internal/download: improve era file status messages

internal/download/download.go

@@ -179,13 +179,22 @@ func (db *ChecksumDB) DownloadFile(url, dstPath string) error {
 	if hash == "" {
 		return fmt.Errorf("no known hash for file %q", basename)
 	}
-	// Shortcut if already downloaded.
-	if verifyHash(dstPath, hash) == nil {
+
+	// Check if file exists and verify its hash
+	if err := verifyHash(dstPath, hash); err != nil {
+		// Check if the error is due to file not existing
+		if os.IsNotExist(err) {
+			fmt.Printf("%s not found, downloading...\n", dstPath)
+		} else {
+			// File exists but hash doesn't match
+			fmt.Printf("%s is stale (hash mismatch)\n", dstPath)
+		}
+	} else {
+		// File exists and hash matches
 		fmt.Printf("%s is up-to-date\n", dstPath)
 		return nil
 	}
 
-	fmt.Printf("%s is stale\n", dstPath)
 	fmt.Printf("downloading from %s\n", url)
 	resp, err := http.Get(url)
 	if err != nil {

internal/download/download_test.go

@@ -0,0 +1,171 @@
+// Copyright 2024 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package download
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestDownloadFileMessages(t *testing.T) {
+	// Create a test server
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("test file content"))
+	}))
+	defer server.Close()
+
+	// Create test checksum database
+	testContent := "test file content"
+	hash := sha256.Sum256([]byte(testContent))
+	expectedHash := hex.EncodeToString(hash[:])
+
+	checksumData := fmt.Sprintf("# %s\n%s testfile.txt\n", server.URL, expectedHash)
+	csdb, err := ParseChecksums([]byte(checksumData))
+	if err != nil {
+		t.Fatalf("Failed to parse checksums: %v", err)
+	}
+
+	tempDir := t.TempDir()
+	testFile := filepath.Join(tempDir, "testfile.txt")
+
+	tests := []struct {
+		name           string
+		setupFile      func() error
+		expectedOutput string
+	}{
+		{
+			name:           "file not found",
+			setupFile:      func() error { return nil }, // Don't create file
+			expectedOutput: "not found, downloading...",
+		},
+		{
+			name: "file exists with correct hash",
+			setupFile: func() error {
+				return os.WriteFile(testFile, []byte(testContent), 0644)
+			},
+			expectedOutput: "is up-to-date",
+		},
+		{
+			name: "file exists with wrong hash",
+			setupFile: func() error {
+				return os.WriteFile(testFile, []byte("wrong content"), 0644)
+			},
+			expectedOutput: "is stale (hash mismatch)",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Clean up from previous test
+			os.Remove(testFile)
+
+			// Setup test file if needed
+			if err := tt.setupFile(); err != nil {
+				t.Fatalf("Failed to setup test file: %v", err)
+			}
+
+			// Capture output
+			var buf bytes.Buffer
+			originalStdout := os.Stdout
+			r, w, _ := os.Pipe()
+			os.Stdout = w
+
+			// Run the download
+			url := server.URL + "/testfile.txt"
+			err := csdb.DownloadFile(url, testFile)
+
+			// Restore stdout and read captured output
+			w.Close()
+			os.Stdout = originalStdout
+			io.Copy(&buf, r)
+			output := buf.String()
+
+			// For "up-to-date" case, we expect no error and no download
+			if tt.name == "file exists with correct hash" {
+				if err != nil {
+					t.Errorf("Expected no error for up-to-date file, got: %v", err)
+				}
+				if !strings.Contains(output, tt.expectedOutput) {
+					t.Errorf("Expected output to contain %q, got: %q", tt.expectedOutput, output)
+				}
+				return
+			}
+
+			// For other cases, we expect successful download
+			if err != nil {
+				t.Errorf("Download failed: %v", err)
+			}
+
+			if !strings.Contains(output, tt.expectedOutput) {
+				t.Errorf("Expected output to contain %q, got: %q", tt.expectedOutput, output)
+			}
+
+			// Verify file was downloaded correctly
+			content, err := os.ReadFile(testFile)
+			if err != nil {
+				t.Errorf("Failed to read downloaded file: %v", err)
+			}
+			if string(content) != testContent {
+				t.Errorf("Downloaded content mismatch: got %q, want %q", string(content), testContent)
+			}
+		})
+	}
+}
+
+func TestVerifyHashErrorTypes(t *testing.T) {
+	tempDir := t.TempDir()
+
+	// Test file not found
+	nonExistentFile := filepath.Join(tempDir, "nonexistent.txt")
+	err := verifyHash(nonExistentFile, "somehash")
+	if !os.IsNotExist(err) {
+		t.Errorf("Expected os.IsNotExist error for non-existent file, got: %v", err)
+	}
+
+	// Test hash mismatch
+	testFile := filepath.Join(tempDir, "test.txt")
+	content := "test content"
+	if err := os.WriteFile(testFile, []byte(content), 0644); err != nil {
+		t.Fatalf("Failed to create test file: %v", err)
+	}
+
+	wrongHash := "wronghash"
+	err = verifyHash(testFile, wrongHash)
+	if err == nil {
+		t.Error("Expected hash mismatch error, got nil")
+	}
+	if os.IsNotExist(err) {
+		t.Error("Hash mismatch should not be treated as file not found")
+	}
+
+	// Test correct hash
+	hash := sha256.Sum256([]byte(content))
+	correctHash := hex.EncodeToString(hash[:])
+	err = verifyHash(testFile, correctHash)
+	if err != nil {
+		t.Errorf("Expected no error for correct hash, got: %v", err)
+	}
+}