Add Hydrate unit tests

test/Instances/Hydrate.spec.lua

@@ -0,0 +1,33 @@
+local Package = game:GetService("ReplicatedStorage").Fusion
+local Hydrate = require(Package.Instances.Hydrate)
+
+return function()
+	it("should return the instance it was passed", function()
+		local ins = Instance.new("Folder")
+
+		expect(Hydrate(ins) {}).to.equal(ins)
+	end)
+
+	it("should apply properties to the instance", function()
+		local ins = Instance.new("Folder")
+
+		Hydrate(ins) {
+			Name = "Jeremy"
+		}
+
+		expect(ins.Name).to.equal("Jeremy")
+	end)
+
+	it("should not inhibit garbage collection", function()
+		local ref = setmetatable({}, {__mode = "v"})
+		do
+			ref[1] = Hydrate(Instance.new("Folder")) {}
+		end
+
+		local startTime = os.clock()
+		repeat
+			task.wait()
+		until ref[1] == nil or os.clock() > startTime + 5
+		expect(ref[1]).to.equal(nil)
+	end)
+end