test:implement unit tests for fetching campaigns and fix DTO mocking logic

app/src/test/kotlin/fr/free/nrw/commons/OkHttpJsonApiClientTests.kt

@@ -3,6 +3,10 @@ package fr.free.nrw.commons
 import com.google.gson.Gson
 import com.nhaarman.mockitokotlin2.any
 import com.nhaarman.mockitokotlin2.verify
+import com.nhaarman.mockitokotlin2.times
+import fr.free.nrw.commons.campaigns.CampaignResponseDTO
+import fr.free.nrw.commons.campaigns.CampaignConfig
+import fr.free.nrw.commons.campaigns.models.Campaign
 import fr.free.nrw.commons.explore.depictions.DepictsClient
 import fr.free.nrw.commons.location.LatLng
 import fr.free.nrw.commons.mwapi.OkHttpJsonApiClient
@@ -10,13 +14,22 @@ import fr.free.nrw.commons.nearby.model.NearbyQueryParams
 import okhttp3.Call
 import okhttp3.HttpUrl
 import okhttp3.OkHttpClient
+import okhttp3.Request
 import okhttp3.Response
+import okhttp3.ResponseBody
+import okhttp3.mockwebserver.MockResponse
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertTrue
 import org.junit.Before
 import org.junit.Test
 import org.mockito.Mock
 import org.mockito.Mockito
-import org.mockito.Mockito.times
+import org.mockito.Mockito.eq
 import org.mockito.MockitoAnnotations
+import java.io.BufferedReader
+import java.io.InputStreamReader
 import java.lang.Exception
 
 class OkHttpJsonApiClientTests {
@@ -45,34 +58,43 @@ class OkHttpJsonApiClientTests {
     @Mock
     lateinit var response: Response
 
+    @Mock
+    lateinit var responseBody: ResponseBody
+
+    private lateinit var mockWebServer: TestWebServer
+
     @Before
     fun setUp() {
         MockitoAnnotations.openMocks(this)
-        okHttpJsonApiClient =
+        mockWebServer = TestWebServer()
-            OkHttpJsonApiClient(
+        mockWebServer.setUp()
-                okhttpClient,
+        okHttpJsonApiClient = OkHttpJsonApiClient(
-                depictsClient,
+            okhttpClient,
-                wikiMediaToolforgeUrl,
+            depictsClient,
-                sparqlQueryUrl,
+            wikiMediaToolforgeUrl,
-                campaignsUrl,
+            sparqlQueryUrl,
-                gson,
+            mockWebServer.getUrl(), //use the mock server for the campaignsUrl
-            )
+            gson
+        )
         Mockito.`when`(okhttpClient.newCall(any())).thenReturn(call)
         Mockito.`when`(call.execute()).thenReturn(response)
+        Mockito.`when`(response.isSuccessful).thenReturn(false)
+        Mockito.`when`(response.message).thenReturn("test")
+        Mockito.`when`(response.body).thenReturn(responseBody)
+        Mockito.`when`(responseBody.string()).thenReturn("{\"error\": \"test\"}")
     }
 
     @Test
     fun testGetNearbyPlacesCustomQuery() {
-        Mockito.`when`(response.message).thenReturn("test")
         try {
             okHttpJsonApiClient.getNearbyPlaces(latLng, "test", 10.0, "test")
         } catch (e: Exception) {
-            assert(e.message.equals("test"))
+            assertEquals("test", e.message)
         }
         try {
             okHttpJsonApiClient.getNearbyPlaces(NearbyQueryParams.Rectangular(latLng, latLng), "test", true, "test")
         } catch (e: Exception) {
-            assert(e.message.equals("test"))
+            assertEquals("test", e.message)
         }
         verify(okhttpClient, times(2)).newCall(any())
         verify(call, times(2)).execute()
@@ -80,11 +102,10 @@ class OkHttpJsonApiClientTests {
 
     @Test
     fun testGetNearbyPlaces() {
-        Mockito.`when`(response.message).thenReturn("test")
         try {
             okHttpJsonApiClient.getNearbyPlaces(latLng, "test", 10.0, null)
         } catch (e: Exception) {
-            assert(e.message.equals("test"))
+            assertEquals("test", e.message)
         }
         try {
             okHttpJsonApiClient.getNearbyPlaces(
@@ -93,9 +114,8 @@ class OkHttpJsonApiClientTests {
                 true,
                 null
             )
-
         } catch (e: Exception) {
-            assert(e.message.equals("test"))
+            assertEquals("test", e.message)
         }
         try {
             okHttpJsonApiClient.getNearbyPlaces(
@@ -105,7 +125,7 @@ class OkHttpJsonApiClientTests {
                 null
             )
         } catch (e: Exception) {
-            assert(e.message.equals("test"))
+            assertEquals("test", e.message)
         }
         verify(okhttpClient, times(3)).newCall(any())
         verify(call, times(3)).execute()
@@ -113,18 +133,121 @@ class OkHttpJsonApiClientTests {
 
