feat(log): implement custom error log filter to suppress "context can… (#470)

* feat(log): implement custom error log filter to suppress "context canceled" messages

fixes #446

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat(log): suppress 'context canceled' errors in HTTP logs

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

---------

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

internal/log_test.go

@@ -0,0 +1,46 @@
+package internal
+
+import (
+	"bytes"
+	"log"
+	"strings"
+	"testing"
+)
+
+func TestErrorLogFilter(t *testing.T) {
+	var buf bytes.Buffer
+	destLogger := log.New(&buf, "", 0)
+	errorFilterWriter := &ErrorLogFilter{Unwrap: destLogger}
+	testErrorLogger := log.New(errorFilterWriter, "", 0)
+
+	// Test Case 1: Suppressed message
+	suppressedMessage := "http: proxy error: context canceled"
+	testErrorLogger.Println(suppressedMessage)
+
+	if buf.Len() != 0 {
+		t.Errorf("Suppressed message was written to output. Output: %q", buf.String())
+	}
+	buf.Reset()
+
+	// Test Case 2: Allowed message
+	allowedMessage := "http: another error occurred"
+	testErrorLogger.Println(allowedMessage)
+
+	output := buf.String()
+	if !strings.Contains(output, allowedMessage) {
+		t.Errorf("Allowed message was not written to output. Output: %q", output)
+	}
+	if !strings.HasSuffix(output, "\n") {
+		t.Errorf("Allowed message output is missing newline. Output: %q", output)
+	}
+	buf.Reset()
+
+	// Test Case 3: Partially matching message (should be suppressed)
+	partiallyMatchingMessage := "Some other log before http: proxy error: context canceled and after"
+	testErrorLogger.Println(partiallyMatchingMessage)
+
+	if buf.Len() != 0 {
+		t.Errorf("Partially matching message was written to output. Output: %q", buf.String())
+	}
+	buf.Reset()
+}