1 files changed, 150 insertions, 0 deletions
diff --git a/spec/util_throttle_spec.lua b/spec/util_throttle_spec.lua
new file mode 100644
index 00000000..75daf1b9
--- /dev/null
+++ b/spec/util_throttle_spec.lua
@@ -0,0 +1,150 @@
+
+
+-- Mock util.time
+local now = 0; -- wibbly-wobbly... timey-wimey... stuff
+local function later(n)
+	now = now + n; -- time passes at a different rate
+end
+package.loaded["util.time"] = {
+	now = function() return now; end
+}
+
+
+local throttle = require "util.throttle";
+
+describe("util.throttle", function()
+	describe("#create()", function()
+		it("should be created with correct values", function()
+			now = 5;
+			local a = throttle.create(3, 10);
+			assert.same(a, { balance = 3, max = 3, rate = 0.3, t = 5 });
+
+			local a = throttle.create(3, 5);
+			assert.same(a, { balance = 3, max = 3, rate = 0.6, t = 5 });
+
+			local a = throttle.create(1, 1);
+			assert.same(a, { balance = 1, max = 1, rate = 1, t = 5 });
+
+			local a = throttle.create(10, 10);
+			assert.same(a, { balance = 10, max = 10, rate = 1, t = 5 });
+
+			local a = throttle.create(10, 1);
+			assert.same(a, { balance = 10, max = 10, rate = 10, t = 5 });
+		end);
+	end);
+
+	describe("#update()", function()
+		it("does nothing when no time has passed, even if balance is not full", function()
+			now = 5;
+			local a = throttle.create(10, 10);
+			for i=1,5 do
+				a:update();
+				assert.same(a, { balance = 10, max = 10, rate = 1, t = 5 });
+			end
+			a.balance = 0;
+			for i=1,5 do
+				a:update();
+				assert.same(a, { balance = 0, max = 10, rate = 1, t = 5 });
+			end
+		end);
+		it("updates only time when time passes but balance is full", function()
+			now = 5;
+			local a = throttle.create(10, 10);
+			for i=1,5 do
+				later(5);
+				a:update();
+				assert.same(a, { balance = 10, max = 10, rate = 1, t = 5 + i*5 });
+			end
+		end);
+		it("updates balance when balance has room to grow as time passes", function()
+			now = 5;
+			local a = throttle.create(10, 10);
+			a.balance = 0;
+			assert.same(a, { balance = 0, max = 10, rate = 1, t = 5 });
+
+			later(1);
+			a:update();
+			assert.same(a, { balance = 1, max = 10, rate = 1, t = 6 });
+
+			later(3);
+			a:update();
+			assert.same(a, { balance = 4, max = 10, rate = 1, t = 9 });
+
+			later(10);
+			a:update();
+			assert.same(a, { balance = 10, max = 10, rate = 1, t = 19 });
+		end);
+		it("handles 10 x 0.1s updates the same as 1 x 1s update ", function()
+			now = 5;
+			local a = throttle.create(1, 1);
+
+			a.balance = 0;
+			later(1);
+			a:update();
+			assert.same(a, { balance = 1, max = 1, rate = 1, t = now });
+
+			a.balance = 0;
+			for i=1,10 do
+				later(0.1);
+				a:update();
+			end
+			assert(math.abs(a.balance - 1) < 0.0001); -- incremental updates cause rouding errors
+		end);
+	end);
+
+	-- describe("po")
+
+	describe("#poll()", function()
+		it("should only allow successful polls until cost is hit", function()
+			now = 5;
+
+			local a = throttle.create(3, 10);
+			assert.same(a, { balance = 3, max = 3, rate = 0.3, t = 5 });
+
+			assert.is_true(a:poll(1));  -- 3 -> 2
+			assert.same(a, { balance = 2, max = 3, rate = 0.3, t = 5 });
+
+			assert.is_true(a:poll(2));  -- 2 -> 1
+			assert.same(a, { balance = 0, max = 3, rate = 0.3, t = 5 });
+
+			assert.is_false(a:poll(1)); -- MEEP, out of credits!
+			assert.is_false(a:poll(1)); -- MEEP, out of credits!
+			assert.same(a, { balance = 0, max = 3, rate = 0.3, t = 5 });
+		end);
+
+		it("should not allow polls more than the cost", function()
+			now = 0;
+
+			local a = throttle.create(10, 10);
+			assert.same(a, { balance = 10, max = 10, rate = 1, t = 0 });
+
+			assert.is_false(a:poll(11));
+			assert.same(a, { balance = 10, max = 10, rate = 1, t = 0 });
+
+			assert.is_true(a:poll(6));
+			assert.same(a, { balance = 4, max = 10, rate = 1, t = 0 });
+
+			assert.is_false(a:poll(5));
+			assert.same(a, { balance = 4, max = 10, rate = 1, t = 0 });
+
+			-- fractional
+			assert.is_true(a:poll(3.5));
+			assert.same(a, { balance = 0.5, max = 10, rate = 1, t = 0 });
+
+			assert.is_true(a:poll(0.25));
+			assert.same(a, { balance = 0.25, max = 10, rate = 1, t = 0 });
+
+			assert.is_false(a:poll(0.3));
+			assert.same(a, { balance = 0.25, max = 10, rate = 1, t = 0 });
+
+			assert.is_true(a:poll(0.25));
+			assert.same(a, { balance = 0, max = 10, rate = 1, t = 0 });
+
+			assert.is_false(a:poll(0.1));
+			assert.same(a, { balance = 0, max = 10, rate = 1, t = 0 });
+
+			assert.is_true(a:poll(0));
+			assert.same(a, { balance = 0, max = 10, rate = 1, t = 0 });
+		end);
+	end);
+end);