diff --git a/test/lib/prefix.js b/test/lib/prefix.js
new file mode 100644
index 0000000000000..a6e4d731ab187
--- /dev/null
+++ b/test/lib/prefix.js
@@ -0,0 +1,19 @@
+const { test } = require('tap')
+const requireInject = require('require-inject')
+
+test('prefix', (t) => {
+  t.plan(3)
+  const dir = '/prefix/dir'
+
+  const prefix = requireInject('../../lib/prefix.js', {
+    '../../lib/npm.js': { prefix: dir },
+    '../../lib/utils/output.js': (output) => {
+      t.equal(output, dir, 'prints the correct directory')
+    }
+  })
+
+  prefix([], (err) => {
+    t.ifError(err, 'npm prefix')
+    t.ok('should have printed directory')
+  })
+})