Warn about running on Snap

Closes #584

Author: gustavohenke

lib/assert.spec.ts

@@ -1,14 +1,17 @@
-import { afterEach, describe, expect, it, vi } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it, MockInstance, vi } from 'vitest';
 
-import { assertDeprecated } from './assert.js';
+import { assertDeprecated, assertNotRuntime } from './assert.js';
 
-describe('#assertDeprecated()', () => {
-    const consoleMock = vi.spyOn(console, 'warn').mockImplementation(() => {});
+let consoleMock: MockInstance;
+beforeEach(() => {
+    consoleMock = vi.spyOn(console, 'warn').mockImplementation(() => {});
+});
 
-    afterEach(() => {
-        vi.clearAllMocks();
-    });
+afterEach(() => {
+    vi.clearAllMocks();
+});
 
+describe('assertDeprecated()', () => {
     it('prints warning with name and message when condition is false', () => {
         assertDeprecated(false, 'example-flag', 'This is an example message.');
 
@@ -33,3 +36,29 @@ describe('#assertDeprecated()', () => {
         expect(consoleMock).not.toHaveBeenCalled();
     });
 });
+
+describe('assertNotRuntime()', () => {
+    it('prints warning with name and message when condition is false', () => {
+        assertNotRuntime(false, 'example-flag', 'This is an example message.');
+
+        expect(consoleMock).toHaveBeenLastCalledWith(
+            '[concurrently] Running via example-flag is not well supported. This is an example message.',
+        );
+    });
+
+    it('prints same warning only once', () => {
+        assertNotRuntime(false, 'example-flag', 'This is an example message.');
+        assertNotRuntime(false, 'different-flag', 'This is another message.');
+
+        expect(consoleMock).toBeCalledTimes(1);
+        expect(consoleMock).toHaveBeenLastCalledWith(
+            '[concurrently] Running via different-flag is not well supported. This is another message.',
+        );
+    });
+
+    it('prints nothing if condition is true', () => {
+        assertNotRuntime(true, 'example-flag', 'This is an example message.');
+
+        expect(consoleMock).not.toHaveBeenCalled();
+    });
+});

lib/assert.ts

@@ -11,3 +11,17 @@ export function assertDeprecated(check: boolean, name: string, message: string)
         deprecations.add(name);
     }
 }
+
+const runtimes = new Set<string>();
+
+/**
+ * Asserts that some condition is true, and if not, prints a warning about the runtime not being well supported.
+ * The message is printed only once.
+ */
+export function assertNotRuntime(check: boolean, name: string, message: string) {
+    if (!check && !runtimes.has(name)) {
+        // eslint-disable-next-line no-console
+        console.warn(`[concurrently] Running via ${name} is not well supported. ${message}`);
+        runtimes.add(name);
+    }
+}

lib/index.ts

@@ -1,7 +1,7 @@
 import process from 'node:process';
 import { Readable } from 'node:stream';
 
-import { assertDeprecated } from './assert.js';
+import { assertDeprecated, assertNotRuntime } from './assert.js';
 import { CloseEvent, Command, CommandIdentifier, TimerEvent } from './command.js';
 import {
     concurrently as createConcurrently,
@@ -127,6 +127,14 @@ export function concurrently(
     options: Partial<ConcurrentlyOptions> = {},
 ) {
     assertDeprecated(options.killOthers === undefined, 'killOthers', 'Use killOthersOn instead.');
+    assertNotRuntime(
+        // When run via /snap/bin/node, process.execPath maps to the actual snap path, but it also sets
+        // several SNAP_* env variables. If the snap is run directly via e.g. /snap/node/current/bin/node,
+        // the issues don't happen and no env variables are set.
+        !String(process.env.SNAP).startsWith('/snap'),
+        'Snap',
+        'Snap confinement can interfere with spawning child processes. See issue #584',
+    );
 
     // To avoid empty strings from hiding the output of commands that don't have a name,
     // keep in the list of commands to hide only strings with some length.