diff --git a/test/Data/Functor/Both/Spec.hs b/test/Data/Functor/Both/Spec.hs
index e1ce51f28..25d998543 100644
--- a/test/Data/Functor/Both/Spec.hs
+++ b/test/Data/Functor/Both/Spec.hs
@@ -1 +1,12 @@
-module Data.Functor.Both.Spec where
+module Data.Functor.Both.Spec (spec) where
+
+import Data.Coalescent
+import Data.Functor.Both
+import Line
+import Test.Hspec
+
+spec :: Spec
+spec = do
+  describe "Coalescent" $ do
+    it "should coalesce when both sides coalesce" $
+      (both (Line [True]) (Line [True]) `coalesce` both (Line [True]) (Line [True]) :: [Both (Line Bool)]) `shouldBe` [both (Line [True, True]) (Line [True, True])]
diff --git a/test/Spec.hs b/test/Spec.hs
index ba2c9bd74..0f6609a7a 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -3,6 +3,7 @@ module Main where
 import qualified AlignmentSpec
 import qualified CorpusSpec
 import qualified Data.Adjoined.Spec
+import qualified Data.Functor.Both.Spec
 import qualified InterpreterSpec
 import qualified OrderedMapSpec
 import qualified PatchOutputSpec
@@ -14,6 +15,7 @@ main = hspec $ parallel $ do
   describe "Alignment" AlignmentSpec.spec
   describe "Corpus" CorpusSpec.spec
   describe "Data.Adjoined" Data.Adjoined.Spec.spec
+  describe "Data.Functor.Both" Data.Functor.Both.Spec.spec
   describe "Interpreter" InterpreterSpec.spec
   describe "OrderedMap" OrderedMapSpec.spec
   describe "PatchOutput" PatchOutputSpec.spec