feat: Allow main module to export a function.

Author: ShogunPanda

README.md

@@ -39,6 +39,8 @@ Inside worker threads, the cronometro function invocation will return no value a
 
 You can use `isMainThread` from Worker Threads API to check in which environment the script is running.
 
+If your main module returns a function, cronometro will execute it before running tests. The function can also return a promise and that will be awaited.
+
 ## Usage
 
 To run a benchmark, simply call the `cronometro` function with the set of tests you want to run, then optionally provide a options object and a Node's style callback.

src/runner.ts

@@ -22,18 +22,23 @@ if (workerData.path.endsWith('.ts')) {
     })
   }
 }
-/* c8 ignore stop */
 
 // Require the script to set tests
 chain
   .then(() => {
     return import(workerData.path)
   })
+  .then((module: any) => {
+    if (typeof module === 'function') {
+      return module()
+    } else if (typeof module.default === 'function') {
+      return module.default()
+    }
+  })
   .then(() => {
     // Run the worker
     runWorker(workerData, (value: any) => parentPort!.postMessage(value), process.exit)
   })
-  /* c8 ignore start */
   .catch((e: Error) => {
     process.nextTick(() => {
       throw e

test/asyncImport.ts

@@ -0,0 +1,62 @@
+/* eslint-disable @typescript-eslint/no-floating-promises */
+
+import t from 'tap'
+import { isMainThread } from 'worker_threads'
+import { cronometro, percentiles } from '../src'
+
+type Test = typeof t
+
+async function main(): Promise<void> {
+  await new Promise((resolve: (value: unknown) => void) => setTimeout(resolve, 100))
+
+  if (!isMainThread) {
+    cronometro(
+      {
+        single() {
+          Buffer.alloc(10)
+        },
+        multiple() {
+          Buffer.alloc(10)
+          Buffer.alloc(20)
+        }
+      },
+      () => false
+    )
+  } else {
+    t.only('Collecting results', async (t: Test) => {
+      const results = await cronometro(
+        {
+          single() {
+            Buffer.alloc(10)
+          },
+          multiple() {
+            Buffer.alloc(10)
+            Buffer.alloc(20)
+          }
+        },
+        { iterations: 10, print: false }
+      )
+
+      t.strictSame(Object.keys(results), ['single', 'multiple'])
+
+      for (const entry of Object.values(results)) {
+        t.ok(entry.success)
+        t.type(entry.error, 'undefined')
+        t.equal(entry.size, 10)
+        t.type(entry.min, 'number')
+        t.type(entry.max, 'number')
+        t.type(entry.mean, 'number')
+        t.type(entry.stddev, 'number')
+        t.type(entry.standardError, 'number')
+
+        for (const percentile of percentiles) {
+          t.type(entry.percentiles[percentile.toString()], 'number')
+        }
+      }
+    })
+  }
+}
+
+main()
+
+export default main