util.roles: Return nil if the role has no explicit policy (fixes inheritance)
Previously, if the first inherited role had no opinion, it returned false and
prevented further consultation of other inherited roles.
This bug was found thanks to the implementation of missing test cases
identified through mutation testing.
local hashring = require "util.hashring";
describe("util.hashring", function ()
local sha256 = require "util.hashes".sha256;
local ring = hashring.new(128, sha256);
it("should fail to get a node that does not exist", function ()
assert.is_nil(ring:get_node("foo"))
end);
it("should support adding nodes", function ()
ring:add_node("node1");
end);
it("should return a single node for all keys if only one node exists", function ()
for i = 1, 100 do
assert.is_equal("node1", ring:get_node(tostring(i)))
end
end);
it("should support adding a second node", function ()
ring:add_node("node2");
end);
it("should fail to remove a non-existent node", function ()
assert.is_falsy(ring:remove_node("node3"));
end);
it("should succeed to remove a node", function ()
assert.is_truthy(ring:remove_node("node1"));
end);
it("should return the only node for all keys", function ()
for i = 1, 100 do
assert.is_equal("node2", ring:get_node(tostring(i)))
end
end);
it("should support adding multiple nodes", function ()
ring:add_nodes({ "node1", "node3", "node4", "node5" });
end);
it("should disrupt a minimal number of keys on node removal", function ()
local orig_ring = ring:clone();
local node_tallies = {};
local n = 1000;
for i = 1, n do
local key = tostring(i);
local node = ring:get_node(key);
node_tallies[node] = (node_tallies[node] or 0) + 1;
end
--[[
for node, key_count in pairs(node_tallies) do
print(node, key_count, ("%.2f%%"):format((key_count/n)*100));
end
]]
ring:remove_node("node5");
local disrupted_keys = 0;
for i = 1, n do
local key = tostring(i);
if orig_ring:get_node(key) ~= ring:get_node(key) then
disrupted_keys = disrupted_keys + 1;
end
end
assert.is_equal(node_tallies["node5"], disrupted_keys);
end);
it("should support removing multiple nodes", function ()
ring:remove_nodes({"node2", "node3", "node4", "node5"});
end);
it("should return a single node for all keys if only one node remains", function ()
for i = 1, 100 do
assert.is_equal("node1", ring:get_node(tostring(i)))
end
end);
end);