feat!: set 'v8' as default coverage.provider

docs/config/index.md

@@ -664,7 +664,7 @@ If you are using coverage options with dot notation, don't forget to specify `--
 #### coverage.provider
 
 - **Type:** `'c8' | 'v8' | 'istanbul' | 'custom'`
-- **Default:** `'c8'`
+- **Default:** `'v8'`
 - **CLI:** `--coverage.provider=<provider>`
 
 Use `provider` to select the tool for coverage collection.

packages/vitest/src/defaults.ts

@@ -27,7 +27,7 @@ const defaultCoverageExcludes = [
 
 // These are the generic defaults for coverage. Providers may also set some provider specific defaults.
 export const coverageConfigDefaults: ResolvedCoverageOptions = {
-  provider: 'c8',
+  provider: 'v8',
   enabled: false,
   clean: true,
   cleanOnRerun: true,

packages/vitest/src/node/cli-api.ts

@@ -59,11 +59,21 @@ export async function startVitest(
   const ctx = await createVitest(mode, options, viteOverrides)
 
   if (mode === 'test' && ctx.config.coverage.enabled) {
-    const provider = ctx.config.coverage.provider || 'c8'
+    const provider = ctx.config.coverage.provider || 'v8'
     const requiredPackages = CoverageProviderMap[provider]
 
     if (requiredPackages) {
-      if (!await ensurePackageInstalled(requiredPackages, root)) {
+      // Remove this message once support for @vitest/coverage-c8 has been removed completely
+      const defaultProviderInfo = 'Default coverage provider has changed from "c8" to "v8". '
+        + 'New package is required to be installed. '
+        + 'To use the old deprecated coverage provider use "--coverage.provider c8" option.\n'
+        + 'See https://github.com/vitest-dev/vitest/pull/3339 for more information.\n\n'
+
+      const isUsingDefaultProvider
+        = ctx.server.config.test?.coverage?.provider === undefined
+        && options.coverage?.provider === undefined
+
+      if (!await ensurePackageInstalled(requiredPackages, root, isUsingDefaultProvider ? defaultProviderInfo : undefined)) {
         process.exitCode = 1
         return ctx
       }

packages/vitest/src/node/pkg.ts

@@ -9,12 +9,16 @@ const __dirname = url.fileURLToPath(new URL('.', import.meta.url))
 export async function ensurePackageInstalled(
   dependency: string,
   root: string,
+  errorMessage?: string,
 ) {
   if (isPackageExists(dependency, { paths: [root, __dirname] }))
     return true
 
   const promptInstall = !isCI && process.stdout.isTTY
 
+  if (errorMessage)
+    process.stderr.write(c.red(errorMessage))
+
   process.stderr.write(c.red(`${c.inverse(c.red(' MISSING DEP '))} Can not find dependency '${dependency}'\n\n`))
 
   if (!promptInstall)

test/config/test/failures.test.ts

@@ -40,13 +40,13 @@ test('inspect-brk cannot be used with threads', async () => {
 })
 
 test('c8 coverage provider cannot be used with browser', async () => {
-  const { error } = await runVitest('run', ['--coverage.enabled', '--browser'])
+  const { error } = await runVitest('run', ['--coverage.enabled', '--coverage.provider', 'c8', '--browser'])
 
   expect(error).toMatch('Error: @vitest/coverage-c8 does not work with --browser. Use @vitest/coverage-istanbul instead')
 })
 
 test('v8 coverage provider cannot be used with browser', async () => {
-  const { error } = await runVitest('run', ['--coverage.enabled', '--coverage.provider', 'v8', '--browser'])
+  const { error } = await runVitest('run', ['--coverage.enabled', '--browser'])
 
   expect(error).toMatch('Error: @vitest/coverage-v8 does not work with --browser. Use @vitest/coverage-istanbul instead')
 })