Add mock data and unit tests for Channels and Members APIs

test/unit/lang/assertUnreachable.test.ts

@@ -0,0 +1,31 @@
+import {describe, expect, it} from 'bun:test';
+import assertUnreachable from '../../../src/lang/assertUnreachable';
+
+describe('assertUnreachable', () => {
+  describe('when called with an unexpected value', () => {
+    it('should throw an error containing the value', () => {
+      const unreachableValue = 'unexpected' as never;
+
+      expect(() => assertUnreachable(unreachableValue)).toThrow('Unreachable code: unexpected');
+    });
+
+    it('should handle numeric values in the error message', () => {
+      const numericValue = 42 as never;
+
+      expect(() => assertUnreachable(numericValue)).toThrow('Unreachable code: 42');
+    });
+
+    it('should always throw and never return', () => {
+      const value = 'test' as never;
+      let didThrow = false;
+
+      try {
+        assertUnreachable(value);
+      } catch {
+        didThrow = true;
+      }
+
+      expect(didThrow).toBe(true);
+    });
+  });
+});