diff --git a/test/mw_engine/drainage_test.clj b/test/mw_engine/drainage_test.clj
new file mode 100644
index 0000000..ba2c95a
--- /dev/null
+++ b/test/mw_engine/drainage_test.clj
@@ -0,0 +1,48 @@
+(ns mw-engine.drainage-test
+  (:require [clojure.test :refer :all]
+            [mw-engine.world :as world]
+            [mw-engine.utils :as utils]
+            [mw-engine.drainage :refer :all]))
+
+(deftest is-hollow-test
+  (testing "detection of hollows"
+           (let [world (utils/set-property
+                   (utils/map-world 
+                     (world/make-world 3 3)
+                     #(merge %2 {:altitude 100}))
+                   1 1 :altitude 90)]
+             (is (is-hollow world (utils/get-cell world 1 1))
+                 "Cell at 1, 1 should be a hollow"))))
+
+(deftest flood-hollow-test
+  (testing "Flooding of a single specified cell"
+             (let [world (utils/set-property
+                   (utils/map-world 
+                     (world/make-world 3 3)
+                     #(merge %2 {:altitude 100}))
+                   1 1 :altitude 90)
+                   cell (flood-hollow world (utils/get-cell world 1 1))]
+               (is (= (:state cell) :water)
+                   "State should be water")
+               (is (= (:altitude cell) 100)
+                   "Altitude should be 100"))))
+               
+(deftest flood-hollows-test
+  (testing "Flooding of hollows"
+           (let [world (utils/set-property
+                   (utils/map-world 
+                     (world/make-world 3 3)
+                     #(merge %2 {:altitude 100}))
+                   1 1 :altitude 90)
+                 w2 (flood-hollows world)]
+             (is (= (:state (utils/get-cell world 1 1)) :new)
+                 "State of cell in original world should still be :new")
+             (is (= (:state (utils/get-cell w2 1 1)) :water)
+                 "State of cell in processed world should still be :water")
+             (is (= (:altitude (utils/get-cell w2 1 1)) 100)
+                 "Altitude of cell in processed world should still be 100"))))
+             
+                                  
+
+  
+  
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