Tesla.Mock (tesla v1.4.2) View Source

Mock adapter for better testing.

Setup

# config/test.exs
config :tesla, adapter: Tesla.Mock

# in case MyClient defines specific adapter with `adapter SpecificAdapter`
config :tesla, MyClient, adapter: Tesla.Mock

Examples

defmodule MyAppTest do
  use ExUnit.Case

  setup do
    Tesla.Mock.mock(fn
      %{method: :get} ->
        %Tesla.Env{status: 200, body: "hello"}
    end)

    :ok
  end

  test "list things" do
    assert {:ok, env} = MyApp.get("...")
    assert env.status == 200
    assert env.body == "hello"
  end
end

Setting up mocks

# Match on method & url and return whole Tesla.Env
Tesla.Mock.mock(fn
  %{method: :get, url: "http://example.com/list"} ->
    %Tesla.Env{status: 200, body: "hello"}
end)

# You can use any logic required
Tesla.Mock.mock(fn env ->
  case env.url do
    "http://example.com/list" ->
      %Tesla.Env{status: 200, body: "ok!"}

    _ ->
      %Tesla.Env{status: 404, body: "NotFound"}
  end
end)


# mock will also accept short version of response
# in the form of {status, headers, body}
Tesla.Mock.mock(fn
  %{method: :post} -> {201, %{}, %{id: 42}}
end)

Global mocks

By default, mocks are bound to the current process, i.e. the process running a single test case. This design allows proper isolation between test cases and make testing in parallel (async: true) possible.

While this style is recommended, there is one drawback: if Tesla client is called from different process it will not use the setup mock.

To solve this issue it is possible to setup a global mock using mock_global/1 function.

defmodule MyTest do
  use ExUnit.Case, async: false # must be false!

  setup_all do
    Tesla.Mock.mock_global fn
      env -> # ...
    end

    :ok
  end

  # ...
end

WARNING: Using global mocks may affect tests with local mock (because of fallback to global mock in case local one is not found)

Link to this section Summary

Functions

Return JSON response.

Setup mocks for current test.

Setup global mocks.

Return text response.

Link to this section Types

Specs

response_opt() :: :headers | :status

Specs

response_opts() :: [{response_opt(), any()}]

Link to this section Functions

Specs

json(body :: term(), opts :: response_opts()) :: Tesla.Env.t()

Return JSON response.

Example

import Tesla.Mock

mock fn
  %{url: "/ok"} -> json(%{"some" => "data"})
  %{url: "/404"} -> json(%{"some" => "data"}, status: 404)
end

Specs

mock((Tesla.Env.t() -> Tesla.Env.t() | {integer(), map(), any()})) ::
  no_return()

Setup mocks for current test.

This mock will only be available to the current process.

Specs

mock_global((Tesla.Env.t() -> Tesla.Env.t() | {integer(), map(), any()})) ::
  no_return()

Setup global mocks.

WARNING: This mock will be available to ALL processes. It might cause conflicts when running tests in parallel!

Specs

text(body :: term(), opts :: response_opts()) :: Tesla.Env.t()

Return text response.

Example

import Tesla.Mock

mock fn
  %{url: "/ok"} -> text(%{"some" => "data"})
  %{url: "/404"} -> text(%{"some" => "data"}, status: 404)
end