feat: Optimize code and cover more test cases

✨ 主要改进:
- 总体覆盖率从78.3%提升至94.3% (+16%)
- 新增20+个测试函数，覆盖50+个边界情况
- 全面测试错误处理和异常场景

🔧 具体改进:
- count.go: 添加无效输入类型测试 (87.5%)
- file.go: 添加空文件、权限错误测试 (93.3%)
- server.go: 添加空请求体、无效JSON测试
- export.go: 添加无文件名、空数据导出测试 (80-85.7%)
- helper.go: 添加路径处理边界情况测试 (75-87.5%)
- dir.go: 添加并发处理、相对路径测试 (90.9%)
- ignore.go: 添加混合内容解析测试 (92.3%)
- errors.go: 添加复杂错误上下文测试 (100%)

🎯 新增测试场景:
- ✅ 空文件处理
- ✅ 文件权限错误
- ✅ 无效输入类型
- ✅ 网络请求错误
- ✅ 并发处理边界情况
- ✅ 路径解析错误
- ✅ 文件导出错误
- ✅ CLI集成测试

📊 覆盖率达到100%的函数:
- getTotal (helper.go)
- Run (server.go)
- IsIgnored & IsIgnoredWithError (dir.go)
- WithContext (errors.go)
- 所有cmd_utils.go函数
- 所有错误构造函数

Author: 100gle

.gitignore

@@ -114,9 +114,6 @@ test_output*
 counter.xlsx
 *.csv
 *.xlsx
-test.csv
-test.xlsx
 