     @Test
     fun testGetNearbyItemCount() {
-        Mockito.`when`(response.message).thenReturn("test")
         try {
             okHttpJsonApiClient.getNearbyItemCount(NearbyQueryParams.Radial(latLng, 10f))
         } catch (e: Exception) {
-            assert(e.message.equals("test"))
+            assertEquals("test", e.message)
         }
         try {
             okHttpJsonApiClient.getNearbyItemCount(NearbyQueryParams.Rectangular(latLng, latLng))
         } catch (e: Exception) {
-            assert(e.message.equals("test"))
+            assertEquals("test", e.message)
         }
         verify(okhttpClient, times(2)).newCall(any())
         verify(call, times(2)).execute()
     }
+
+    @Test
+    fun testGetCampaignsWithData() {
+        //loads the json response from resources
+        val jsonResponse = loadJsonFromResource("campaigns_response_with_data.json")
+
+        //mocks the succesfull response chain
+        Mockito.`when`(response.isSuccessful).thenReturn(true)
+        Mockito.`when`(response.message).thenReturn("OK")
+        Mockito.`when`(response.body).thenReturn(responseBody)
+        Mockito.`when`(responseBody.string()).thenReturn(jsonResponse)
+
+        val campaignResponse = CampaignResponseDTO().apply {
+            campaignConfig = CampaignConfig().apply {
+                showOnlyLiveCampaigns = false
+                sortBy = "startDate"
+            }
+            campaigns = listOf(
+                Campaign().apply {
+                    title = "Wiki Loves Monuments"
+                    isWLMCampaign = true
+                },
+                Campaign().apply {
+                    title = "Wiki Loves Nature"
+                    isWLMCampaign = false
+                }
+            )
+        }
+
+        //any() for the string argument and eq() for the class argument.
+        Mockito.`when`(
+            gson.fromJson(
+                any<String>(),
+                eq(CampaignResponseDTO::class.java)
+            )
+        ).thenReturn(campaignResponse)
+
+        //call the getCampaigns
+        val result: CampaignResponseDTO? = okHttpJsonApiClient.getCampaigns().blockingGet()
+
+        //verify the  results
+        assertNotNull(result)
+        assertNotNull(result?.campaigns)
+        assertEquals(2, result?.campaigns!!.size)
+        assertEquals("Wiki Loves Monuments", result.campaigns!![0].title)
+        assertTrue(result.campaigns!![0].isWLMCampaign)
+        assertEquals("Wiki Loves Nature", result.campaigns!![1].title)
+        assertEquals(false, result.campaigns!![1].isWLMCampaign)
+        assertNotNull(result.campaignConfig)
+        assertFalse(result.campaignConfig!!.showOnlyLiveCampaigns)
+        assertEquals("startDate", result.campaignConfig!!.sortBy)
+    }
+
+    @Test
+    fun testGetCampaignsEmpty() {
+        //loads the empty json response
+        val jsonResponse = loadJsonFromResource("campaigns_response_empty.json")
+
+        //mocks the successful response chain
+        Mockito.`when`(response.isSuccessful).thenReturn(true)
+        Mockito.`when`(response.message).thenReturn("OK")
+        Mockito.`when`(response.body).thenReturn(responseBody)
+        Mockito.`when`(responseBody.string()).thenReturn(jsonResponse)
+
+        val campaignResponse = CampaignResponseDTO().apply {
+            campaignConfig = CampaignConfig().apply {
+                showOnlyLiveCampaigns = false
+                sortBy = "startDate"
+            }
+            campaigns = emptyList()
+        }
+
+        //use any() for the string argument and eq() for the class argument.
+        Mockito.`when`(
+            gson.fromJson(
+                any<String>(),
+                eq(CampaignResponseDTO::class.java)
+            )
+        ).thenReturn(campaignResponse)
+
+        //calls getCampaigns
+        val result: CampaignResponseDTO? = okHttpJsonApiClient.getCampaigns().blockingGet()
+
+        //verify the results
+        assertNotNull(result)
+        assertNotNull(result?.campaigns)
+        assertTrue(result?.campaigns!!.isEmpty())
+        assertNotNull(result.campaignConfig)
+        assertFalse(result.campaignConfig!!.showOnlyLiveCampaigns)
+        assertEquals("startDate", result.campaignConfig!!.sortBy)
+    }
+
+    fun loadJsonFromResource(fileName: String): String {
+        val resourcePath = "raw/$fileName"
+        //use the classloader to find the resource in the test environment
+        val inputStream = javaClass.classLoader?.getResourceAsStream(resourcePath)
+
+        if (inputStream != null) {
+            //reads the entire stream content
+            return BufferedReader(InputStreamReader(inputStream)).use { it.readText() }
+        }
+        //throws an exception with the correct expected path
+        throw IllegalArgumentException("Resource $fileName not found. Please ensure the file is located in app/src/test/resources/raw/")
+    }
 }