test(audience-sdk): centralise paired JSON round-trip fixtures

JsonTests and JsonReaderTests both used the same literals to verify
round-trip behaviour: each input dictionary in JsonTests had a
matching encoded form in JsonReaderTests, and vice versa. The
single string pair (key / hello), the all-escapes string (val /
"say \"hi\"\nback\\slash\ttab"), and the nested object (outer /
inner / value) appeared duplicated in both files.

Adds JsonRoundTripFixtures with the raw key, raw value, and
exact-encoded form for each of the three pairs. Migrates six
references across the two files.

Renaming any fixture (e.g. swapping "hello" for "world") now needs
one edit and both tests stay coherent.

Per the user's "everything random goes in a constant" stance.

Follow-up to SDK-272 (centralisation of duplicated literals).

Author: ImmutableJeffrey

src/Packages/Audience/Tests/Runtime/Utility/JsonReaderTests.cs

@@ -16,15 +16,15 @@ public void EmptyObject()
         [Test]
         public void StringValue()
         {
-            var result = JsonReader.DeserializeObject("{\"key\":\"hello\"}");
-            Assert.AreEqual("hello", result["key"]);
+            var result = JsonReader.DeserializeObject(JsonRoundTripFixtures.KeyHelloEncoded);
+            Assert.AreEqual(JsonRoundTripFixtures.HelloValue, result[JsonRoundTripFixtures.KeyName]);
         }
 
         [Test]
         public void StringWithEscapes()
         {
-            var result = JsonReader.DeserializeObject("{\"val\":\"say \\\"hi\\\"\\nback\\\\slash\\ttab\"}");
-            Assert.AreEqual("say \"hi\"\nback\\slash\ttab", result["val"]);
+            var result = JsonReader.DeserializeObject(JsonRoundTripFixtures.ValEscapeRichEncoded);
+            Assert.AreEqual(JsonRoundTripFixtures.EscapeRichString, result[JsonRoundTripFixtures.ValName]);
         }
 
         [Test]
@@ -47,9 +47,9 @@ public void BoolAndNull()
         [Test]
         public void NestedObject()
         {
-            var result = JsonReader.DeserializeObject("{\"outer\":{\"inner\":\"value\"}}");
-            var inner = (Dictionary<string, object>)result["outer"];
-            Assert.AreEqual("value", inner["inner"]);
+            var result = JsonReader.DeserializeObject(JsonRoundTripFixtures.OuterInnerEncoded);
+            var inner = (Dictionary<string, object>)result[JsonRoundTripFixtures.OuterKey];
+            Assert.AreEqual(JsonRoundTripFixtures.InnerValue, inner[JsonRoundTripFixtures.InnerKey]);
         }
 
         [Test]

src/Packages/Audience/Tests/Runtime/Utility/JsonRoundTripFixtures.cs

@@ -0,0 +1,24 @@
+namespace Immutable.Audience.Tests
+{
+    // Paired serialise/deserialise fixtures shared between JsonTests and JsonReaderTests.
+    // Each pair pins the round-trip guarantee.
+    internal static class JsonRoundTripFixtures
+    {
+        // Single string key / value pair.
+        internal const string KeyName = "key";
+        internal const string HelloValue = "hello";
+        internal const string KeyHelloEncoded = "{\"key\":\"hello\"}";
+
+        // String containing every escape sequence the codec handles
+        // (escaped quote, newline, backslash, tab).
+        internal const string ValName = "val";
+        internal const string EscapeRichString = "say \"hi\"\nback\\slash\ttab";
+        internal const string ValEscapeRichEncoded = "{\"val\":\"say \\\"hi\\\"\\nback\\\\slash\\ttab\"}";
+
+        // Nested object.
+        internal const string OuterKey = "outer";
+        internal const string InnerKey = "inner";
+        internal const string InnerValue = "value";
+        internal const string OuterInnerEncoded = "{\"outer\":{\"inner\":\"value\"}}";
+    }
+}

src/Packages/Audience/Tests/Runtime/Utility/JsonRoundTripFixtures.cs.meta

@@ -18,24 +18,24 @@ public void Serialize_EmptyDict_ReturnsEmptyObject()
         [Test]
         public void Serialize_StringValue_ReturnsQuotedString()
         {
-            var data = new Dictionary<string, object> { { "key", "hello" } };
+            var data = new Dictionary<string, object> { { JsonRoundTripFixtures.KeyName, JsonRoundTripFixtures.HelloValue } };
 
             var result = Json.Serialize(data);
 
-            Assert.AreEqual("{\"key\":\"hello\"}", result);
+            Assert.AreEqual(JsonRoundTripFixtures.KeyHelloEncoded, result);
         }
 
         [Test]
         public void Serialize_StringWithSpecialChars_EscapesCorrectly()
         {
             var data = new Dictionary<string, object>
             {
-                { "val", "say \"hi\"\nback\\slash\ttab" }
+                { JsonRoundTripFixtures.ValName, JsonRoundTripFixtures.EscapeRichString }
             };
 
             var result = Json.Serialize(data);
 
-            Assert.AreEqual("{\"val\":\"say \\\"hi\\\"\\nback\\\\slash\\ttab\"}", result);
+            Assert.AreEqual(JsonRoundTripFixtures.ValEscapeRichEncoded, result);
         }
 
         [Test]
@@ -84,14 +84,14 @@ public void Serialize_NestedDict_ReturnsNestedObject()
             var data = new Dictionary<string, object>
             {
                 {
-                    "outer", new Dictionary<string, object>
+                    JsonRoundTripFixtures.OuterKey, new Dictionary<string, object>
                     {
-                        { "inner", "value" }
+                        { JsonRoundTripFixtures.InnerKey, JsonRoundTripFixtures.InnerValue }
                     }
                 }
             };
 
-            Assert.AreEqual("{\"outer\":{\"inner\":\"value\"}}", Json.Serialize(data));
+            Assert.AreEqual(JsonRoundTripFixtures.OuterInnerEncoded, Json.Serialize(data));
         }
 
         [Test]