secondlife/viewer-issues#72: Add test plan

doc/testplans/material_preview.md

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+# Material Preview
+
+## Overview
+
+Material preview is a UI feature which displays a lit spherical preview of a PBR material. It can be found in the following UIs:
+
+- The material picker swatch
+    - In the build floater, in the Texture tab, when applying a PBR material
+    - (If the feature is enabled) In the Region/Estate floater, in the Terrain tab, when applying PBR materials to terrain
+- In the floater to select a material from inventory, which can be opened by clicking the material picker swatch
+
+## Known Issues
+
+These are known issues that the current implementation of this feature does not address:
+
+- Material swatch preview is a preview of the base material ID only, and ignores other properties on the prim face like material overrides
+- Alpha mask previews as alpha blend
+- Double-sided previews as single-sided
+- Material swatch preview inherits some of its lighting from the current environment, and reflections from the default reflection probe
+
+## General Regression Testing
+
+- Check that the material preview swatch looks OK with different materials selected
+- Check that the material preview swatch runs reasonably well on different systems, especially when the select material from inventory floater is also open
+    - In particular: AMD, MacOS, minimum spec machines
+- Watch out for regressions in rendering caused by opening a floater with a material preview swatch
+
+## Bug Fixes
+
+### Disappearing Objects Fix Test
+
+This test is recommended for verifying that secondlife/viewer-issues#72 is fixed.
+
+#### Symptoms
+
+The following types of objects could randomly disappear until relog in the main view when the bug occured:
+
+- Objects
+- Water level in current region
+- Adjacent region/void water
+
+Note: Disappearing objects in reflections have a different root cause and are not covered by the fix.
+
+#### Bug Reproduction Steps
+
+Verify the disappearing objects bug does not reproduce, given the following steps:
+
+- Runtime prerequisites: Material preview swatch is enabled ("UIPreviewMaterial") by visiting a test region with the feature enabled, or by manually enabling "UIPreviewMaterial" in the advanced settings for the current session
+- Region prerequisites: Unknown, but a region with lots of stuff in it (like Rumpus Room 2048 on Aditi) seems to increase repro rate
+- Right click an object and select, "Edit item"
+- Go to texture tab, select PBR Metallic Roughness from dropdown, and click the button to select material from inventory
+- Ensure "Apply now" is checked in the inventory selection floater
+- Alternate between different materials from the inventory selection floater
+- Look around the world and check for permanently disappeared objects.
+
+### Dynamic Exposure Influence Fix Test
+
+This test is recommended for verifying that secondlife/viewer-issues#72 is fixed.
+
+#### Symptoms
+
+Dynamic exposure in the world could be influenced by the material preview being displayed. If a material preview was being generated in a given frame, then, depending on the current environment, the user would observe an unpleasant flashing effect in the environment:
+
+- The world view could suddenly get darker and then fade back to normal exposure levels
+- The world view could suddenly get brighter and then fade back to normal exposure levels
+
+#### Bug Reproduction Steps
+
+Verify the dynamic exposure influence bug does not reproduce. Test using a few environment presets such as Default Midday, Sunset, and Midnight.
+
+- Right click an object and select, "Edit item"
+- Go to texture tab, select PBR Metallic Roughness from dropdown, and click the button to select material from inventory
+- Alternate between different materials from the inventory selection floater
+
+#### Regression Testing
+
+Dynamic exposure in the world should continue to work correctly. In particular:
+
+- Exposure should fade gradually from high exposure to low exposure and back as needed
+- Exposure should decrease in brighter environments
+- Exposure should increase in darker environments