✅ test(ports): Add no serial directory test

Author: NestorDP

CMakeLists.txt

@@ -140,6 +140,7 @@ if(BUILD_TESTING)
     add_executable(serial_tests
         test/test_serial_simple.cpp
         test/test_serial_pty.cpp
+        test/test_ports.cpp
     )
 
     target_include_directories(serial_tests PRIVATE

include/libserial/ports.hpp

@@ -40,6 +40,14 @@ class Ports {
  */
 Ports() = default;
 
+/**
+ * @brief Testable constructor allowing a custom system path
+ *
+ * Primarily intended for testing to inject a non-existent or
+ * non-readable directory to validate error handling paths.
+ */
+explicit Ports(const char* sys_path) : sys_path_(sys_path) {}
+
 /**
  * @brief Destroyer of the Ports class
  *
@@ -96,6 +104,11 @@ std::optional<std::string> findName(uint16_t id) const;
  */
 static constexpr const char* kSysSerialByIdPath = "/dev/serial/by-id/";
 
+/**
+ * @brief Configurable path used by scanPorts; defaults to kSysSerialByIdPath
+ */
+const char* sys_path_ { kSysSerialByIdPath };
+
 /**
  * @brief Internal list of detected serial devices
  */

src/ports.cpp

@@ -23,10 +23,10 @@ uint16_t Ports::scanPorts() {
 
   // Directory where udev creates symlinks for serial devices by ID
   // this directory may not exist if no serial devices are connected
-  const char* by_id_dir = kSysSerialByIdPath;
+  const char* by_id_dir = sys_path_;
   DIR* dir = opendir(by_id_dir);
   if (!dir) {
-    throw SerialException("Error while reading " + std::string(by_id_dir) + ": " + strerror(errno));
+    throw PortNotFoundException("Error while reading " + std::string(by_id_dir) + ": " + strerror(errno));
   }
 
   // The POSIX directory-entry structure used by readdir() to describe files

test/test_ports.cpp

@@ -0,0 +1,48 @@
+// Copyright 2020-2025 Nestor Neto
+
+#include <gtest/gtest.h>
+#include <memory>
+#include <string>
+
+// Include libserial headers
+#include "libserial/ports.hpp"
+#include "libserial/serial_exception.hpp"
+
+// Simple unit tests that don't require actual hardware
+class PortsTest : public ::testing::Test {
+protected:
+void SetUp() override {
+  // Test setup if needed
+}
+
+void TearDown() override {
+  // Test cleanup if needed
+}
+};
+
+TEST_F(PortsTest, DefaultConstructor) {
+  EXPECT_NO_THROW({
+    libserial::Ports ports;
+  });
+}
+
+TEST_F(PortsTest, ScanPortsThrowsWhenPathMissing) {
+  // Use an unlikely path to exist to trigger the exception path
+  const char* missing_path = "/this/path/should/not/exist/serial/by-id";
+  libserial::Ports ports(missing_path);
+
+
+  try {
+    (void)ports.scanPorts();
+  } catch (const libserial::SerialException& e) {
+    std::cout << "Caught SerialException: " << e.what() << std::endl;
+    // Optionally assert something about the message:
+    // EXPECT_NE(std::string(e.what()).find("Error while reading"), std::string::npos);
+  }
+
+  EXPECT_THROW({
+    (void)ports.scanPorts();
+  }, libserial::PortNotFoundException);
+}
+
+