fix(registry): be better at using the correct registry (relevant for npme)

Closes #53

test/specs/get-registry.js

@@ -0,0 +1,30 @@
+const test = require('tap').test
+
+const getRegistry = require('../../dist/lib/get-registry')
+
+test('get correct registry', (t) => {
+  t.is(getRegistry({
+    name: 'publish-config',
+    publishConfig: {
+      registry: 'a'
+    }},
+  {}), 'a')
+
+  t.is(getRegistry({name: 'normal'}, {get: () => 'b'}), 'b')
+
+  t.is(getRegistry({name: 'normal'}, {get: () => null}), 'https://registry.npmjs.org/')
+
+  t.is(getRegistry({name: '@scoped/foo'}, {
+    get: (input) => input === '@scoped/registry' ? 'c' : 'd'
+  }), 'c')
+
+  t.is(getRegistry({name: '@scoped/bar'}, {
+    get: () => 'e'
+  }), 'e')
+
+  t.is(getRegistry({name: '@scoped/baz'}, {
+    get: () => null
+  }), 'https://registry.npmjs.org/')
+
+  t.end()
+})