Keep mouth crops independent of teeth settings

frontend/test/arthur/flow/measure/interior_test.cljs

@@ -0,0 +1,22 @@
+(ns arthur.flow.measure.interior-test
+  (:require [cljs.test :refer [deftest is]]
+            [arthur.flow.measure.interior :as interior]))
+
+(def ^:private ring
+  [{:x 0.2 :y 0.2} {:x 0.8 :y 0.2}
+   {:x 0.8 :y 0.8} {:x 0.2 :y 0.8}])
+
+(defn- region-size [box cavity-erode]
+  (let [image #js {:data (js/Uint8ClampedArray. (* 4 (:w box) (:h box)))}
+        result (interior/measure
+                {:cavity-erode cavity-erode :tongue-reject 0.1 :blob-grow 0
+                 :top-bias 0 :teeth-verts 8 :min-area 1 :debug? true}
+                box image)]
+    (count (filter pos? (array-seq (get-in result [:debug :region]))))))
+
+(deftest the-crop-is-reusable-while-cavity-erosion-changes-the-measurement
+  (let [box (interior/crop ring [100 100])]
+    (is (= ring (:shape box)))
+    (is (= [20 20 60 60] ((juxt :x :y :w :h) box)))
+    (is (= 3600 (region-size box 0)))
+    (is (= 2304 (region-size box 0.2)))))