1.0 quality polish — code review, tests, bug fixes, documentation (#32)

Comprehensive quality pass targeting 1.0 release:

- Code review and refactoring
- Fix open bugs (#14, #16, #23)
- Expand test coverage
- Lint clean
- README update with build instructions (#9)
- Documentation improvements

Branched from `next` (active dev branch).

Reviewed-on: #32
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>

internal/cli/export_test.go

@@ -0,0 +1,137 @@
+package cli
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/mfer/mfer"
+)
+
+// buildTestManifest creates a manifest from in-memory files and returns its bytes.
+func buildTestManifest(t *testing.T, files map[string][]byte) []byte {
+	t.Helper()
+	sourceFs := afero.NewMemMapFs()
+	for path, content := range files {
+		require.NoError(t, sourceFs.MkdirAll("/", 0o755))
+		require.NoError(t, afero.WriteFile(sourceFs, "/"+path, content, 0o644))
+	}
+
+	opts := &mfer.ScannerOptions{Fs: sourceFs}
+	s := mfer.NewScannerWithOptions(opts)
+	require.NoError(t, s.EnumerateFS(sourceFs, "/", nil))
+
+	var buf bytes.Buffer
+	require.NoError(t, s.ToManifest(context.Background(), &buf, nil))
+	return buf.Bytes()
+}
+
+func TestExportManifestOperation(t *testing.T) {
+	testFiles := map[string][]byte{
+		"hello.txt":    []byte("Hello, World!"),
+		"sub/file.txt": []byte("nested content"),
+	}
+	manifestData := buildTestManifest(t, testFiles)
+
+	// Write manifest to memfs
+	fs := afero.NewMemMapFs()
+	require.NoError(t, afero.WriteFile(fs, "/test.mf", manifestData, 0o644))
+
+	var stdout, stderr bytes.Buffer
+	exitCode := RunWithOptions(&RunOptions{
+		Appname: "mfer",
+		Args:    []string{"mfer", "export", "/test.mf"},
+		Stdin:   &bytes.Buffer{},
+		Stdout:  &stdout,
+		Stderr:  &stderr,
+		Fs:      fs,
+	})
+
+	require.Equal(t, 0, exitCode, "stderr: %s", stderr.String())
+
+	var entries []ExportEntry
+	require.NoError(t, json.Unmarshal(stdout.Bytes(), &entries))
+	assert.Len(t, entries, 2)
+
+	// Verify entries have expected fields
+	pathSet := make(map[string]bool)
+	for _, e := range entries {
+		pathSet[e.Path] = true
+		assert.NotEmpty(t, e.Hashes, "entry %s should have hashes", e.Path)
+		assert.Greater(t, e.Size, int64(0), "entry %s should have positive size", e.Path)
+	}
+	assert.True(t, pathSet["hello.txt"])
+	assert.True(t, pathSet["sub/file.txt"])
+}
+
+func TestExportFromHTTPURL(t *testing.T) {
+	testFiles := map[string][]byte{
+		"a.txt": []byte("aaa"),
+	}
+	manifestData := buildTestManifest(t, testFiles)
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/octet-stream")
+		_, _ = w.Write(manifestData)
+	}))
+	defer server.Close()
+
+	var stdout, stderr bytes.Buffer
+	exitCode := RunWithOptions(&RunOptions{
+		Appname: "mfer",
+		Args:    []string{"mfer", "export", server.URL + "/index.mf"},
+		Stdin:   &bytes.Buffer{},
+		Stdout:  &stdout,
+		Stderr:  &stderr,
+		Fs:      afero.NewMemMapFs(),
+	})
+
+	require.Equal(t, 0, exitCode, "stderr: %s", stderr.String())
+
+	var entries []ExportEntry
+	require.NoError(t, json.Unmarshal(stdout.Bytes(), &entries))
+	assert.Len(t, entries, 1)
+	assert.Equal(t, "a.txt", entries[0].Path)
+}
+
+func TestListFromHTTPURL(t *testing.T) {
+	testFiles := map[string][]byte{
+		"one.txt": []byte("1"),
+		"two.txt": []byte("22"),
+	}
+	manifestData := buildTestManifest(t, testFiles)
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write(manifestData)
+	}))
+	defer server.Close()
+
+	var stdout, stderr bytes.Buffer
+	exitCode := RunWithOptions(&RunOptions{
+		Appname: "mfer",
+		Args:    []string{"mfer", "list", server.URL + "/index.mf"},
+		Stdin:   &bytes.Buffer{},
+		Stdout:  &stdout,
+		Stderr:  &stderr,
+		Fs:      afero.NewMemMapFs(),
+	})
+
+	require.Equal(t, 0, exitCode, "stderr: %s", stderr.String())
+	output := stdout.String()
+	assert.Contains(t, output, "one.txt")
+	assert.Contains(t, output, "two.txt")
+}
+
+func TestIsHTTPURL(t *testing.T) {
+	assert.True(t, isHTTPURL("http://example.com/manifest.mf"))
+	assert.True(t, isHTTPURL("https://example.com/manifest.mf"))
+	assert.False(t, isHTTPURL("/local/path.mf"))
+	assert.False(t, isHTTPURL("relative/path.mf"))
+	assert.False(t, isHTTPURL("ftp://example.com/file"))
+}