fix: Fix error body conversion in NetworkResponse call

Fixes #4

Author: haroldadmin

src/main/kotlin/com/haroldadmin/cnradapter/NetworkResponseCall.kt

@@ -16,10 +16,20 @@ internal class NetworkResponseCall<S : Any, E : Any>(
         backingCall.enqueue(object : Callback<S> {
             override fun onResponse(call: Call<S>, response: Response<S>) {
                 val body = response.body()
-                if (body != null) {
-                    callback.onResponse(this@NetworkResponseCall, Response.success(NetworkResponse.Success(body, response.headers())))
+                val headers = response.headers()
+                val code = response.code()
+                val errorBody = response.errorBody()
+
+                if (response.isSuccessful) {
+                    if (body != null) {
+                        callback.onResponse(this@NetworkResponseCall, Response.success(NetworkResponse.Success(body, headers)))
+                    } else {
+                        // Response is successful but the body is null, so there's probably a server error here
+                        callback.onResponse(this@NetworkResponseCall, Response.success(NetworkResponse.ServerError(null, code, headers)))
+                    }
                 } else {
-                    callback.onResponse(this@NetworkResponseCall, Response.success(NetworkResponse.ServerError(null, response.code(), response.headers())))
+                    val convertedErrorBody = try { errorConverter.convert(errorBody) } catch (ex: Exception) { null }
+                    callback.onResponse(this@NetworkResponseCall, Response.success(NetworkResponse.ServerError(convertedErrorBody, code, headers)))
                 }
             }
 

src/test/kotlin/com/haroldadmin/cnradapter/NetworkResponseCallTest.kt

@@ -13,7 +13,7 @@ import retrofit2.*
 import java.io.IOException
 
 internal class NetworkResponseCallTest {
-    private val errorConverter = Converter<ResponseBody, String> { it.toString() }
+    private val errorConverter = Converter<ResponseBody, String> { it.string() }
     private val backingCall = CompletableCall<String>()
     private val networkResponseCall = NetworkResponseCall<String, String>(backingCall, errorConverter)
 
@@ -75,6 +75,28 @@ internal class NetworkResponseCallTest {
         backingCall.completeWithException(HttpException(Response.error<String>(404, "Server Error".toResponseBody())))
     }
 
+    @Test
+    fun `should parse error body correctly when ServerError occurs`() {
+
+        val errorBody = "An error occurred"
+        val responseCode = 404
+
+        networkResponseCall.enqueue(object: Callback<NetworkResponse<String, String>> {
+            override fun onResponse(call: Call<NetworkResponse<String, String>>, response: Response<NetworkResponse<String, String>>) {
+                with(response.body()) {
+                    this as NetworkResponse.ServerError<String>
+                    body shouldBe errorBody
+                    code shouldBe responseCode
+                }
+            }
+
+            override fun onFailure(call: Call<NetworkResponse<String, String>>, t: Throwable) {
+                throw IllegalStateException()
+            }
+        })
+        backingCall.complete(Response.error(responseCode, errorBody.toResponseBody()))
+    }
+
     @Test
     fun `should parse unsuccessful call with IOException as NetworkResponse NetworkError`() {
         networkResponseCall.enqueue(object: Callback<NetworkResponse<String, String>> {