[test] WithQuery offline test (with EPO constructor)

test/Test/Offline/JSON.hs

@@ -62,6 +62,7 @@ tests = testGroup "JSON" [
   , testProperty "NodePublishPolicy roundtrips" (jsonEnumRoundtrip (Dict @_ @NodePublishPolicy))
   , testCase "WithQuery frontend compliance" testWithQueryFrontend
   , testCase "WithQuery frontend compliance (PubMed)" testWithQueryFrontendPubMed
+  , testCase "WithQuery frontend compliance (EPO)" testWithQueryFrontendEPO
   , testGroup "Phylo" [
     testProperty "PeriodToNode"  (jsonRoundtrip @PeriodToNodeData)
   , testProperty "GraphData"     (jsonRoundtrip @GraphData)
@@ -88,6 +89,13 @@ testWithQueryFrontendPubMed = do
    Left err -> fail $ "JSON instance will break frontend (PubMed)!: JSON decoding returned: " <> err
    Right _ -> pure ()
 
+
+testWithQueryFrontendEPO :: Assertion
+testWithQueryFrontendEPO = do
+  case  eitherDecode @WithQuery (C8.pack cannedWithQueryPayloadEPO) of
+   Left err -> fail $ "JSON instance will break frontend (EPO)!: JSON decoding returned: " <> err
+   Right _ -> pure ()
+
 -- The aim of this type is to catch regressions in the frontend serialisation; this
 -- is what the frontend currently expects, and therefore if we were to change the JSON
 -- instances, this test would fail, and we will be notified.
@@ -100,6 +108,13 @@ cannedWithQueryPayload = [r| {"query":"Haskell","node_id":138,"lang":"EN","flowL
 cannedWithQueryPayloadPubMed :: String
 cannedWithQueryPayloadPubMed = [r| {"query":"Haskell","node_id":138,"lang":"EN","flowListWith":{"type":"MyListsFirst"},"datafield": { "External": {"db": "PubMed", "api_key": "x"}}} |]
 
+  
+-- The aim of this type is to catch regressions in the frontend serialisation; this
+-- is what the frontend currently expects, and therefore if we were to change the JSON
+-- instances, this test would fail, and we will be notified.
+cannedWithQueryPayloadEPO :: String
+cannedWithQueryPayloadEPO = [r| {"query":"Haskell","node_id":138,"lang":"EN","flowListWith":{"type":"MyListsFirst"},"datafield": { "External": {"db": "EPO", "api_user": "user", "api_token": "token"}}} |]
+
 testParseBpaPhylo :: Assertion
 testParseBpaPhylo = do
   pth      <- getDataFileName "test-data/phylo/bpa_phylo_test.json"