mhweiner · mhweiner · Jun 13, 2025 · Jun 13, 2025
diff --git a/bin/cli.js b/bin/cli.js
@@ -1,3 +1,3 @@
 #!/usr/bin/env ts-node
 
-require('../dist/run');
+require('../dist/cli');
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -40,6 +40,7 @@
     "node-tap"
   ],
   "dependencies": {
+    "commander": "14.0.0",
     "deep-object-diff": "^1.1.0",
     "diff": "^5.0.0",
     "kleur": "^4.1.4",

diff --git a/src/cli.ts b/src/cli.ts
@@ -0,0 +1,21 @@
+import {Command} from 'commander';
+import {Flags, run} from './run';
+
+// eslint-disable-next-line @typescript-eslint/no-require-imports, @typescript-eslint/no-var-requires
+const packageJson = require('../package.json');
+const program = new Command();
+
+program
+    .name('kizu')
+    .version(packageJson.version, '-v, --version')
+    .description('⚫️ kizu\n\nAn easy-to-use, fast, and defensive Typescript/Javascript test runner designed to help you to write simple, readable, and maintainable tests.')
+    .option('--fail-only, -f', 'Only show failures in the output.', false)
+    .argument('<glob>', 'Glob pattern to match files to run tests on.')
+    .parse(process.argv);
+
+const flags = program.opts() as Flags;
+const filesGlob = program.args[0];
+
+run(flags, filesGlob).catch(console.log.bind(console));
+
+
diff --git a/src/getSpecFiles.ts b/src/getSpecFiles.ts
@@ -1,7 +1,7 @@
 import glob from 'tiny-glob';
 
-export async function getSpecFiles() {
+export async function getSpecFiles(arg: string) {
 
-    return glob(process.argv[2]);
+    return glob(arg);
 
 }
diff --git a/src/output.ts b/src/output.ts
@@ -18,29 +18,40 @@ The following spec files do not have any attempted or completed tests:
 ${files.join(', ')}
 `);
 
-export function printResultsByFile(resultsByFile: TestResultsByFile) {
+export function printResultsByFile(resultsByFile: TestResultsByFile, showOnlyFailures: boolean = false) {
 
     const sortedResults = sortTestResults(resultsByFile);
 
     for (const [filename, tests] of sortedResults) {
 
-        printFileResults(filename, tests);
+        printFileResults(filename, tests, showOnlyFailures);
 
     }
 
 }
 
-export function printFileResults(filename: string, tests: TestResults[]) {
+export function printFileResults(
+    filename: string,
+    tests: TestResults[],
+    showOnlyFailures: boolean = false
+) {
 
-    const doesFileHaveFailures = tests.some((test) => !isTestPassing(test));
-    const header = `${kleur.underline().blue(filename)} ${doesFileHaveFailures ? failureSymbol : successSymbol}\n`;
+    const hasFailure = tests.some((test) => !isTestPassing(test));
+
+    if (showOnlyFailures && !hasFailure) return;
+
+    const header = `${kleur.underline().blue(filename)} ${hasFailure ? failureSymbol : successSymbol}\n`;
 
     log(header);
     tests.forEach(((test) => {
 
+        if (showOnlyFailures && isTestPassing(test)) return;
+
         log(`${test.description} ${isTestPassing(test) ? successSymbol : failureSymbol}`);
         test.assertions.forEach((assertion) => {
 
+            if (showOnlyFailures && assertion.pass) return;
+
             log(kleur.gray(`  ${assertion.description} ${assertion.pass ? successSymbol : failureSymbol}`));
             !assertion.pass && printFailedAssertionDiag(assertion);
 

diff --git a/src/run.ts b/src/run.ts
@@ -9,6 +9,9 @@ import {getSpecFiles} from './getSpecFiles';
 const testResultsByFile: TestResultsByFile = {};
 let numCompletedTests = 0;
 
+export type Flags = {
+    failOnly: boolean
+};
 export type TestResultsByFile = {[file: string]: TestResults[]};
 export type FinalResults = {
     numFiles: number
@@ -21,14 +24,14 @@ export type FinalResults = {
 
 const status = ora();
 
-async function start() {
+export async function run(flags: Flags, filesGlob: string) {
 
-    const specFiles = await getSpecFiles();
+    const specFiles = await getSpecFiles(filesGlob);
 
     console.log(`Found ${specFiles.length} spec files.\n`);
     status.start('Running tests...');
     await workerPool(specFiles, addTestResults);
-    finish(specFiles);
+    showResults(flags, specFiles);
 
 }
 
@@ -45,16 +48,14 @@ function addTestResults(file: string, results: TestResults) {
 
 }
 
-function finish(specFiles: string[]) {
+function showResults(flags: Flags, specFiles: string[]) {
 
     status.stop();
 
     const finalResults = calculateFinalResults(specFiles, testResultsByFile);
 
-    printResultsByFile(testResultsByFile);
+    printResultsByFile(testResultsByFile, flags.failOnly);
     printSummary(finalResults);
     if (shouldExitWithError(finalResults)) process.exit(1);
 
 }
-
-start().catch(console.log.bind(console));