1 files changed, 90 insertions, 0 deletions
diff --git a/test/cepis/retry_test.exs b/test/cepis/retry_test.exs
new file mode 100644
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+++ b/test/cepis/retry_test.exs
@@ -0,0 +1,90 @@
+defmodule Cepis.RetryTest do
+  use Cepis.ServerCase
+
+  test "a 500 is retried and the second attempt wins", %{server: server, client: client} do
+    FakeServer.respond(server, "/01001000", [
+      {500, json(%{"erro" => "interno"}), []},
+      {200, json(address_fixture()), []}
+    ])
+
+    assert {:ok, address} = Cepis.lookup("01001000", client)
+    assert address.localidade == "São Paulo"
+    assert FakeServer.count(server, "/01001000") == 2
+  end
+
+  test "attempts are exhausted and then it gives up", %{server: server, client: client} do
+    FakeServer.respond(server, "/01001000", {503, json(%{"erro" => "interno"}), []})
+
+    assert {:error, %Cepis.ServerError{status: 503}} = Cepis.lookup("01001000", client)
+    assert FakeServer.count(server, "/01001000") == 3
+  end
+
+  test "max_attempts: 1 disables retrying", %{server: server} do
+    client = Cepis.Client.new(base_url: server.url, max_attempts: 1, timeout: 5_000)
+    FakeServer.respond(server, "/01001000", {500, "{}", []})
+
+    assert {:error, %Cepis.ServerError{status: 500}} = Cepis.lookup("01001000", client)
+    assert FakeServer.count(server, "/01001000") == 1
+  end
+
+  test "a 429 exposes Retry-After in milliseconds", %{server: server, client: client} do
+    FakeServer.respond(server, "/01001000", {429, "{}", [{"retry-after", "7"}]})
+
+    assert {:error, %Cepis.RateLimitError{retry_after: 7_000}} = Cepis.lookup("01001000", client)
+  end
+
+  test "a Retry-After HTTP date is understood", %{server: server, client: client} do
+    date =
+      DateTime.utc_now()
+      |> DateTime.add(30, :second)
+      |> Calendar.strftime("%a, %d %b %Y %H:%M:%S GMT")
+
+    FakeServer.respond(server, "/01001000", {429, "{}", [{"retry-after", date}]})
+
+    assert {:error, %Cepis.RateLimitError{retry_after: retry_after}} =
+             Cepis.lookup("01001000", client)
+
+    assert retry_after > 20_000
+    assert retry_after <= 30_000
+  end
+
+  test "an absurd Retry-After cannot park the caller", %{server: server, client: client} do
+    FakeServer.respond(server, "/01001000", {429, "{}", [{"retry-after", "3600"}]})
+
+    {elapsed, result} = :timer.tc(fn -> Cepis.lookup("01001000", client) end, :millisecond)
+
+    assert {:error, %Cepis.RateLimitError{}} = result
+    assert elapsed < 2_000
+  end
+
+  test "nothing listening is a network error" do
+    client =
+      Cepis.Client.new(
+        base_url: "http://127.0.0.1:1",
+        max_attempts: 2,
+        backoff_base: 1,
+        timeout: 1_000
+      )
+
+    assert {:error, %Cepis.NetworkError{}} = Cepis.lookup("01001000", client)
+  end
+
+  test "total_timeout bounds the whole call", %{server: server} do
+    client =
+      Cepis.Client.new(
+        base_url: server.url,
+        max_attempts: 50,
+        backoff_base: 50,
+        backoff_max: 50,
+        total_timeout: 300
+      )
+
+    FakeServer.respond(server, "/01001000", {500, "{}", []})
+
+    {elapsed, result} = :timer.tc(fn -> Cepis.lookup("01001000", client) end, :millisecond)
+
+    assert {:error, %Cepis.ServerError{}} = result
+    assert elapsed < 3_000
+    assert FakeServer.count(server, "/01001000") < 50
+  end
+end