RUM-1930 Add regression test for Gson toString method

dd-sdk-android-core/src/test/kotlin/com/datadog/android/core/serializer/GsonCompatibilityTests.kt

@@ -0,0 +1,72 @@
+/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2016-Present Datadog, Inc.
+ */
+
+package com.datadog.android.core.serializer
+
+import com.google.gson.JsonObject
+import fr.xgouchet.elmyr.Forge
+import fr.xgouchet.elmyr.junit5.ForgeExtension
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.RepeatedTest
+import org.junit.jupiter.api.extension.ExtendWith
+import org.junit.jupiter.api.extension.Extensions
+
+/**
+ * This class is used to test the compatibility of the Gson serializer with our current `.`
+ * keys in the JSON payloads. This should make sure that Json properties are added into the
+ * `toString` representation in the order they were added in the JSON object.
+ */
+
+@Extensions(ExtendWith(ForgeExtension::class))
+internal class GsonCompatibilityTests {
+
+    @RepeatedTest(5)
+    fun `M add the properties in order in the string W toString()`(forge: Forge) {
+        val propertiesKeysValues = forge.aMap(size = forge.anInt(min = 5, max = 50)) {
+            val key = forge.aList(size = forge.anInt(min = 1, max = 10)) {
+                anAlphabeticalString()
+            }.joinToString(".")
+            val values = listOf<Any>(
+                anInt(),
+                aBool(),
+                aNumericalString(),
+                anHexadecimalString(),
+                anAlphabeticalString()
+            )
+            val value = forge.anElementFrom(values)
+
+            key to value
+        }
+        val expectedJsonRepresentation = buildString {
+            append("{")
+            propertiesKeysValues.entries.forEachIndexed { index, entry ->
+                when (entry.value) {
+                    is Int, is Boolean -> append("\"${entry.key}\":${entry.value}")
+                    else -> append("\"${entry.key}\":\"${entry.value}\"")
+                }
+                if (index < propertiesKeysValues.size - 1) {
+                    append(",")
+                }
+            }
+            append("}")
+        }
+        val jsonObject = JsonObject().apply {
+            propertiesKeysValues.forEach { (key, value) ->
+                when (value) {
+                    is Int -> addProperty(key, value)
+                    is Boolean -> addProperty(key, value)
+                    is String -> addProperty(key, value)
+                }
+            }
+        }
+
+        // When
+        val actualJsonRepresentation = jsonObject.toString()
+
+        // Then
+        assertThat(actualJsonRepresentation).isEqualTo(expectedJsonRepresentation)
+    }
+}