[spec] test blacklist example

spec/examples/custom-module/blacklist_spec.lua

@@ -0,0 +1,24 @@
+local _M = require 'examples.custom-module.blacklist'
+local apicast = require 'apicast'
+
+describe('blacklist', function()
+  it('returns new module instance', function()
+    local blacklist = _M.new()
+
+    assert.table(blacklist)
+    assert.equal(_M.balancer, blacklist.balancer)
+    assert.equal(_M.init, blacklist.init)
+  end)
+
+  it('has all apicast methods', function()
+    local blacklist = _M.new()
+
+    assert['function'](blacklist.init)
+
+    for _,fun in ipairs{'init_worker', 'rewrite', 'post_action', 'access', 'log'} do
+      assert.equal(apicast[fun], blacklist[fun], fun .. " is not inherited from apicast")
+    end
+
+    assert['function'](blacklist.balancer)
+  end)
+end)