Snapshot tests are a very useful tool whenever you want to make sure your UI does not change unexpectedly.
A typical snapshot test case renders a UI component, takes a snapshot, then compares it to a reference snapshot file stored alongside the test. The test will fail if the two snapshots do not match: either the change is unexpected, or the reference snapshot needs to be updated to the new version of the UI component.
Source: jestjs.io
Came across this in a viem test using toMatchInlineSnapshot().
test("gasPrice", async () => {
expect(
await signTransaction(walletClient, {
account: privateKeyToAccount(sourceAccount.privateKey),
...baseLegacy,
gasPrice: parseGwei("20"),
})
).toMatchInlineSnapshot(
'"0xf8518203118504a817c800825208808080259f672886c0db7d3a2710b5bb8b64fd516ff4fede94f34e76b22f451e5ff92ecfa0627283bbafb0600cd997c8dbfa6f4173c5376e2c4c57967541e171fb110b6d64"'
);
});See comment in code review.