Count exposure granted to the enemy as an exposure source

spec/System/TestExposureSource_spec.lua

@@ -0,0 +1,56 @@
+describe("ExposureSource", function()
+	before_each(function()
+		newBuild()
+	end)
+
+	local function equipWhisperingIce()
+		build.itemsTab:CreateDisplayItemFromRaw([[
+			New Item
+			Permafrost Staff
+			Implicits: 0
+			Inflict Elemental Exposure on Hit, lowering Total Elemental Resistances by 60%
+		]])
+		build.itemsTab:AddDisplayItem()
+		runCallback("OnFrame")
+	end
+
+	local function canApply(element)
+		return build.calcsTab.calcsEnv.modDB:Flag(nil, "Condition:CanApply" .. element .. "Exposure") == true
+	end
+
+	local function enemyResist(element)
+		return build.calcsTab.calcsEnv.enemyDB:Sum("BASE", nil, element .. "Resist")
+	end
+
+	it("counts exposure granted directly to the enemy as a source", function()
+		equipWhisperingIce()
+
+		-- Without this the enemy is exposed while the build is told it cannot
+		-- expose, which hides the "Is the enemy Exposed" config entirely.
+		assert.is_true(build.calcsTab.calcsEnv.enemyDB:Flag(nil, "Condition:HasFireExposure") == true)
+		for _, element in ipairs({ "Fire", "Cold", "Lightning" }) do
+			assert.is_true(canApply(element))
+		end
+	end)
+
+	it("does not report a source when nothing grants exposure", function()
+		runCallback("OnFrame")
+
+		for _, element in ipairs({ "Fire", "Cold", "Lightning" }) do
+			assert.is_false(canApply(element))
+		end
+	end)
+
+	it("keeps the largest exposure when the config is also enabled", function()
+		equipWhisperingIce()
+		local itemOnly = enemyResist("Fire")
+
+		build.configTab.input.conditionEnemyFireExposure = true
+		build.configTab:BuildModList()
+		runCallback("OnFrame")
+
+		-- Exposure does not stack: the -20% from the config must not add to the
+		-- -60% from the item.
+		assert.are.equals(itemOnly, enemyResist("Fire"))
+	end)
+end)

src/Modules/CalcPerform.lua

@@ -431,6 +431,12 @@ local function doActorAttribsConditions(env, actor)
 			if modDB:Sum("BASE", nil, modName) > 0 or modDB:HasMod("FLAG", nil, "InflictExposure") then
 				return true
 			end
+			-- Exposure granted straight to the enemy, as The Whispering Ice and
+			-- "Enemies in your Presence have Exposure" do, carries no chance mod
+			-- and no InflictExposure flag, so it has to be read off the enemy.
+			if env.enemy and env.enemy.modDB and env.enemy.modDB:Sum("BASE", nil, element .. "Exposure") > 0 then
+				return true
+			end
 			for _, activeSkill in ipairs(env.player.activeSkillList) do
 				if hasActiveSkillExposureSource(activeSkill, modName) then
 					return true