2.21.0

Added

• Assert: Add assert.closeTo(). (@JamesMGreene, @Krinkle) #1735
• Core: Add support for flat preconfig via environment/global variables. (@Krinkle)

Deprecated

• Core: Deprecate QUnit.load() and document migration path at https://qunitjs.com/api/QUnit/load/. #1743
• Core: Deprecate unset testTimeout for tests taking longer than 3 seconds. #1483