Adding some comments based on study of the test framework

The original developer created an interesting testing approach but I felt it needed some clues for how it works.

Author: SkowronskiAndrew

TestCommon/TestFixtures.cs

@@ -4,6 +4,9 @@
 
 namespace UnityDataTools.TestCommon;
 
+// Base class that facilitates iterating through sub-sub-folders
+// inside the Data location.  E.g. GetContexts("AssetBundles")
+// finds "TestCommon/Data/AssetBundles/2019.4.0f1", "TestCommon/Data/AssetBundles/2020.3.0f1" etc.
 public class BaseTestFixture
 {
     protected Context Context { get; }
@@ -15,6 +18,8 @@ public BaseTestFixture(Context context)
         Context = context;
     }
 
+    // Tests that have files that record the expected results for each version
+    // of Unity can override this method to regenerate those expected results.
     protected virtual void OnLoadExpectedData(Context context)
     {
     }
@@ -23,6 +28,9 @@ protected virtual void OnLoadExpectedData(Context context)
     public void LoadExpectedData()
     {
         OnLoadExpectedData(Context);
+
+        // Load json file with the expected results for a test based on
+        // folder structure convention (e.g. ExpectedData/<UnityVersion>/ExpectedVersions.json)
         Context.ExpectedData.Load(Context.ExpectedDataFolder);
     }
 
@@ -47,6 +55,9 @@ protected static IEnumerable<Context> GetContexts(string dataFolder)
     }
 }
 
+// Test fixture that repeats the tests for each folder inside TestCommon/Data/AssetBundles.
+// Each sub-folder is expected to have results of an AssetBundle build repeated with a
+// different version of Unity.
 [TestFixtureSource(typeof(AssetBundleTestFixture), nameof(GetContexts))]
 public class AssetBundleTestFixture : BaseTestFixture
 {

UnityDataTool.Tests/ExpectedDataGenerator.cs

@@ -5,6 +5,10 @@
 
 namespace UnityDataTools.UnityDataTool.Tests;
 
+// Collect and record the current output returned by the same UnityDataTool commands
+// that the tests will run.  Once saved these become the reference data, and if the output
+// changes the tests will fail.  So this can be repeated if there is an "expected" change
+// in the output.
 public static class ExpectedDataGenerator
 {
     public static void Generate(Context context)
@@ -71,6 +75,9 @@ public static void Generate(Context context)
         var csprojFolder = Directory.GetParent(context.TestDataFolder).Parent.Parent.Parent.FullName;
         var outputFolder = Path.Combine(csprojFolder, "ExpectedData", context.UnityDataVersion);
 
+        expectedData.Save(outputFolder);
+
+        // Also take a snapshot of the output of running "dump" commands on the test file "assetbundle"
         Directory.CreateDirectory(outputFolder);
 
         var dumpPath = Path.Combine(outputFolder, "dump");
@@ -80,7 +87,5 @@ public static void Generate(Context context)
         dumpPath = Path.Combine(outputFolder, "dump-s");
         Directory.CreateDirectory(dumpPath);
         Program.Main(new string[] { "dump", Path.Combine(context.UnityDataFolder, "assetbundle"), "-o", dumpPath, "-s" });
-
-        expectedData.Save(outputFolder);
     }
 }