no-zero-vitest-slow-test-threshold

Disallow test.slowTestThreshold: 0 in Vitest configuration.

Rule catalog ID: R021

Targeted pattern scope

• vitest.config.*
• vitest.workspace.*
• vite.config.* when a Vitest test block is used
• root and inline project test.slowTestThreshold

What this rule reports

This rule reports explicit test.slowTestThreshold: 0 assignments.

Why this rule exists

slowTestThreshold controls when Vitest reports slow tests. Setting it to 0 disables practical slow-test signal and makes it harder to detect performance regressions in the suite.

This repository focuses on configuration quality, so preventing disabled slow-test reporting is a useful Vitest-specific guardrail.

❌ Incorrect

import { defineConfig } from "vitest/config";

export default defineConfig({
    test: {
        slowTestThreshold: 0,
    },
});

✅ Correct

import { defineConfig } from "vitest/config";

export default defineConfig({
    test: {
        slowTestThreshold: 300,
    },
});

Behavior and migration notes

• this rule only reports explicit zero-valued thresholds
• it does not require setting slowTestThreshold when omitted
• tune the threshold to fit your environment (e.g. 300–1000 ms) rather than disabling the signal entirely

ESLint flat config example

import vite from "@typpi/eslint-plugin-vite";

export default [vite.configs.strict, vite.configs.vitest];

When not to use it

Disable this rule only if your project intentionally removes slow-test reporting from committed Vitest configuration.

Package documentation

• Vitest config reference
• Vitest slowTestThreshold option

Further reading

• no-zero-vitest-timeout
• no-disabled-vitest-isolation