diff --git a/src/registry/RedundantRegistryClient.ts b/src/registry/RedundantRegistryClient.ts
index a7caf9b..b4b3a04 100644
--- a/src/registry/RedundantRegistryClient.ts
+++ b/src/registry/RedundantRegistryClient.ts
@@ -5,7 +5,7 @@ import { RegistryClient, RegistryClientOptions } from './RegistryClient';
 export class RedundantRegistryClient implements RegistryClient {
   protected log: LogFunction;
   constructor(
-    private clients: RegistryClient[],
+    public clients: RegistryClient[],
     options: RegistryClientOptions = {}
   ) {
     this.log = options.log ?? (() => {});
diff --git a/test/registry/RedundantRegistryClient.test.ts b/test/registry/RedundantRegistryClient.test.ts
new file mode 100644
index 0000000..ab16c29
--- /dev/null
+++ b/test/registry/RedundantRegistryClient.test.ts
@@ -0,0 +1,77 @@
+import { RedundantRegistryClient } from '../../src/registry/RedundantRegistryClient';
+import { loggerSpy } from '../testhelpers';
+import { Readable } from 'stream';
+
+class MyMockClient {
+  public endpoint: string;
+  constructor(endpoint: string) {
+    this.endpoint = endpoint;
+  }
+
+  async download(name: string, version: string): Promise<Readable> {
+    // to mimic failure of download
+    if (this.endpoint == 'failed.to.download') throw new Error('Failed to download');
+
+    return Readable.from([
+      `MyMockDownload of ${name}#${version} from ${this.endpoint}/${name}/${version}`
+    ]);
+  }
+}
+
+describe('RedundantRegistryClient', () => {
+  describe('#download', () => {
+    beforeEach(() => {
+      loggerSpy.reset();
+    });
+
+    it('should download the first client specified (FHIR client)', async () => {
+      const mockClient1 = new MyMockClient('https://packages.fhir.org');
+      const mockClient2 = new MyMockClient('failed.to.download');
+      const client = new RedundantRegistryClient([mockClient1, mockClient2], {
+        log: loggerSpy.log
+      });
+      const latest = await client.download('hl7.terminology.r4', '1.1.2');
+
+      // should get first client specified that doesn't throw error
+      expect(latest).toBeDefined();
+      expect(latest).toBeInstanceOf(Readable);
+      expect(latest.read()).toBe(
+        'MyMockDownload of hl7.terminology.r4#1.1.2 from https://packages.fhir.org/hl7.terminology.r4/1.1.2'
+      );
+    });
+
+    it('should download the second client specified (NPM client) if first is unable to download', async () => {
+      const mockClient1 = new MyMockClient('failed.to.download');
+      const mockClient2 = new MyMockClient('https://packages-second-client.fhir.org');
+      const client = new RedundantRegistryClient([mockClient1, mockClient2], {
+        log: loggerSpy.log
+      });
+      const latest = await client.download('hl7.terminology.r4', '1.1.2');
+
+      // will get second client specified since first throw error and goes to next client
+      expect(latest).toBeDefined();
+      expect(latest).toBeInstanceOf(Readable);
+      expect(latest.read()).toBe(
+        'MyMockDownload of hl7.terminology.r4#1.1.2 from https://packages-second-client.fhir.org/hl7.terminology.r4/1.1.2'
+      );
+    });
+
+    it('should throw error when no package server provided', async () => {
+      const client = new RedundantRegistryClient([], { log: loggerSpy.log });
+      const latest = client.download('hl7.terminology.r4', '1.1.2');
+      expect(latest).rejects.toThrow(Error);
+      expect(latest).rejects.toThrow('Failed to download hl7.terminology.r4#1.1.2');
+    });
+
+    it('should throw error when all package servers provided fail', async () => {
+      const mockClient1 = new MyMockClient('failed.to.download');
+      const mockClient2 = new MyMockClient('failed.to.download');
+      const client = new RedundantRegistryClient([mockClient1, mockClient2], {
+        log: loggerSpy.log
+      });
+      const latest = client.download('hl7.terminology.r4', '1.1.2');
+      expect(latest).rejects.toThrow(Error);
+      expect(latest).rejects.toThrow('Failed to download hl7.terminology.r4#1.1.2');
+    });
+  });
+});