Fix typo in CanTrade.

Introduced in c917c39a0d.
Reported by @gameboy at
https://wildfiregames.com/forum/topic/107586-an-error-occurred/?do=findComment&comment=553753.

Also adds a small test.

Differential revision: https://code.wildfiregames.com/D5060
Reviewed by: @wraitii
This was SVN commit r27737.

binaries/data/mods/public/simulation/components/Trader.js

@@ -167,24 +167,23 @@ Trader.prototype.HasBothMarkets = function()
 
 Trader.prototype.CanTrade = function(target)
 {
-	let cmpTraderIdentity = Engine.QueryInterface(this.entity, IID_Identity);
-
-	let cmpTargetMarket = QueryMiragedInterface(target, IID_Market);
+	const cmpTargetMarket = QueryMiragedInterface(target, IID_Market);
 	if (!cmpTargetMarket)
 		return false;
 
-	let cmpTargetFoundation = Engine.QueryInterface(target, IID_Foundation);
+	const cmpTargetFoundation = Engine.QueryInterface(target, IID_Foundation);
 	if (cmpTargetFoundation)
 		return false;
 
+	const cmpTraderIdentity = Engine.QueryInterface(this.entity, IID_Identity);
 	if (!(cmpTraderIdentity.HasClass("Organic") && cmpTargetMarket.HasType("land")) &&
 		!(cmpTraderIdentity.HasClass("Ship") && cmpTargetMarket.HasType("naval")))
 		return false;
 
-	let cmpTraderDiplomacy = QueryOwnerInterface(this.entity, IID_Diplomacy);
-	let cmpTargetPlayer = QueryOwnerInterface(target, IID_Player);
+	const cmpTraderDiplomacy = QueryOwnerInterface(this.entity, IID_Diplomacy);
+	const cmpTargetPlayer = QueryOwnerInterface(target, IID_Player);
 
-	return cmpTraderPlayer && cmpTargetPlayer && !cmpTraderDiplomacy.IsEnemy(cmpTargetPlayer.GetPlayerID());
+	return cmpTraderDiplomacy && cmpTargetPlayer && !cmpTraderDiplomacy.IsEnemy(cmpTargetPlayer.GetPlayerID());
 };
 
 Trader.prototype.AddResources = function(ent, gain)

binaries/data/mods/public/simulation/components/tests/test_Trader.js

@@ -0,0 +1,96 @@
+Engine.LoadComponentScript("interfaces/Diplomacy.js");
+Engine.LoadComponentScript("interfaces/Foundation.js");
+Engine.LoadComponentScript("interfaces/Market.js");
+Engine.LoadComponentScript("interfaces/Trader.js");
+Engine.LoadComponentScript("Trader.js");
+Engine.LoadHelperScript("Player.js");
+
+const player = 1;
+const enemy = 2;
+const ally = 3;
+const trader = 5;
+const ownMarket = 6;
+const otherMarket = 7;
+
+AddMock(SYSTEM_ENTITY, IID_PlayerManager, {
+        "GetPlayerByID": (i) => i
+});
+
+const cmpTrader = ConstructComponent(trader, "Trader", {
+	"GainMultiplier": 0.8,
+	"GarrisonGainMultiplier": 0.2
+});
+
+AddMock(trader, IID_Identity, {
+	"HasClass": (cls) => cls === "Organic",
+});
+
+AddMock(ownMarket, IID_Market, {
+	"HasType": (t) => t === "land"
+});
+
+AddMock(trader, IID_Ownership, {
+	"GetOwner": () => player
+});
+
+AddMock(ownMarket, IID_Ownership, {
+	"GetOwner": () => player
+});
+
+AddMock(player, IID_Player, {
+	"GetPlayerID": () => player,
+});
+
+AddMock(player, IID_Diplomacy, {
+	"IsEnemy": (id) => id === enemy,
+});
+
+TS_ASSERT(cmpTrader.CanTrade(ownMarket));
+
+// We can't trade with our enemy.
+AddMock(enemy, IID_Player, {
+	"GetPlayerID": () => enemy,
+});
+
+AddMock(otherMarket, IID_Ownership, {
+	"GetOwner": () => enemy
+});
+
+AddMock(otherMarket, IID_Market, {
+	"HasType": (t) => t === "land"
+});
+
+TS_ASSERT(!cmpTrader.CanTrade(otherMarket));
+
+// But can with our ally.
+AddMock(ally, IID_Player, {
+	"GetPlayerID": () => ally,
+});
+
+AddMock(otherMarket, IID_Ownership, {
+	"GetOwner": () => ally
+});
+
+TS_ASSERT(cmpTrader.CanTrade(otherMarket));
+
+// Land traders shouldn't try to trade with naval-only markets.
+AddMock(trader, IID_Identity, {
+	"HasClass": (cls) => cls === "Organic",
+});
+
+AddMock(ownMarket, IID_Market, {
+	"HasType": (t) => t === "naval"
+});
+
+TS_ASSERT(!cmpTrader.CanTrade(ownMarket));
+
+// And Ships shouldn't try to trade with land markets.
+AddMock(trader, IID_Identity, {
+	"HasClass": (cls) => cls === "Ship",
+});
+
+AddMock(ownMarket, IID_Market, {
+	"HasType": (t) => t === "land"
+});
+
+TS_ASSERT(!cmpTrader.CanTrade(ownMarket));