diff --git a/test/datasource/cargo/index.spec.js b/test/datasource/cargo/index.spec.js
new file mode 100644
index 0000000000000000000000000000000000000000..48c97b893f359fba5a48c9be2588a2a3addb06ff
--- /dev/null
+++ b/test/datasource/cargo/index.spec.js
@@ -0,0 +1,15 @@
+const cargo = require('../../../lib/datasource/cargo');
+
+describe('cargo datasource', () => {
+  beforeEach(() => {
+    return global.renovateCache.rmAll();
+  });
+  it('should use global cache', async () => {
+    const dep = {
+      name: 'abc123',
+    };
+    await global.renovateCache.set('datasource-cargo', 'foobar', dep, 10);
+    const res = await cargo.getPkgReleases({ lookupName: 'foobar' });
+    expect(res).toEqual(dep);
+  });
+});