PathParams middleware

lib/tesla/middleware/path_params.ex

@@ -0,0 +1,14 @@
+defmodule Tesla.Middleware.PathParams do
+  @behaviour Tesla.Middleware
+
+  @impl true
+  def call(env, next, _) do
+    url = build_url(env.url, env.opts[:path_params])
+    Tesla.run(%{env | url: url}, next)
+  end
+
+  defp build_url(url, nil), do: url
+
+  defp build_url(url, params),
+    do: Enum.reduce(params, url, fn {k, v}, u -> String.replace(u, ":#{k}", to_string(v)) end)
+end

test/tesla/middleware/path_params_test.exs

@@ -0,0 +1,17 @@
+defmodule Tesla.Middleware.PathParamsTest do
+  use ExUnit.Case, async: true
+  alias Tesla.Env
+
+  @middleware Tesla.Middleware.PathParams
+
+  test "no params" do
+    assert {:ok, env} = @middleware.call(%Env{url: "/users/:id"}, [], nil)
+    assert env.url == "/users/:id"
+  end
+
+  test "passed params" do
+    opts = [path_params: [id: 42]]
+    assert {:ok, env} = @middleware.call(%Env{url: "/users/:id", opts: opts}, [], nil)
+    assert env.url == "/users/42"
+  end
+end