diff --git a/internal/fetcher/fetcher_test.go b/internal/fetcher/fetcher_test.go
new file mode 100644
index 0000000..be3ec5d
--- /dev/null
+++ b/internal/fetcher/fetcher_test.go
@@ -0,0 +1,189 @@
+package fetcher
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestIsValidArchiveURL(t *testing.T) {
+	tests := []struct {
+		name     string
+		url      string
+		expected bool
+	}{
+		{"ZIP URL", "https://example.com/archive.zip", true},
+		{"TAR URL", "https://example.com/archive.tar", true},
+		{"TAR.GZ URL", "https://example.com/archive.tar.gz", true},
+		{"TGZ URL", "https://example.com/archive.tgz", true},
+		{"GZIP URL", "https://example.com/file.gz", true},
+		{"RAR URL", "https://example.com/archive.rar", true},
+		{"Invalid URL", "https://example.com/file.txt", false},
+		{"No extension", "https://example.com/file", false},
+		{"Invalid format", "not a url", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := IsValidArchiveURL(tt.url)
+			if result != tt.expected {
+				t.Errorf("IsValidArchiveURL(%q) = %v; want %v", tt.url, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestGetFilenameFromURL(t *testing.T) {
+	tests := []struct {
+		name        string
+		url         string
+		expected    string
+		expectError bool
+	}{
+		{"Simple filename", "https://example.com/archive.zip", "archive.zip", false},
+		{"Path with directories", "https://example.com/path/to/file.tar.gz", "file.tar.gz", false},
+		{"Query parameters", "https://example.com/file.zip?download=true", "file.zip", false},
+		{"No filename", "https://example.com/", "", true},
+		{"Relative path treated as filename", "not a url", "not a url", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := GetFilenameFromURL(tt.url)
+			if tt.expectError {
+				if err == nil {
+					t.Errorf("Expected error for %q, got nil", tt.url)
+				}
+			} else {
+				if err != nil {
+					t.Errorf("Unexpected error for %q: %v", tt.url, err)
+				}
+				if result != tt.expected {
+					t.Errorf("GetFilenameFromURL(%q) = %q; want %q", tt.url, result, tt.expected)
+				}
+			}
+		})
+	}
+}
+
+func TestDownloadFile(t *testing.T) {
+	// Create a test server
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Length", "13")
+		w.Write([]byte("test content!"))
+	}))
+	defer server.Close()
+
+	// Create temp directory
+	tempDir := t.TempDir()
+	outputFile := filepath.Join(tempDir, "downloaded.txt")
+
+	// Test download
+	err := downloadFile(outputFile, server.URL)
+	if err != nil {
+		t.Fatalf("Failed to download file: %v", err)
+	}
+
+	// Verify file exists
+	if _, err := os.Stat(outputFile); os.IsNotExist(err) {
+		t.Error("Downloaded file does not exist")
+	}
+
+	// Verify content
+	content, err := os.ReadFile(outputFile)
+	if err != nil {
+		t.Fatalf("Failed to read downloaded file: %v", err)
+	}
+
+	expected := "test content!"
+	if string(content) != expected {
+		t.Errorf("Downloaded content = %q; want %q", string(content), expected)
+	}
+}
+
+func TestDownloadFileNotFound(t *testing.T) {
+	// Create a test server that returns 404
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer server.Close()
+
+	tempDir := t.TempDir()
+	outputFile := filepath.Join(tempDir, "downloaded.txt")
+
+	err := downloadFile(outputFile, server.URL)
+	if err == nil {
+		t.Error("Expected error for 404 response, got nil")
+	}
+}
+
+func TestDownloadFileInvalidURL(t *testing.T) {
+	tempDir := t.TempDir()
+	outputFile := filepath.Join(tempDir, "downloaded.txt")
+
+	err := downloadFile(outputFile, "http://invalid-url-that-does-not-exist-12345.com")
+	if err == nil {
+		t.Error("Expected error for invalid URL, got nil")
+	}
+}
+
+func TestFetchAndExtractInvalidURL(t *testing.T) {
+	err := FetchAndExtract("not a url", "/tmp/output", false, true)
+	if err == nil {
+		t.Error("Expected error for invalid URL, got nil")
+	}
+}
+
+func TestFetchAndExtractNonHTTP(t *testing.T) {
+	err := FetchAndExtract("ftp://example.com/file.zip", "/tmp/output", false, true)
+	if err == nil {
+		t.Error("Expected error for non-HTTP URL, got nil")
+	}
+
+	expectedMsg := "only HTTP and HTTPS URLs are supported"
+	if err != nil && err.Error() != expectedMsg {
+		t.Errorf("Expected error message %q, got %q", expectedMsg, err.Error())
+	}
+}
+
+func TestProgressReader(t *testing.T) {
+	// Create a test reader
+	data := []byte("test data for progress reader")
+	pr := &progressReader{
+		reader:        nil, // We'll test the struct directly
+		total:         int64(len(data)),
+		downloaded:    0,
+		lastPrintSize: 0,
+	}
+
+	// Test initial state
+	if pr.downloaded != 0 {
+		t.Errorf("Initial downloaded = %d; want 0", pr.downloaded)
+	}
+
+	if pr.total != int64(len(data)) {
+		t.Errorf("Total = %d; want %d", pr.total, len(data))
+	}
+}
+
+func TestFetchAndExtractInvalidDestination(t *testing.T) {
+	// Create a test server with a valid ZIP
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Length", "4")
+		w.Write([]byte("test"))
+	}))
+	defer server.Close()
+
+	// Try to extract to an invalid destination (file instead of directory)
+	tempDir := t.TempDir()
+	invalidDest := filepath.Join(tempDir, "file.txt")
+	os.WriteFile(invalidDest, []byte("test"), 0644)
+
+	err := FetchAndExtract(server.URL+"/test.zip", invalidDest, false, true)
+	// This should fail during extraction or detection
+	if err == nil {
+		t.Log("Note: This test may pass if the downloaded content is not a valid archive")
+	}
+}