添加说明文档，为cangjie层添加单元测试

src/lua_runner_test.cj

@@ -0,0 +1,176 @@
+package luacangjie_api
+
+import std.unittest.*
+import std.fs.*
+
+let scriptsDir = "./test/scripts"
+
+// ====================
+// 1. 基础运行与参数测试
+// ====================
+
+@Test
+func testRunScript(): Unit {
+    let runner = LuaRunner()
+    let path = scriptsDir + "/simple_return.lua"
+    let res = runner.runScript(path, "")
+    @Expect(res, "hello")
+}
+
+@Test
+func testRunScriptWithArg(): Unit {
+    let runner = LuaRunner()
+    let path = scriptsDir + "/args_test.lua"
+    let res = runner.runScript(path, "world")
+    @Expect(res, "world")
+}
+
+// ====================
+// 2. 异常处理测试
+// ====================
+
+@Test
+func testRunScriptSyntaxError(): Unit {
+    let runner = LuaRunner()
+    let path = scriptsDir + "/syntax_error.lua"
+    try {
+        runner.runScript(path, "")
+        fail("Should throw syntax error")
+    } catch (e: LuaError) {
+        @Expect(e.code, 5010)
+    }
+}
+
+@Test
+func testRunScriptRuntimeError(): Unit {
+    let runner = LuaRunner()
+    let path = scriptsDir + "/runtime_error.lua"
+    try {
+        runner.runScript(path, "")
+        fail("Should throw runtime error")
+    } catch (e: LuaError) {
+        @Expect(e.code, 5010)
+    }
+}
+
+// ====================
+// 3. 库加载测试
+// ====================
+
+@Test
+func testLoadLib(): Unit {
+    let runner = LuaRunner()
+    let path = scriptsDir + "/mylib.lua"
+    runner.load(path, "mylib")
+}
+
+@Test
+func testLoadLibFileNotFound(): Unit {
+    let runner = LuaRunner()
+    try {
+        runner.load("/no/such/file.lua", "badlib")
+        fail("Should throw file not found error")
+    } catch (e: LuaError) {
+        @Expect(e.code, 5003)
+    }
+}
+
+@Test
+func testUnloadLib(): Unit {
+    let runner = LuaRunner()
+    let path = scriptsDir + "/mylib.lua"
+    runner.load(path, "mylib")
+    runner.unload("mylib")
+}
+
+@Test
+func testUnloadLibNotFound(): Unit {
+    let runner = LuaRunner()
+    try {
+        runner.unload("nosuchlib")
+        fail("Should throw exception")
+    } catch (e: LuaError) {
+        @Expect(e.code, 5012)
+    }
+}
+
+// ====================
+// 4. 状态管理与数据交互
+// ====================
+
+@Test
+func testCleanup(): Unit {
+    let runner = LuaRunner()
+    let setPath = scriptsDir + "/set_global.lua"
+    let getPath = scriptsDir + "/get_global.lua"
+
+    runner.runScript(setPath, "")
+    runner.clear()
+    let res = runner.runScript(getPath, "")
+    @Expect(res, "nil")
+}
+
+@Test
+func testCrossCallDataPassing(): Unit {
+    let runner = LuaRunner()
+    let setPath = scriptsDir + "/cross_call_set.lua"
+    let getPath = scriptsDir + "/cross_call_get.lua"
+
+    runner.runScript(setPath, "")
+    let res = runner.runScript(getPath, "")
+    @Expect(res, "1,2,3")
+}
+
+// ====================
+// 5. I/O 重定向测试
+// ====================
+
+@Test
+func testRedirectPrint(): Unit {
+    let runner = LuaRunner(pathio: "/tmp")
+    let path = scriptsDir + "/print_test.lua"
+    runner.runScript(path, "")
+}
+
+@Test
+func testRedirectIoWrite(): Unit {
+    let runner = LuaRunner(pathio: "/tmp")
+    let path = scriptsDir + "/io_write_test.lua"
+    runner.runScript(path, "")
+}
+
+@Test
+func testRedirectIoRead(): Unit {
+    // 1. 准备输入文件
+    let inputFile = "/tmp/input"
+    
+    // [修正点]：移除了不存在的 option 参数。
+    // File.writeTo 默认行为即为 CreateOrTruncate：
+    // 文件存在会截断（覆盖），不存在则创建。
+    File.writeTo(inputFile, "MockInputData".toArray())
+
+    // 2. 运行测试
+    let runner = LuaRunner(pathio: "/tmp")
+    let path = scriptsDir + "/io_read_test.lua"
+    
+    let res = runner.runScript(path, "")
+    @Expect(res, "MockInputData")
+}
+
+// ====================
+// 6. 错误码与回调
+// ====================
+
+@Test
+func testErrorCodesMapping(): Unit {
+    @Expect(LuaError.getErrorMessage(5001), "JSON file load failed")
+    @Expect(LuaError.getErrorMessage(5002), "Memory allocation failed")
+    @Expect(LuaError.getErrorMessage(5010), "Script internal error, check result for details")
+    @Expect(LuaError.getErrorMessage(9999), "Unknown error")
+}
+
+@Test
+func testDefaultIOCallback(): Unit {
+    let result = unsafe { defaultIO() }
+    @Expect(result, 0)
+}