Write a proper check

flake.nix

@@ -93,9 +93,18 @@
         ];
       };
     in {
-      inherit sqlite-example-exts-static;
-      sqlite-with-static-ext = sqlite-with-static-exts.sqlite;
-      sqlite-cli-with-static-ext = sqlite-with-static-exts.sqlite-cli;
+      checkExts = pkgs.runCommand "test-sqlite-with-static-exts" {
+        nativeBuildInputs = [ sqlite-with-static-exts.sqlite-cli ];
+
+        passthru = {
+          inherit sqlite-example-exts-static;
+          inherit sqlite-with-static-exts;
+        };
+      } ''
+        mkdir -p "$out"
+        sqlite3 :memory: <<<"SELECT myadd(1, 2), mysub(5, 3), mymult(4, 6);" | tee "$out/test.log"
+        grep -q -F "3|2|24" "$out/test.log" || (echo "Unexpected output from sqlite3 with static extensions" && exit 1)
+       '';
     });
   };
 }