Utility class to use mock web server in our tests

MockWebServerTest.kt

import com.google.gson.Gson
import com.google.gson.JsonElement
import com.google.gson.JsonParser
import okhttp3.Headers
import okhttp3.mockwebserver.MockResponse
import okhttp3.mockwebserver.MockWebServer
import okhttp3.mockwebserver.RecordedRequest
import org.apache.commons.io.FileUtils
import org.junit.After
import java.io.File

open class MockWebServerTest {
    private val server: MockWebServer = MockWebServer()
    val baseUrl = server.url("/").toString()

    companion object {
        const val GET = "GET"
        const val POST = "POST"
        const val DELETE = "DELETE"
        const val PUT = "PUT"
        private const val FILE_ENCODING = "UTF-8"
        private const val QUERY_PARAM_DELIMITER = "?"
        private val parser = JsonParser()
        private val gson = Gson()
    }

    @After
    open fun tearDown() {
        server.shutdown()
    }

    private val lastRequest: RecordedRequest by lazy { server.takeRequest() }
    private val body: String by lazy { lastRequest.body.readUtf8() }
    private val formParams: Map<String, String> by lazy {
        body.split("&").map { field ->
            val parts = field.split("=")
            parts[0] to parts[1]
        }.toMap()
    }

    val requestMethod: String
        get() = lastRequest.method

    val requestPath: String
        get() {
            val path = lastRequest.path.replace("//", "/")
            return if (path.contains(QUERY_PARAM_DELIMITER)) {
                path.substring(0, path.indexOf(QUERY_PARAM_DELIMITER))
            } else {
                path
            }
        }

    val requestHeaders: Headers
        get() = lastRequest.headers

    val requestBody: JsonElement
        get() = parser.parse(lastRequest.body.readUtf8())

    val requestUrlSegments: List<String>
        get() = lastRequest.requestUrl.pathSegments()

    fun requestFormParam(value: String): String {
        return formParams[value]!!
    }

    fun requestQueryParam(value: String): String {
        return lastRequest.requestUrl.queryParameter(value)!!
    }

    fun enqueueApiResponse(statusCode: Int = 200, body: Any? = null) {
        val response = MockResponse()
        response.setResponseCode(statusCode)
        if (body != null) {
            val jsonBody = gson.toJson(body)
            response.setBody(jsonBody)
        }

        server.enqueue(response)
    }

    fun enqueueBadRequestResponse() {
        enqueueApiResponse(400)
    }

    fun enqueueUnauthorizedResponse() {
        enqueueApiResponse(401)
    }

    fun enqueueForbiddenResponse() {
        enqueueApiResponse(403)
    }

    fun enqueueServerErrorResponse() {
        enqueueApiResponse(500)
    }

    fun enqueueNotFoundResponse() {
        enqueueApiResponse(404)
    }

    fun jsonFromFile(path: String): JsonElement =
        parser.parse(getContentFromFile(path))

    private fun getContentFromFile(path: String? = null): String {
        if (path == null) {
            return ""
        }

        val file = File(javaClass.getResource(path)!!.file)
        val lines = FileUtils.readLines(file, FILE_ENCODING)
        val stringBuilder = StringBuilder()
        for (line in lines) {
            stringBuilder.append(line)
        }
        return stringBuilder.toString()
    }
}