feat: isShellSupported

lib/index.js

@@ -11,6 +11,13 @@ const { tabtabDebug, systemShell } = require('./utils');
 // TABTAB_DEBUG file provided.
 const debug = tabtabDebug('tabtab');
 
+/**
+ * Check if a shell is supported.
+ * @param {String} shell - Shell to check.
+ * @returns {shell is SupportedShell}
+ */
+const isShellSupported = shell => (/** @type {ReadonlyArray.<String>} */ (SUPPORTED_SHELLS)).includes(shell);
+
 /**
  * Construct a completion script.
  * @param {Object} options - Options object.
@@ -247,6 +254,7 @@ const logFiles = () => {
 module.exports = {
   SUPPORTED_SHELLS,
   shell: systemShell,
+  isShellSupported,
   getCompletionScript,
   install,
   uninstall,

test/isShellSupported.js

@@ -0,0 +1,15 @@
+const assert = require('assert');
+const { isShellSupported, SUPPORTED_SHELLS } = require('..');
+
+describe('isShellSupported', () => {
+  it('returns true for supported shells', () => {
+    assert.deepStrictEqual(
+      SUPPORTED_SHELLS.filter(shell => isShellSupported(shell)),
+      SUPPORTED_SHELLS,
+    );
+  })
+
+  it('returns false for unsupported shells', () => {
+    assert.strictEqual(isShellSupported('unknown'), false);
+  })
+})