Total test duration is wrong in `--merge-reports`

[kettanaito]

Describe the bug

When merging reports from a sharded test run, the merged report prints an incorrect total duration:

npx vitest run --merge-reports

 ✓ src/one.test.ts (500 tests) 268ms
 ✓ src/two.test.ts (500 tests) 266ms

 Test Files  2 passed (2)
      Tests  1000 passed (1000)
   Start at  11:48:26
   Duration  6ms (transform 0ms, setup 0ms, collect 25ms, tests 534ms, environment 0ms, prepare 86ms)
             ^^^

The tests have clearly taken more time than 6ms to run. It is also apparent from the detailed timings in parenthesis.

It seems that the total time here is of the --merge-report command itself, not the total time of the merged tests, which can be misleading.

Reproduction

You can reproduce this issue by following the Sharing recipe from the Vitest docs. No additional changes were made.

System Info

—

Used Package Manager

npm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[AriPerkkio]

I don't think the total duration is saved anywhere. It's reporter specifid metric only:

vitest/packages/vitest/src/node/reporters/base.ts

Lines 23 to 25 in 4128665

	export abstract class BaseReporter implements Reporter {
	start = 0
	end = 0

vitest/packages/vitest/src/node/reporters/base.ts

Lines 484 to 509 in 4128665

	const collectTime = sum(files, file => file.collectDuration)
	const testsTime = sum(files, file => file.result?.duration)
	const setupTime = sum(files, file => file.setupDuration)
	if (this.watchFilters) {
	this.log(padSummaryTitle('Duration'), formatTime(collectTime + testsTime + setupTime))
	}
	else {
	const executionTime = this.end - this.start
	const environmentTime = sum(files, file => file.environmentLoad)
	const prepareTime = sum(files, file => file.prepareDuration)
	const transformTime = sum(this.ctx.projects, project => project.vitenode.getTotalDuration())
	const typecheck = sum(this.ctx.projects, project => project.typechecker?.getResult().time)
	const timers = [
	`transform ${formatTime(transformTime)}`,
	`setup ${formatTime(setupTime)}`,
	`collect ${formatTime(collectTime)}`,
	`tests ${formatTime(testsTime)}`,
	`environment ${formatTime(environmentTime)}`,
	`prepare ${formatTime(prepareTime)}`,
	typecheck && `typecheck ${formatTime(typecheck)}`,
	].filter(Boolean).join(', ')
	this.log(padSummaryTitle('Duration'), formatTime(executionTime) + c.dim(` (${timers})`))
	}

We should probably add similar to blob reporter and use it here:

vitest/packages/vitest/src/node/reporters/blob.ts

Lines 59 to 65 in 4128665

	const report = stringify([
	this.ctx.version,
	files,
	errors,
	modules,
	coverage,
	] satisfies MergeReport)

[AriPerkkio]

We should probably report total time that's sum of run time of all test shards, and each test shard's time separately:

 Test Files  2 passed (2)
      Tests  1000 passed (1000)
   Start at  11:48:26
-   Duration  6ms   (transform 0ms, setup 0ms, collect 25ms, tests 534ms, environment 0ms, prepare 86ms)
+   Duration  800ms (transform 0ms, setup 0ms, collect 25ms, tests 534ms, environment 0ms, prepare 86ms)
+                   (shard=1/3 300ms, shard=2/3 250ms, shard=3/3 250ms)

Time of the --merge-reports should not be included in total time at all, I think.