Add support for retrieving the latest release (#493)

Author: georgeorfanidi

docs/docs/repository.md

@@ -23,6 +23,8 @@ with Github4s, you can interact with:
   - [Update a File](#update-a-file)
   - [Delete a File](#delete-a-file)
 - [Releases](#releases)
+  - [List of releases](#list-of-releases)
+  - [The latest release](#the-latest-release)
   - [Create a release](#create-a-release)
 - [Statuses](#statuses)
   - [Create a status](#create-a-status)
@@ -379,6 +381,28 @@ response.result match {
 
 The `result` on the right is the corresponding [List[Release]][repository-scala].
 
+### The latest release
+
+You can get the latest release using `latestRelease`, it takes as arguments:
+
+- the repository coordinates (`owner` and `name` of the repository).
+
+Get the latest release:
+
+```scala mdoc:compile-only
+val latestRelease =
+  gh.repos.latestRelease(
+  "47deg",
+  "github4s")
+val response = latestRelease.unsafeRunSync()
+response.result match {
+  case Left(e) => println(s"Something went wrong: ${e.getMessage}")
+  case Right(r) => println(r)
+}
+```
+
+The `result` on the right is the corresponding [Option[Release]][repository-scala].
+
 ### Create a release
 
 Users with push access to the repository can create a release using `createRelease`; it takes as arguments:

github4s/src/main/scala/github4s/algebras/Repositories.scala

@@ -271,6 +271,20 @@ trait Repositories[F[_]] {
       headers: Map[String, String] = Map()
   ): F[GHResponse[List[User]]]
 
+  /**
+   * Latest release
+   *
+   * @param owner of the repo
+   * @param repo name of the repo
+   * @param headers optional user headers to include in the request
+   * @return a GHResponse with List[Release]
+   */
+  def latestRelease(
+      owner: String,
+      repo: String,
+      headers: Map[String, String] = Map()
+  ): F[GHResponse[Option[Release]]]
+
   /**
    * List of releases
    *

github4s/src/main/scala/github4s/interpreters/RepositoriesInterpreter.scala

@@ -217,6 +217,14 @@ class RepositoriesInterpreter[F[_]](implicit client: HttpClient[F], accessToken:
       pagination
     )
 
+  override def latestRelease(
+      owner: String,
+      repo: String,
+      headers: Map[String, String]
+  ): F[GHResponse[Option[Release]]] =
+    client
+      .get[Option[Release]](accessToken, s"repos/$owner/$repo/releases/latest", headers, Map.empty)
+
   override def listReleases(
       owner: String,
       repo: String,

github4s/src/test/scala/github4s/integration/ReposSpec.scala

@@ -61,6 +61,18 @@ trait ReposSpec extends BaseIntegrationSpec {
     response.statusCode shouldBe okStatusCode
   }
 
+  "Repos >> LatestRelease" should "return the expected repos when a valid org is provided" taggedAs Integration in {
+    val response = clientResource
+      .use { client =>
+        Github[IO](client, accessToken).repos
+          .latestRelease(validRepoOwner, validRepoName, headers = headerUserAgent)
+      }
+      .unsafeRunSync()
+
+    testIsRight[Option[Release]](response, r => r.nonEmpty shouldBe true)
+    response.statusCode shouldBe okStatusCode
+  }
+
   "Repos >> ListOrgRepos" should "return the expected repos when a valid org is provided" taggedAs Integration in {
     val response = clientResource
       .use { client =>

github4s/src/test/scala/github4s/unit/ReposSpec.scala

@@ -57,6 +57,20 @@ class ReposSpec extends BaseSpec {
     repos.listReleases(validRepoOwner, validRepoName, None, headers = headerUserAgent)
   }
 
+  "Repos.latestRelease" should "call to httpClient.get with the right parameters" in {
+    val response: IO[GHResponse[Option[Release]]] =
+      IO(GHResponse(Option(release).asRight, okStatusCode, Map.empty))
+
+    implicit val httpClientMock = httpClientMockGet[Option[Release]](
+      url = s"repos/$validRepoOwner/$validRepoName/releases/latest",
+      response = response
+    )
+
+    val repos = new RepositoriesInterpreter[IO]
+
+    repos.latestRelease(validRepoOwner, validRepoName, headers = headerUserAgent)
+  }
+
   "Repos.listOrgRepos" should "call to httpClient.get with the right parameters" in {
     val response: IO[GHResponse[List[Repository]]] =
       IO(GHResponse(List(repo).asRight, okStatusCode, Map.empty))