util.time: Add brief tests

spec/util_time_spec.lua

@@ -0,0 +1,31 @@
+describe("util.time", function ()
+	local time;
+	setup(function ()
+		time = require "util.time";
+	end);
+	describe("now()", function ()
+		it("exists", function ()
+			assert.is_function(time.now);
+		end);
+		it("returns a number", function ()
+			assert.is_number(time.now());
+		end);
+	end);
+	describe("monotonic()", function ()
+		it("exists", function ()
+			assert.is_function(time.monotonic);
+		end);
+		it("returns a number", function ()
+			assert.is_number(time.monotonic());
+		end);
+		it("time goes in one direction", function ()
+			local a = time.monotonic();
+			local b	= time.monotonic();
+			assert.truthy(a <= b);
+		end);
+	end);
+end);
+
+
+
+