Test Downloader with HttpURLConnection backend

.gitignore

@@ -1 +1,2 @@
+docker/static-files/100MB.bin*
 target/

docker-compose.yml

@@ -0,0 +1,6 @@
+version: '3'
+services:
+  static-files:
+    build: docker/static-files
+    ports:
+      - 8088:80

docker/static-files/Dockerfile

@@ -0,0 +1,6 @@
+FROM nginx:stable
+
+COPY ./100MB.bin /var/www/100MB.bin
+COPY ./nginx.conf /etc/nginx/conf.d/default.conf
+
+CMD ["nginx", "-g", "daemon off;"]

docker/static-files/nginx.conf

@@ -0,0 +1,9 @@
+server {
+    listen 80;
+    server_name _;
+
+    root /var/www/;
+
+    location / {
+    }
+}

docker/static-files/pre_build.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+
+dd if=/dev/random of=$DIR/100MB.bin bs=1024 count=1024
+shasum $DIR/100MB.bin | awk '{print $1}' > $DIR/100MB.bin.shasum

fetch-file/src/main/scala/vdx/fetchfile/Downloader.scala

@@ -20,6 +20,7 @@ trait Downloader[F[_]] {
 }
 
 object Downloader {
+
   def apply[F[_]: Concurrent: ContextShift]: Downloader[F] = new Downloader[F] {
     def fetch(
       url: URL,

fetch-file/src/main/scala/vdx/fetchfile/HttpURLConnectionBackend.scala

@@ -0,0 +1,19 @@
+package vdx.fetchfile
+
+import cats.effect.{Resource, Sync}
+import java.net.HttpURLConnection
+
+object HttpURLConnectionBackend {
+  def apply[F[_]: Sync]: Backend[F] =
+    url => Resource.fromAutoCloseable {
+      Sync[F].delay {
+        val connection = url.openConnection().asInstanceOf[HttpURLConnection]
+        connection.setRequestProperty(
+          "User-Agent",
+          "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11"
+        )
+        connection.connect()
+        connection.getInputStream()
+      }
+    }
+}

fetch-file/src/main/scala/vdx/fetchfile/package.scala

@@ -1,27 +1,11 @@
 package vdx
 
-import cats.effect.{Resource, Sync}
+import cats.effect.Resource
 
+import java.net.URL
 import java.io.InputStream
-import java.net.{HttpURLConnection, URL}
 
 package object fetchfile {
 
   type Backend[F[_]] = URL => Resource[F, InputStream]
-
-  object Backend {
-    implicit def httpUrlConnectionBackend[F[_]: Sync]: Backend[F] =
-      url => Resource.fromAutoCloseable {
-        Sync[F].delay {
-          val connection = url.openConnection().asInstanceOf[HttpURLConnection]
-          connection.setRequestProperty(
-            "User-Agent",
-            "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11"
-          )
-          connection.connect()
-          connection.getInputStream()
-        }
-      }
-
-  }
 }

fetch-file/src/test/scala/vdx/fetchfile/DownloaderSpec.scala

@@ -5,11 +5,13 @@ import fs2._
 import org.scalatest.flatspec.AnyFlatSpec
 import org.scalatest.matchers.should.Matchers
 
-import java.io.{ByteArrayInputStream}
+import java.io.{ByteArrayInputStream, ByteArrayOutputStream}
 import java.net.URL
-import java.io.ByteArrayOutputStream
+import scala.io.Source
+import java.security.MessageDigest
 
 class DownloaderSpec extends AnyFlatSpec with Matchers {
+
   implicit val cs: ContextShift[IO] = IO.contextShift(scala.concurrent.ExecutionContext.global)
 
   "fetch" should "use the given backend to create the input stream" in {
@@ -34,5 +36,34 @@ class DownloaderSpec extends AnyFlatSpec with Matchers {
       } yield content
     }).unsafeRunSync() should be("http://example.com/test.file")
   }
+
+  it should "download the file correctly with the provided backend" in {
+    val downloader = Downloader[IO]
+
+    val downloadedBytes = (Blocker[IO].use { blocker =>
+      implicit val backend = HttpURLConnectionBackend[IO]
+      val out = new ByteArrayOutputStream()
+      for {
+        _ <- downloader.fetch(
+          new URL("http://localhost:8088/100MB.bin"),
+          Resource.fromAutoCloseable(IO.delay(out)),
+          blocker,
+          1024 * 64,
+          (s: Stream[IO, Byte]) => s.map(_ => ())
+        )
+        content <- IO.delay(out.toByteArray())
+      } yield content
+    }).unsafeRunSync()
+
+    downloadedBytes.length should be(1024 * 1024)
+    val expectedShaSum = Source.fromFile("docker/static-files/100MB.bin.shasum").mkString.trim()
+
+    val shaSum = MessageDigest.getInstance("SHA-1")
+      .digest(downloadedBytes)
+      .map("%02x".format(_))
+      .mkString
+
+    shaSum should be(expectedShaSum)
+  }
 }