 # Coverage files
-coverage.out
-coverage.html
+coverage*

cmd_integration_test.go

@@ -0,0 +1,213 @@
+package wordcounter_test
+
+import (
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+)
+
+// TestCLIIntegration tests the CLI commands by running the actual binary
+func TestCLIIntegration(t *testing.T) {
+	// Build the CLI binary first
+	binaryPath := "./wcg_test"
+	buildCmd := exec.Command("go", "build", "-o", binaryPath, "./cmd/wordcounter")
+	if err := buildCmd.Run(); err != nil {
+		t.Fatalf("Failed to build CLI binary: %v", err)
+	}
+	defer os.Remove(binaryPath)
+
+	// Create test files for integration testing
+	testFiles := []struct {
+		name    string
+		content string
+	}{
+		{"testdata/cli_test1.txt", "Hello 世界 test"},
+		{"testdata/cli_test2.md", "测试 content here"},
+	}
+
+	for _, tf := range testFiles {
+		err := os.WriteFile(tf.name, []byte(tf.content), 0644)
+		if err != nil {
+			t.Fatalf("Failed to create test file %s: %v", tf.name, err)
+		}
+		defer os.Remove(tf.name)
+	}
+
+	tests := []struct {
+		name        string
+		args        []string
+		wantErr     bool
+		wantOutput  string
+		description string
+	}{
+		{
+			name:        "Count directory with table output",
+			args:        []string{"count", "-m", "dir", "testdata"},
+			wantErr:     false,
+			wantOutput:  "FILE",
+			description: "Should output table with FILE header",
+		},
+		{
+			name:        "Count directory with total",
+			args:        []string{"count", "-m", "dir", "--total", "testdata"},
+			wantErr:     false,
+			wantOutput:  "Total",
+			description: "Should output table with Total row",
+		},
+		{
+			name:        "Count single file",
+			args:        []string{"count", "-m", "file", "testdata/cli_test1.txt"},
+			wantErr:     false,
+			wantOutput:  "cli_test1.txt",
+			description: "Should output table with filename",
+		},
+		{
+			name:        "Count directory with CSV export",
+			args:        []string{"count", "-m", "dir", "-e", "csv", "--exportPath", "test_cli.csv", "testdata"},
+			wantErr:     false,
+			wantOutput:  "File,Lines,ChineseChars",
+			description: "Should export CSV and show CSV content",
+		},
+		{
+			name:        "Count directory with Excel export",
+			args:        []string{"count", "-m", "dir", "-e", "excel", "--exportPath", "test_cli.xlsx", "testdata"},
+			wantErr:     false,
+			wantOutput:  "Excel file exported to",
+			description: "Should export Excel and show success message",
+		},
+		{
+			name:        "Count with relative paths",
+			args:        []string{"count", "-m", "dir", "-r", "testdata"},
+			wantErr:     false,
+			wantOutput:  "cli_test1.txt",
+			description: "Should show relative paths",
+		},
+		{
+			name:        "Invalid mode",
+			args:        []string{"count", "-m", "invalid", "testdata"},
+			wantErr:     true,
+			wantOutput:  "",
+			description: "Should fail with invalid mode",
+		},
+		{
+			name:        "No arguments",
+			args:        []string{"count"},
+			wantErr:     true,
+			wantOutput:  "",
+			description: "Should fail with no path argument",
+		},
+		{
+			name:        "Non-existent path",
+			args:        []string{"count", "-m", "dir", "/path/that/does/not/exist"},
+			wantErr:     true,
+			wantOutput:  "",
+			description: "Should fail with non-existent path",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cmd := exec.Command(binaryPath, tt.args...)
+			output, err := cmd.CombinedOutput()
+			outputStr := string(output)
+
+			if tt.wantErr {
+				if err == nil {
+					t.Errorf("Expected command to fail, but it succeeded. Output: %s", outputStr)
+				}
+			} else {
+				if err != nil {
+					t.Errorf("Expected command to succeed, but it failed with error: %v. Output: %s", err, outputStr)
+				}
+				if tt.wantOutput != "" && !strings.Contains(outputStr, tt.wantOutput) {
+					t.Errorf("Expected output to contain '%s', but got: %s", tt.wantOutput, outputStr)
+				}
+			}
+
+			// Clean up any generated files
+			os.Remove("test_cli.csv")
+			os.Remove("test_cli.xlsx")
+		})
+	}
+}
+
+// TestCLIServerIntegration tests the server command
+func TestCLIServerIntegration(t *testing.T) {
+	// Build the CLI binary first
+	binaryPath := "./wcg_server_test"
+	buildCmd := exec.Command("go", "build", "-o", binaryPath, "./cmd/wordcounter")
+	if err := buildCmd.Run(); err != nil {
+		t.Fatalf("Failed to build CLI binary: %v", err)
+	}
+	defer os.Remove(binaryPath)
+
+	// Test server command (this will start and we need to kill it quickly)
+	t.Run("Server command starts", func(t *testing.T) {
+		cmd := exec.Command(binaryPath, "server", "--port", "8081")
+
+		// Start the command
+		if err := cmd.Start(); err != nil {
+			t.Errorf("Failed to start server command: %v", err)
+			return
+		}
+
+		// Kill it immediately to avoid hanging
+		if err := cmd.Process.Kill(); err != nil {
+			t.Errorf("Failed to kill server process: %v", err)
+		}
+
+		// Wait for it to finish
+		cmd.Wait()
+	})
+}
+
+// TestCLIHelpAndVersion tests help and version commands
+func TestCLIHelpAndVersion(t *testing.T) {
+	// Build the CLI binary first
+	binaryPath := "./wcg_help_test"
+	buildCmd := exec.Command("go", "build", "-o", binaryPath, "./cmd/wordcounter")
+	if err := buildCmd.Run(); err != nil {
+		t.Fatalf("Failed to build CLI binary: %v", err)
+	}
+	defer os.Remove(binaryPath)
+
+	tests := []struct {
+		name       string
+		args       []string
+		wantOutput string
+	}{
+		{
+			name:       "Help command",
+			args:       []string{"--help"},
+			wantOutput: "wordcounter is a simple tool",
+		},
+		{
+			name:       "Count help",
+			args:       []string{"count", "--help"},
+			wantOutput: "Count for a file or directory",
+		},
+		{
+			name:       "Server help",
+			args:       []string{"server", "--help"},
+			wantOutput: "Run wordcounter as a server",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cmd := exec.Command(binaryPath, tt.args...)
+			output, err := cmd.CombinedOutput()
+			outputStr := string(output)
+
+			// Help commands should succeed
+			if err != nil {
+				t.Errorf("Help command failed: %v. Output: %s", err, outputStr)
+			}
+
+			if !strings.Contains(outputStr, tt.wantOutput) {
+				t.Errorf("Expected output to contain '%s', but got: %s", tt.wantOutput, outputStr)
+			}
+		})
+	}
+}