Most mocking libraries do not work in commonTest, and the fix is better anyway
Dynamic proxies need a JVM. What replaces them asserts on outcomes instead of calls.
testing
29 posts
The test that only failed on wasm was measuring the environment
A single-threaded target surfaces every real-clock dependency a JVM run hides.
A Compose UI test in commonTest runs five times and fails on one
The clock, the input source and the available fonts differ per target.
A golden screenshot is a per-platform artifact, whatever the test says
Font rasterisation differs per renderer, so one reference image cannot hold.
runTest skips your delays, which is why the flaky test passed
Virtual time makes a 30-second timeout instant — and makes a real-dispatcher leak invisible.
commonTest runs on every target, which is the point and the cost
One test, five executions. That is how you find platform bugs — and how one flaky test fails five jobs.
163 checks reported green. None of them read the published page.
A verification that asserts on the surface you wrote to will agree with you every time.
Write the failing fixture first or you have written a description
A gate that has never failed might detect nothing. The red fixture is the only evidence it works — and one that trips on two classes localises neither.
It compiles, the test is green, and the screen is a grey box
A structural shell passes an AST scan and a unit test while rendering nothing the mockup specified. Only a rendered check can tell the difference.
The only screenshots worth committing
Golden references are test inputs and belong in version control; run captures are regenerable evidence and do not. Conflating them loses the reference.
A testTag is a contract between the screen and its test
Tests that assert on visible text break on copy edits, which trains people to weaken assertions. A test tag is a deliberate contract that survives rewording.
How do you test a screen whose text is generated?
Snapshot tests die the moment output varies per run. Asserting invariants instead of strings, the vacuous-check trap, and a verdict that means could-not-determine.