Count every file of each version in secret info's Total Size (closes #147)

Total Size added up each version's data.age and metadata.age, but a
version keeps its value in value.age, so no secret's value was counted.
It now adds up every file in each version directory: the value, the
metadata and the version's two keys, as the plan on the issue decided.
A version directory that cannot be read adds nothing and gets a warning
naming it.

The new tests add a 10000-byte secret and check that the total grows by
at least that much, and check the warning for a version directory that
cannot be read.

Model: opus-5-5

internal/cli/info_test.go

@@ -0,0 +1,64 @@
+package cli_test
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/json"
+	"testing"
+
+	"github.com/awnumar/memguard"
+	"github.com/spf13/afero"
+	"github.com/spf13/cobra"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/secret/internal/cli"
+	"sneak.berlin/go/secret/internal/vault"
+)
+
+// TestInfoTotalSizeCountsSecretValues is a regression test for
+// https://git.eeqj.de/sneak/secret/issues/147, where the total size shown by
+// `secret info` left out every secret's value. Adding a secret must make it
+// grow by at least the size of the value.
+func TestInfoTotalSizeCountsSecretValues(t *testing.T) {
+	t.Parallel()
+
+	const valueSize = 10000
+
+	fs := afero.NewMemMapFs()
+
+	vlt, err := vault.CreateVault(fs, testStateDir, "default",
+		testMnemonicBuffer(t), nil)
+	require.NoError(t, err)
+
+	before := infoTotalSize(t, fs)
+
+	valueBytes := make([]byte, valueSize)
+	_, err = rand.Read(valueBytes)
+	require.NoError(t, err)
+
+	value := memguard.NewBufferFromBytes(valueBytes)
+	defer value.Destroy()
+
+	require.NoError(t, vlt.AddSecret("s1", value, false))
+
+	after := infoTotalSize(t, fs)
+	require.GreaterOrEqual(t, after-before, int64(valueSize))
+}
+
+// infoTotalSize returns the total size that `secret info --json` reports for
+// the state directory on fs.
+func infoTotalSize(t *testing.T, fs afero.Fs) int64 {
+	t.Helper()
+
+	var out bytes.Buffer
+
+	cmd := &cobra.Command{}
+	cmd.SetOut(&out)
+
+	err := cli.NewCLIInstanceWithStateDir(fs, testStateDir).Info(cmd, true)
+	require.NoError(t, err)
+
+	var info cli.InfoOutput
+	require.NoError(t, json.Unmarshal(out.Bytes(), &info))
+
+	return info.TotalSize
+}