fix client following api tests

Signed-off-by: Adam Ratzman <adam@adamratzman.com>

Author: adamint

src/commonMain/kotlin/com.adamratzman.spotify/SpotifyApi.kt

@@ -542,18 +542,18 @@ public open class SpotifyClientApi(
      */
     public val player: ClientPlayerApi = ClientPlayerApi(this)
 
-    private lateinit var userIdBacking: String
+    private var userIdBacking: String? = null
 
     private suspend fun initiatizeUserIdBacking(): String {
         userIdBacking = users.getClientProfile().id
-        return userIdBacking
+        return userIdBacking!!
     }
 
     /**
      * The Spotify user id to which the api instance is connected
      */
     public suspend fun getUserId(): String =
-        if (::userIdBacking.isInitialized) userIdBacking else initiatizeUserIdBacking()
+        if (userIdBacking != null) userIdBacking!! else initiatizeUserIdBacking()
 
     /**
      * The Spotify user id to which the api instance is connected

src/commonMain/kotlin/com.adamratzman.spotify/endpoints/client/ClientFollowingApi.kt

@@ -209,8 +209,8 @@ public class ClientFollowingApi(api: GenericSpotifyApi) : FollowingApi(api) {
      * with full [Artist] objects
      */
     public suspend fun getFollowedArtists(
-        limit: Int?,
-        after: String?
+        limit: Int? = api.spotifyApiOptions.defaultLimit,
+        after: String? = null
     ): CursorBasedPagingObject<Artist> = get(
         endpointBuilder("/me/following").with("type", "artist").with("limit", limit).with(
             "after",
@@ -232,8 +232,8 @@ public class ClientFollowingApi(api: GenericSpotifyApi) : FollowingApi(api) {
      * with full [Artist] objects
      */
     public fun getFollowedArtistsRestAction(
-        limit: Int?,
-        after: String?
+        limit: Int? = api.spotifyApiOptions.defaultLimit,
+        after: String? = null
     ): SpotifyRestAction<CursorBasedPagingObject<Artist>> = SpotifyRestAction { getFollowedArtists(limit, after) }
 
     /**
@@ -313,7 +313,7 @@ public class ClientFollowingApi(api: GenericSpotifyApi) : FollowingApi(api) {
      *
      * @throws BadRequestException if an invalid id is provided
      */
-    public fun followArtistRestAction(artistId: String) = SpotifyRestAction { followArtist(artistId) }
+    public fun followArtistRestAction(artistId: String): SpotifyRestAction<Unit> = SpotifyRestAction { followArtist(artistId) }
 
     /**
      * Add the current user as a follower of other artists
@@ -369,7 +369,7 @@ public class ClientFollowingApi(api: GenericSpotifyApi) : FollowingApi(api) {
      *
      * @throws BadRequestException if the playlist is not found
      */
-    public suspend fun followPlaylist(playlist: String, followPublicly: Boolean): String = put(
+    public suspend fun followPlaylist(playlist: String, followPublicly: Boolean = true): String = put(
         endpointBuilder("/playlists/${PlaylistUri(playlist).id}/followers").toString(),
         "{\"public\": $followPublicly}"
     )