Hey @beeplin can you expand on the problem? I am able to work with headers fine on the hello-world example.

@jasonkuhrt Please check https://github.com/beeplin/examples/commit/7ebb49e4096c8c3d171e87431805c36e1b201df2 to see my test.

Currently I dont' see any tests covering ctx.client.headers in the nexus/examples repo, so I made my own simple test in hello-world. Given a testHeader resolver returning the test header:

    t.field("testHeader", {
      type: "String",
      resolve(root, args, ctx) {
        return ctx.req.headers.test
      }
    })

And set test header with ctx.client.headers:

it("test headers", async () => {
  ctx.client.headers.set({ test: "this is a header test" })
  expect(
    await ctx.client.send(`
      query {
        testHeader
      }
    `)
  ).toMatchInlineSnapshot(`
    Object {
      "testHeader": "this is a header test",
    }
  `)
})

With the currently nexus 0.24.2 the test fails, and we can see the test header is not sent to the graphql client. With the fix shown in this PR, the test works.