prosody/tests/test_util_cache.lua

function new(new)
	local c = new(5);

	local function expect_kv(key, value, actual_key, actual_value)
		assert_equal(key, actual_key, "key incorrect");
		assert_equal(value, actual_value, "value incorrect");
	end

	expect_kv(nil, nil, c:head());
	expect_kv(nil, nil, c:tail());

	assert_equal(c:count(), 0);

	c:set("one", 1)
	assert_equal(c:count(), 1);
	expect_kv("one", 1, c:head());
	expect_kv("one", 1, c:tail());

	c:set("two", 2)
	expect_kv("two", 2, c:head());
	expect_kv("one", 1, c:tail());

	c:set("three", 3)
	expect_kv("three", 3, c:head());
	expect_kv("one", 1, c:tail());

	c:set("four", 4)
	c:set("five", 5);
	assert_equal(c:count(), 5);
	expect_kv("five", 5, c:head());
	expect_kv("one", 1, c:tail());

	c:set("foo", nil);
	assert_equal(c:count(), 5);
	expect_kv("five", 5, c:head());
	expect_kv("one", 1, c:tail());

	assert_equal(c:get("one"), 1);
	expect_kv("five", 5, c:head());
	expect_kv("one", 1, c:tail());

	assert_equal(c:get("two"), 2);
	assert_equal(c:get("three"), 3);
	assert_equal(c:get("four"), 4);
	assert_equal(c:get("five"), 5);

	assert_equal(c:get("foo"), nil);
	assert_equal(c:get("bar"), nil);

	c:set("six", 6);
	assert_equal(c:count(), 5);
	expect_kv("six", 6, c:head());
	expect_kv("two", 2, c:tail());

	assert_equal(c:get("one"), nil);
	assert_equal(c:get("two"), 2);
	assert_equal(c:get("three"), 3);
	assert_equal(c:get("four"), 4);
	assert_equal(c:get("five"), 5);
	assert_equal(c:get("six"), 6);

	c:set("three", nil);
	assert_equal(c:count(), 4);

	assert_equal(c:get("one"), nil);
	assert_equal(c:get("two"), 2);
	assert_equal(c:get("three"), nil);
	assert_equal(c:get("four"), 4);
	assert_equal(c:get("five"), 5);
	assert_equal(c:get("six"), 6);

	c:set("seven", 7);
	assert_equal(c:count(), 5);

	assert_equal(c:get("one"), nil);
	assert_equal(c:get("two"), 2);
	assert_equal(c:get("three"), nil);
	assert_equal(c:get("four"), 4);
	assert_equal(c:get("five"), 5);
	assert_equal(c:get("six"), 6);
	assert_equal(c:get("seven"), 7);

	c:set("eight", 8);
	assert_equal(c:count(), 5);

	assert_equal(c:get("one"), nil);
	assert_equal(c:get("two"), nil);
	assert_equal(c:get("three"), nil);
	assert_equal(c:get("four"), 4);
	assert_equal(c:get("five"), 5);
	assert_equal(c:get("six"), 6);
	assert_equal(c:get("seven"), 7);
	assert_equal(c:get("eight"), 8);

	c:set("four", 4);
	assert_equal(c:count(), 5);

	assert_equal(c:get("one"), nil);
	assert_equal(c:get("two"), nil);
	assert_equal(c:get("three"), nil);
	assert_equal(c:get("four"), 4);
	assert_equal(c:get("five"), 5);
	assert_equal(c:get("six"), 6);
	assert_equal(c:get("seven"), 7);
	assert_equal(c:get("eight"), 8);

	c:set("nine", 9);
	assert_equal(c:count(), 5);

	assert_equal(c:get("one"), nil);
	assert_equal(c:get("two"), nil);
	assert_equal(c:get("three"), nil);
	assert_equal(c:get("four"), 4);
	assert_equal(c:get("five"), nil);
	assert_equal(c:get("six"), 6);
	assert_equal(c:get("seven"), 7);
	assert_equal(c:get("eight"), 8);
	assert_equal(c:get("nine"), 9);

	do
		local keys = { "nine", "four", "eight", "seven", "six" };
		local values = { 9, 4, 8, 7, 6 };
		local i = 0;
		for k, v in c:items() do
			i = i + 1;
			assert_equal(k, keys[i]);
			assert_equal(v, values[i]);
		end
		assert_equal(i, 5);

		c:set("four", "2+2");
		assert_equal(c:count(), 5);

		assert_equal(c:get("one"), nil);
		assert_equal(c:get("two"), nil);
		assert_equal(c:get("three"), nil);
		assert_equal(c:get("four"), "2+2");
		assert_equal(c:get("five"), nil);
		assert_equal(c:get("six"), 6);
		assert_equal(c:get("seven"), 7);
		assert_equal(c:get("eight"), 8);
		assert_equal(c:get("nine"), 9);
	end

	do
		local keys = { "four", "nine", "eight", "seven", "six" };
		local values = { "2+2", 9, 8, 7, 6 };
		local i = 0;
		for k, v in c:items() do
			i = i + 1;
			assert_equal(k, keys[i]);
			assert_equal(v, values[i]);
		end
		assert_equal(i, 5);

