Mike Zupperlearn

Branch from DuckDB, course 3 of 3

Testing the Untestable: Workers, WASM, and Shadow DOM

The sequel to the free DuckDB series: a test suite for code jsdom cannot run. Real browsers, real WebAssembly, real workers, deterministic fixtures, fake-timer proofs for a debounced query runner, and end-to-end checks that a database file survives a reload. Seven lessons, $5.

Level
intermediate
Lessons
7
Price
$5

Stops on this branch

7 lessons, about 6 hours.

From DuckDB, Aug 15, 2026

  1. 1Why jsdom Cannot Test This45 min
  2. 2Deterministic Data45 min
  3. 3The Worker Contract Against a Real Engine50 min
  4. 4SQL You Can Trust55 min
  5. 5The Query Runner Under Fake Timers60 min
  6. 6Components, Shadow Roots, and updateComplete50 min
  7. 7End to End, in a Real Browser55 min

Terminus Real browsers, real WebAssembly, real workers.

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