+                errorFrequencyInPercent
             )
         mockResponses.add(mockResponse)
     }
@@ -101,5 +117,6 @@ data class MockResponse(
     val body: () -> String,
     val status: Int,
     val delayInMs: Long,
-    val persist: Boolean
+    val persist: Boolean,
+    val errorFrequencyInPercent: Int
 )