feat: add support for oauth whitelist file (#817)

internal/utils/string_utils_test.go

@@ -1,6 +1,7 @@
 package utils_test
 
 import (
+	"os"
 	"testing"
 
 	"github.com/tinyauthapp/tinyauth/internal/utils"
@@ -57,3 +58,33 @@ func TestCompileUserEmail(t *testing.T) {
 	// Test with invalid email
 	assert.Equal(t, "user@example.com", utils.CompileUserEmail("user", "example.com"))
 }
+
+func TestParseNonEmptyLines(t *testing.T) {
+	lines := utils.ParseNonEmptyLines(" first@example.com \n\n second@example.com \n   \n")
+
+	assert.DeepEqual(t, []string{"first@example.com", "second@example.com"}, lines)
+}
+
+func TestGetStringList(t *testing.T) {
+	file, err := os.Create("/tmp/tinyauth_list_test_file")
+	assert.NilError(t, err)
+
+	_, err = file.WriteString(" third@example.com \n\n fourth@example.com \n")
+	assert.NilError(t, err)
+
+	err = file.Close()
+	assert.NilError(t, err)
+	defer os.Remove("/tmp/tinyauth_list_test_file")
+
+	values, err := utils.GetStringList([]string{" first@example.com ", "", "second@example.com"}, "/tmp/tinyauth_list_test_file")
+	assert.NilError(t, err)
+	assert.DeepEqual(t, []string{"first@example.com", "second@example.com", "third@example.com", "fourth@example.com"}, values)
+
+	values, err = utils.GetStringList(nil, "")
+	assert.NilError(t, err)
+	assert.DeepEqual(t, []string{}, values)
+
+	values, err = utils.GetStringList(nil, "/tmp/non_existing_list_file")
+	assert.ErrorContains(t, err, "no such file or directory")
+	assert.DeepEqual(t, []string{}, values)
+}