File size impact

Merging issue-2293 into master will impact 1 file in 1 group.

Is it possible to get a test to cover this case?

Not without some reworking of the tests - currently the amd.js extra is executed before the named-register extra, which alters behavior in such a way that the test would pass both with and without the new code.

Released in https://github.com/systemjs/systemjs/releases/tag/6.9.0

FYI, this appears to be a breaking change with respect to previous behavior. After updating to 6.9.0, System.import() now returns the last named register module instead of the actual module fetched from the URL. For example, at initialization, I do

const lib1Exports = ...
const lib2Exports = ...
System.register('lib1', [],  _export => {
  return {
    execute: () => {
      _export(lib1Exports)
      // deliberate undefined return because returning something here screws up systemjs
      return void(0)
    }
  }
})
System.register('lib2', [], _export => {
  return {
    execute: () => {
      _export(lib2Exports)
      return void(0)
    }
  }
})

Then later

const lib3 = await System.import('/libs/lib3.umd.js')
!!lib3.lib2Member // true

The above worked as expected with version 6.8.x and the named-register/amd extras.

See this sandbox that demonstrates the issue. You'll need to comment/uncomment the script elements as necessary to switch between SystemJS versions. https://codesandbox.io/s/epic-goldstine-r1qio?file=/index.html