diff --git a/test/library/structures.lua b/test/structures/misc.lua
similarity index 100%
rename from test/library/structures.lua
rename to test/structures/misc.lua
diff --git a/test/structures/unions.lua b/test/structures/unions.lua
new file mode 100644
index 000000000..12de85066
--- /dev/null
+++ b/test/structures/unions.lua
@@ -0,0 +1,19 @@
+local utils = require('utils')
+
+function test.unit_action_fields()
+    dfhack.with_temp_object(df.unit_action:new(), function(action)
+        for k in pairs(action.data) do
+            expect.eq(utils.addressof(action.data.raw_data), utils.addressof(action.data[k]),
+                'address of ' .. k .. ' does not match')
+        end
+    end)
+end
+
+function test.unit_action_type()
+    dfhack.with_temp_object(df.unit_action:new(), function(action)
+        for k, v in ipairs(df.unit_action_type) do
+            expect.true_(action.data[df.unit_action_type.attrs[k].tag])
+            expect.true_(action.data[df.unit_action_type.attrs[v].tag])
+        end
+    end)
+end