.

upickle/test/src/upickle/StructTests.scala

@@ -703,6 +703,24 @@ object StructTests extends TestSuite {
             |}""".stripMargin
         val struct = upickle.default.read[Map[Double, Seq[Map[Double, Int]]]](raw)
 
+        upickle.default.write(struct, indent = 4, sortKeys = true) ==> sorted
+      }
+      test("strings") {
+        // Make sure that when we treat things as Strings, they are sorted
+        // as strings, unlike the above cases where they are treated as numbers
+        val raw = """{"27.5": [{"10.5": 0, "2.5": 1}], "3.5": []}"""
+        val sorted =
+          """{
+            |    "27.5": [
+            |        {
+            |            "10.5": 0,
+            |            "2.5": 1
+            |        }
+            |    ],
+            |    "3.5": []
+            |}""".stripMargin
+        val struct = upickle.default.read[Map[String, Seq[Map[String, Int]]]](raw)
+
         upickle.default.write(struct, indent = 4, sortKeys = true) ==> sorted
       }
     }