diff --git a/marlowe-runtime/test/Language/Marlowe/Runtime/Transaction/ApiSpec.hs b/marlowe-runtime/test/Language/Marlowe/Runtime/Transaction/ApiSpec.hs
index f2886c1257..d6a95d978c 100644
--- a/marlowe-runtime/test/Language/Marlowe/Runtime/Transaction/ApiSpec.hs
+++ b/marlowe-runtime/test/Language/Marlowe/Runtime/Transaction/ApiSpec.hs
@@ -14,12 +14,14 @@ import qualified Data.Aeson as Aeson
 import qualified Data.Aeson.Key as Aeson.Key
 import qualified Data.Aeson.KeyMap as Aeson.KeyMap
 import Data.Coerce (coerce)
+import Data.Foldable (find)
 import Data.Map (Map)
 import qualified Data.Map as Map
 import Data.Maybe (maybeToList)
 import qualified Data.Maybe as Maybe
 import Data.String (fromString)
 import Data.Text (Text)
+import qualified Data.Text as Text
 import qualified Data.Text.Encoding as Text.Encoding
 import qualified Data.Text.Encoding.Base16 as Base16
 import qualified Data.Vector as Vector
@@ -105,12 +107,16 @@ validityProp = Gen.checkCoverage $
 
 cip25MetadataFileDetailsGenSoundnessProp :: Gen.Property
 cip25MetadataFileDetailsGenSoundnessProp = Gen.checkCoverage $
-  Gen.forAll cip25MetadataFileDetailsJSONRelationGen \(cip25MetadataFileDetails, json) ->
-    Gen.cover 1.0 (null cip25MetadataFileDetails) "no file details" $
-    Gen.cover 80.0 (not $ null cip25MetadataFileDetails) "some file details" do
+  Gen.forAll cip25MetadataFileDetailsJSONRelationGen \(fds, json) ->
+    Gen.cover 25.0 (Maybe.isJust $ find (\CIP25MetadataFileDetails{..} -> Text.null name) fds) "some file details has empty name" $
+    Gen.cover 25.0 (Maybe.isJust $ find (\CIP25MetadataFileDetails{..} -> not $ Text.null name) fds) "some file details has name" $
+    Gen.cover 25.0 (Maybe.isJust $ find (\CIP25MetadataFileDetails{..} -> Text.null mediaType) fds) "some file details has empty mediaType" $
+    Gen.cover 25.0 (Maybe.isJust $ find (\CIP25MetadataFileDetails{..} -> not $ Text.null mediaType) fds) "some file details has mediaType" $
+    Gen.cover 1.0 (null fds) "no file details" $
+    Gen.cover 80.0 (not $ null fds) "some file details" do
     let document = Aeson.encode json
-    Aeson.encode cip25MetadataFileDetails `shouldBe` document
-    -- Aeson.decode document `shouldBe` Just cip25MetadataFileDetails
+    Aeson.encode fds `shouldBe` document
+    -- Aeson.decode document `shouldBe` Just fds
 
 cip25MetadataFileDetailsJSONRelationGen :: Gen ([CIP25MetadataFileDetails], Aeson.Value)
 cip25MetadataFileDetailsJSONRelationGen = do