		c:set("foo", nil);
		assert_equal(c:count(), 5);

		assert_equal(c:get("one"), nil);
		assert_equal(c:get("two"), nil);
		assert_equal(c:get("three"), nil);
		assert_equal(c:get("four"), "2+2");
		assert_equal(c:get("five"), nil);
		assert_equal(c:get("six"), 6);
		assert_equal(c:get("seven"), 7);
		assert_equal(c:get("eight"), 8);
		assert_equal(c:get("nine"), 9);
	end

	do
		local keys = { "four", "nine", "eight", "seven", "six" };
		local values = { "2+2", 9, 8, 7, 6 };
		local i = 0;
		for k, v in c:items() do
			i = i + 1;
			assert_equal(k, keys[i]);
			assert_equal(v, values[i]);
		end
		assert_equal(i, 5);

		c:set("four", nil);

		assert_equal(c:get("one"), nil);
		assert_equal(c:get("two"), nil);
		assert_equal(c:get("three"), nil);
		assert_equal(c:get("four"), nil);
		assert_equal(c:get("five"), nil);
		assert_equal(c:get("six"), 6);
		assert_equal(c:get("seven"), 7);
		assert_equal(c:get("eight"), 8);
		assert_equal(c:get("nine"), 9);
	end

	do
		local keys = { "nine", "eight", "seven", "six" };
		local values = { 9, 8, 7, 6 };
		local i = 0;
		for k, v in c:items() do
			i = i + 1;
			assert_equal(k, keys[i]);
			assert_equal(v, values[i]);
		end
		assert_equal(i, 4);
	end

	do
		local evicted_key, evicted_value;
		local c2 = new(3, function (_key, _value)
			evicted_key, evicted_value = _key, _value;
		end);
		local function set(k, v, should_evict_key, should_evict_value)
			evicted_key, evicted_value = nil, nil;
			c2:set(k, v);
			assert_equal(evicted_key, should_evict_key);
			assert_equal(evicted_value, should_evict_value);
		end
		set("a", 1)
		set("a", 1)
		set("a", 1)
		set("a", 1)
		set("a", 1)

		set("b", 2)
		set("c", 3)
		set("b", 2)
		set("d", 4, "a", 1)
		set("e", 5, "c", 3)
	end

	do
		local evicted_key, evicted_value;
		local c3 = new(1, function (_key, _value)
			evicted_key, evicted_value = _key, _value;
			if _key == "a" then
				-- Sanity check for what we're evicting
				assert_equal(_key, "a");
				assert_equal(_value, 1);
				-- We're going to block eviction of this key/value, so set to nil...
				evicted_key, evicted_value = nil, nil;
				-- Returning false to block eviction
				return false
			end
		end);
		local function set(k, v, should_evict_key, should_evict_value)
			evicted_key, evicted_value = nil, nil;
			local ret = c3:set(k, v);
			assert_equal(evicted_key, should_evict_key);
			assert_equal(evicted_value, should_evict_value);
			return ret;
		end
		set("a", 1)
		set("a", 1)
		set("a", 1)
		set("a", 1)
		set("a", 1)

		-- Our on_evict prevents "a" from being evicted, causing this to fail...
		assert_equal(set("b", 2), false, "Failed to prevent eviction, or signal result");

		expect_kv("a", 1, c3:head());
		expect_kv("a", 1, c3:tail());

		-- Check the final state is what we expect
		assert_equal(c3:get("a"), 1);
		assert_equal(c3:get("b"), nil);
		assert_equal(c3:count(), 1);
	end


	local c4 = new(3, false);

	assert_equal(c4:set("a", 1), true);
	assert_equal(c4:set("a", 1), true);
	assert_equal(c4:set("a", 1), true);
	assert_equal(c4:set("a", 1), true);
	assert_equal(c4:set("b", 2), true);
	assert_equal(c4:set("c", 3), true);
	assert_equal(c4:set("d", 4), false);
	assert_equal(c4:set("d", 4), false);
	assert_equal(c4:set("d", 4), false);

	expect_kv("c", 3, c4:head());
	expect_kv("a", 1, c4:tail());

	local c5 = new(3, function (k, v)
		if k == "a" then
			return nil;
		elseif k == "b" then
			return true;
		end
		return false;
	end);

	assert_equal(c5:set("a", 1), true);
	assert_equal(c5:set("a", 1), true);
	assert_equal(c5:set("a", 1), true);
	assert_equal(c5:set("a", 1), true);
	assert_equal(c5:set("b", 2), true);
	assert_equal(c5:set("c", 3), true);
	assert_equal(c5:set("d", 4), true); -- "a" evicted (cb returned nil)
	assert_equal(c5:set("d", 4), true); -- nop
	assert_equal(c5:set("d", 4), true); -- nop
	assert_equal(c5:set("e", 5), true); -- "b" evicted (cb returned true)
	assert_equal(c5:set("f", 6), false); -- "c" won't evict (cb returned false)

	expect_kv("e", 5, c5:head());
	expect_kv("c", 3, c5:tail());

end