feat: set worker count from cli (#14)

* feat: basic worker setting support

* ci: enable in CI

* refactor: split off argument parser

* feat: generate helptext from flag configuration

.github/workflows/nodejs.yml

@@ -70,7 +70,7 @@ jobs:
         key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/yarn.lock') }}-node-${{ matrix.node-version }}
     - run: |
         yarn
-        yarn test
+        yarn test --workers=2
   
   build:
     runs-on: ubuntu-latest

src/argumentParser.ts

@@ -0,0 +1,69 @@
+import { type Args, type FlagConfigurationMap } from './types'
+
+export const FLAG_CONFIGURATION: Readonly<FlagConfigurationMap> = {
+	workers: {
+		requiresValue: true,
+		default: 1,
+		description: 'Defines up to how many parallel processes should consume tests.',
+	},
+	help: {
+		requiresValue: false,
+		default: false,
+		description: 'Displays the help text.',
+	},
+}
+
+class MalformedArgumentError extends Error {}
+
+function parseFlags(flags: Array<string>): Map<string, string | number | boolean> {
+	const flagMap = new Map<string, string | number | boolean>()
+
+	for (const flag of flags) {
+		const [flagName, flagValue] = flag.split('=') as Array<string>
+		const flagNameWithoutPrefix = flagName.replace(/^--/, '')
+		const flagConfiguration = FLAG_CONFIGURATION[flagNameWithoutPrefix]
+
+		if (!flagConfiguration) throw new MalformedArgumentError(`"${flagName}" is not a valid flag.`)
+
+		if (flagConfiguration.requiresValue && !flagValue)
+			throw new MalformedArgumentError(`"${flagName}" requires a value.`)
+
+		flagMap.set(flagNameWithoutPrefix, flagValue ?? true)
+	}
+
+	return flagMap
+}
+
+function parseArgs(args: Array<string>): Args {
+	const [, runtimePath, ...userArgs] = args
+
+	const {
+		argsWithoutFlags,
+		flags,
+	}: {
+		argsWithoutFlags: Array<string>
+		flags: Array<string>
+	} = (userArgs as Array<string>).reduce(
+		(acc, arg: string) => {
+			if (arg.startsWith('--')) acc.flags.push(arg)
+			else acc.argsWithoutFlags.push(arg)
+
+			return acc
+		},
+		{ argsWithoutFlags: [], flags: [] } as {
+			argsWithoutFlags: Array<string>
+			flags: Array<string>
+		},
+	)
+
+	const parsedFlags = parseFlags(flags)
+
+	return {
+		runtimePath,
+		targets: argsWithoutFlags ?? [],
+		help: Boolean(parsedFlags.get('help') ?? FLAG_CONFIGURATION['help'].default),
+		workers: Number(parsedFlags.get('workers') ?? FLAG_CONFIGURATION['workers'].default),
+	}
+}
+
+export default parseArgs

src/help.ts

@@ -1,12 +1,31 @@
 import { boldText } from './utils'
+import { FLAG_CONFIGURATION } from './argumentParser'
+
+function getFlagHelp(): string {
+	const lines: Array<string> = []
+
+	for (const flag of Object.keys(FLAG_CONFIGURATION)) {
+		const requiresValue = FLAG_CONFIGURATION[flag].requiresValue
+		lines.push(
+			[
+				`--${flag}${requiresValue ? '=<x>' : ''}`,
+				`${FLAG_CONFIGURATION[flag].description} (default=${FLAG_CONFIGURATION[flag].default})`,
+			]
+				.map((segment) => segment.padEnd(15))
+				.join(''),
+		)
+	}
+
+	return lines.join('\n')
+}
 
 export default `
 ${boldText('Works on my machine v0.0.0')}
 
 A no-dependency test runner
 ---
-womm [--help] [-h] ...<test-files-or-directories>
+womm <flags> ...<test-files-or-directories>
 
-Flags:
---help, -h: Prints this message
+${boldText('Flags:')}
+${getFlagHelp()}
 `

src/runner.ts

@@ -3,12 +3,15 @@
 import { getContext, greenText, redText, exec, splitIntoBatches } from './utils'
 import helpText from './help'
 import { type Args, type IContext, type TestServer } from './types'
+import parseArgs from './argumentParser'
 import { type Buffer } from 'buffer'
 
 import { promises as fs } from 'fs'
 import path from 'path'
 import net from 'net'
 
+class UnknownArgumentError extends Error {}
+
 /*
  * Collects test files recursively starting from the provided root
  * path.
@@ -90,39 +93,6 @@ function setUpSocket(socketPath: string): TestServer {
 	})
 
 	return server
-}
-
-function parseArgs(args: Array<string>): Args {
-	const [, runtimePath, ...userArgs] = args
-
-	const {
-		argsWithoutFlags,
-		shortFlags,
-		longFlags,
-	}: {
-		argsWithoutFlags: Array<string>
-		longFlags: Array<string>
-		shortFlags: Array<string>
-	} = (userArgs as Array<string>).reduce(
-		(acc, arg: string) => {
-			if (arg.startsWith('--')) acc.longFlags.push(arg)
-			else if (arg.startsWith('-')) acc.shortFlags.push(arg)
-			else acc.argsWithoutFlags.push(arg)
-
-			return acc
-		},
-		{ argsWithoutFlags: [], longFlags: [], shortFlags: [] } as {
-			argsWithoutFlags: Array<string>
-			longFlags: Array<string>
-			shortFlags: Array<string>
-		},
-	)
-
-	return {
-		runtimePath,
-		targets: argsWithoutFlags,
-		help: longFlags.includes('--help') || shortFlags.includes('-h'),
-	}
 } /*
  * Logic executed when running the test runner CLI.
  */
@@ -142,7 +112,7 @@ function parseArgs(args: Array<string>): Args {
 		const collectedTests = await collectTests(args.targets)
 		await collectCases(context, collectedTests)
 
-		await assignTestsToWorkers(context, collectedTests)
+		await assignTestsToWorkers(context, collectedTests, args.workers)
 
 		if (server.failure) throw new Error()
 	} catch (e) {

src/types.ts

@@ -22,6 +22,7 @@ export interface Args {
 	targets: Array<string>
 	runtimePath: string
 	help: boolean
+	workers: number
 }
 
 export interface MatcherReport {
@@ -45,3 +46,13 @@ export interface RawMatchersMap {
 	comparisonMatchers: Array<RawComparisonMatcher>
 	noArgMatchers: Array<RawNoArgMatcher>
 }
+
+interface FlagConfiguration {
+	requiresValue: boolean
+	default: string | boolean | number
+	description: string
+}
+
+export interface FlagConfigurationMap {
+	[key: string]: FlagConfiguration
+}