Improve unit test for cloudwatch logger

Author: tckeong

lib/cadet/logger/cloudwatch_logger.ex

@@ -20,8 +20,9 @@ defmodule Cadet.Logger.CloudWatchLogger do
 
   @max_buffer_size 1000
   @max_retries 3
-  @retry_delay 500
+  @retry_delay 200
   @flush_interval 5000
+  @failed_message "Failed to send log to CloudWatch."
 
   @impl true
   def init({__MODULE__, opts}) when is_list(opts) do
@@ -113,14 +114,19 @@ defmodule Cadet.Logger.CloudWatchLogger do
     init(config, state)
   end
 
+  defp normalize_level(lvl) when lvl in [:warn, :warning], do: :warning
+  defp normalize_level(lvl), do: lvl
+
   defp meet_level?(_lvl, nil), do: true
 
   defp meet_level?(lvl, min) do
+    lvl = normalize_level(lvl)
+    min = normalize_level(min)
     Logger.compare_levels(lvl, min) != :lt
   end
 
   defp meet_cloudwatch_error?(msg) when is_binary(msg) do
-    String.starts_with?(msg, "Failed to send log to CloudWatch")
+    String.contains?(msg, @failed_message)
   end
 
   defp meet_cloudwatch_error?(_) do
@@ -182,16 +188,14 @@ defmodule Cadet.Logger.CloudWatchLogger do
     cond do
       is_nil(id) or id == "" or is_nil(secret) or secret == "" ->
         Logger.error(
-          "Failed to send log to CloudWatch. AWS credentials missing. Ensure AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are set.
-        "
+          "#{@failed_message} AWS credentials missing. Ensure AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are set or configured in ex_aws."
         )
 
         :error
 
       region in [nil, ""] ->
         Logger.error(
-          "Failed to send log to CloudWatch. AWS region not configured. Set AWS_REGION or :region under :ex_aws in config.
-        "
+          "#{@failed_message} AWS region not configured. Ensure AWS_REGION is set or configured in ex_aws."
         )
 
         :error
@@ -209,15 +213,15 @@ defmodule Cadet.Logger.CloudWatchLogger do
         :ok
 
       {:error, reason} ->
-        Logger.error("Failed to send log to CloudWatch: #{inspect(reason)}. Retrying...")
+        Logger.error("#{@failed_message} #{inspect(reason)}. Retrying...")
         # Wait before retrying
         :timer.sleep(@retry_delay)
         send_with_retry(operation, retries - 1)
     end
   end
 
   defp send_with_retry(_, 0) do
-    Logger.error("Failed to send log to CloudWatch after multiple retries.")
+    Logger.error("#{@failed_message} After multiple retries.")
   end
 
   defp init(config, state) do

test/cadet/logger/cloudwatch_logger_test.exs

@@ -1,5 +1,6 @@
 defmodule Cadet.Logger.CloudWatchLoggerTest do
   use ExUnit.Case, async: false
+
   require Logger
   import Mox
   alias Cadet.Logger.CloudWatchLogger
@@ -15,36 +16,27 @@ defmodule Cadet.Logger.CloudWatchLoggerTest do
       level: :info,
       log_group: "test_log_group",
       log_stream: "test_log_stream",
-      buffer_size: 10,
       format: "$time $metadata[$level] $message",
       metadata: [:request_id]
     )
 
     LoggerBackends.add({CloudWatchLogger, :cloudwatch_logger})
 
+    Logger.configure_backend(:console, level: :error)
+
     on_exit(fn ->
       LoggerBackends.remove({CloudWatchLogger, :cloudwatch_logger})
+      Logger.configure_backend(:console, level: :warning)
     end)
 
     :ok
   end
 
   test "flushes buffered events via ExAws" do
     expect(ExAwsMock, :request, fn %ExAws.Operation.JSON{} = op ->
-      IO.puts("ExAws request: #{inspect(op)}")
-      %{http_method: http_method, data: data, headers: headers, service: service} = op
-
-      assert http_method == :post
-      assert service == :logs
+      %{data: data} = op
 
-      assert headers == [
-               {"x-amz-target", "Logs_20140328.PutLogEvents"},
-               {"content-type", "application/x-amz-json-1.1"}
-             ]
-
-      assert data["logGroupName"] == "test_log_group"
-      assert data["logStreamName"] == "test_log_stream"
-      assert is_list(data["logEvents"])
+      assert_config(op)
 
       assert Enum.all?(data["logEvents"], fn event ->
                is_map(event) and
@@ -55,8 +47,11 @@ defmodule Cadet.Logger.CloudWatchLoggerTest do
       assert Enum.all?(
                data["logEvents"],
                fn event ->
-                 String.contains?(event["message"], "[error] this is an error") or
-                   String.contains?(event["message"], "[warn] this is a warning")
+                 is_map(event) and
+                   Map.has_key?(event, "message") and
+                   (String.contains?(event["message"], "[error] this is an error") or
+                      String.contains?(event["message"], "[warning] this is a warning") or
+                      String.contains?(event["message"], "[warn] this is a warning"))
                end
              )
 
@@ -67,9 +62,70 @@ defmodule Cadet.Logger.CloudWatchLoggerTest do
     end)
 
     Logger.error("this is an error")
-    Logger.warn("this is a warning")
+    Logger.warning("this is a warning")
 
-    # wait for async flush
+    # wait for timer to flush the buffer
     Process.sleep(5100)
   end
+
+  test "Force flush the buffer when the buffer size is reached" do
+    expect(ExAwsMock, :request, fn %ExAws.Operation.JSON{} = op ->
+      %{data: data} = op
+
+      assert_config(op)
+
+      assert Enum.all?(data["logEvents"], fn event ->
+               is_map(event) and
+                 Map.has_key?(event, "timestamp") and
+                 Map.has_key?(event, "message")
+             end)
+
+      assert Enum.all?(
+               data["logEvents"],
+               fn event ->
+                 is_map(event) and
+                   Map.has_key?(event, "message") and
+                   (String.contains?(event["message"], "[warning] this is a warning") or
+                      String.contains?(event["message"], "[warn] this is a warning"))
+               end
+             )
+
+      {:ok,
+       %{
+         status_code: 200
+       }}
+    end)
+
+    for _ <- 1..1000 do
+      Logger.warning("this is a warning")
+    end
+
+    # don't wait for timer
+    Process.sleep(100)
+  end
+
+  test "Failed to send log to CloudWatch" do
+    expect(ExAwsMock, :request, 3, fn %ExAws.Operation.JSON{} = op ->
+      assert_config(op)
+
+      {:error, "Failed to send log to CloudWatch"}
+    end)
+
+    Logger.warning("this is a warning")
+
+    Process.sleep(6000)
+  end
+
+  defp assert_config(%{http_method: http_method, data: data, headers: headers, service: service}) do
+    assert http_method == :post
+    assert service == :logs
+
+    assert headers == [
+             {"x-amz-target", "Logs_20140328.PutLogEvents"},
+             {"content-type", "application/x-amz-json-1.1"}
+           ]
+
+    assert data["logGroupName"] == "test_log_group"
+    assert data["logStreamName"] == "test_log_stream"
+  end
 end