diff --git a/pkg/fileutil/fileutil_test.go b/pkg/fileutil/fileutil_test.go
new file mode 100644
index 0000000..d00b585
--- /dev/null
+++ b/pkg/fileutil/fileutil_test.go
@@ -0,0 +1,136 @@
+package fileutil
+
+import (
+	"testing"
+)
+
+func TestShouldInclude(t *testing.T) {
+	tests := []struct {
+		name         string
+		path         string
+		excludePaths []string
+		includePaths []string
+		expected     bool
+	}{
+		{
+			name:         "no filters - should include",
+			path:         "/path/to/file.txt",
+			excludePaths: []string{},
+			includePaths: []string{},
+			expected:     true,
+		},
+		{
+			name:         "exclude pattern match",
+			path:         "/path/to/file.log",
+			excludePaths: []string{"*.log"},
+			includePaths: []string{},
+			expected:     false,
+		},
+		{
+			name:         "exclude directory pattern",
+			path:         "/path/node_modules/file.js",
+			excludePaths: []string{"node_modules"},
+			includePaths: []string{},
+			expected:     false,
+		},
+		{
+			name:         "exclude with wildcard directory",
+			path:         "/path/temp/file.txt",
+			excludePaths: []string{"temp/*"},
+			includePaths: []string{},
+			expected:     false,
+		},
+		{
+			name:         "include pattern match",
+			path:         "/path/to/file.go",
+			excludePaths: []string{},
+			includePaths: []string{"*.go"},
+			expected:     true,
+		},
+		{
+			name:         "include pattern no match",
+			path:         "/path/to/file.txt",
+			excludePaths: []string{},
+			includePaths: []string{"*.go"},
+			expected:     false,
+		},
+		{
+			name:         "exclude takes precedence",
+			path:         "/path/to/file.log",
+			excludePaths: []string{"*.log"},
+			includePaths: []string{"*.log"},
+			expected:     false,
+		},
+		{
+			name:         "multiple exclude patterns",
+			path:         "/path/to/file.tmp",
+			excludePaths: []string{"*.log", "*.tmp", "*.cache"},
+			includePaths: []string{},
+			expected:     false,
+		},
+		{
+			name:         "include directory pattern",
+			path:         "/path/src/main.go",
+			excludePaths: []string{},
+			includePaths: []string{"src/*"},
+			expected:     true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := ShouldInclude(tt.path, tt.excludePaths, tt.includePaths)
+			if result != tt.expected {
+				t.Errorf("ShouldInclude(%q, %v, %v) = %v; want %v",
+					tt.path, tt.excludePaths, tt.includePaths, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestFormatBytes(t *testing.T) {
+	tests := []struct {
+		name     string
+		bytes    int64
+		expected string
+	}{
+		{"zero bytes", 0, "0 B"},
+		{"bytes", 512, "512 B"},
+		{"kilobytes", 1024, "1.0 KB"},
+		{"megabytes", 1048576, "1.0 MB"},
+		{"gigabytes", 1073741824, "1.0 GB"},
+		{"terabytes", 1099511627776, "1.0 TB"},
+		{"mixed KB", 1536, "1.5 KB"},
+		{"mixed MB", 2621440, "2.5 MB"},
+		{"large value", 5368709120, "5.0 GB"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := FormatBytes(tt.bytes)
+			if result != tt.expected {
+				t.Errorf("FormatBytes(%d) = %q; want %q", tt.bytes, result, tt.expected)
+			}
+		})
+	}
+}
+
+func BenchmarkShouldInclude(b *testing.B) {
+	excludePaths := []string{"*.log", "*.tmp", "node_modules", ".git"}
+	includePaths := []string{"*.go", "*.md"}
+	path := "/path/to/some/file.go"
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		ShouldInclude(path, excludePaths, includePaths)
+	}
+}
+
+func BenchmarkFormatBytes(b *testing.B) {
+	bytes := int64(1073741824) // 1 GB
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		FormatBytes(bytes)
+	}
+}