Function TestEncoderDecoder_Roundtrip

internal/copyover/copyover_test.go:84–131

TestEncoderDecoder_Roundtrip verifies that the wire format preserves values exactly across multiple sections, including non-ASCII content. It goes through Save/Restore since the encoder and decoder are only well-formed as a pair produced by Save (which writes the section count header).

(t *testing.T)

// Save/Restore since the encoder and decoder are only well-formed as a pair
// produced by Save (which writes the section count header).
func TestEncoderDecoder_Roundtrip(t *testing.T) {
	type payload struct {
		Value string `json:"value"`
		Count int    `json:"count"`
	}

	cases := []struct {
		name string
		data payload
	}{
		{"section-a", payload{"hello", 1}},
		{"section-b", payload{"world", 42}},
		{"unicode", payload{"日本語テスト", 0}},
	}

	// Build contributors that hold the expected payloads.
	type structContributor struct {
		name     string
		data     payload
		restored payload
	}
	contribs := make([]*structContributor, len(cases))
	for i, tc := range cases {
		contribs[i] = &structContributor{name: tc.name, data: tc.data}
	}

	copyover.ResetRegistry()
	for _, c := range contribs {
		c := c
		copyover.Register(copyover.FuncContributor(
			c.name,
			func(enc *copyover.Encoder) error { return enc.WriteSection(c.name, c.data) },
			func(dec *copyover.Decoder) error { return dec.ReadSection(c.name, &c.restored) },
		))
	}

	r, w, err := os.Pipe()
	require.NoError(t, err)
	require.NoError(t, copyover.Save(w))
	w.Close()

	require.NoError(t, copyover.Restore(int(r.Fd())))
	r.Close()

	for _, c := range contribs {
		assert.Equal(t, c.data, c.restored, "section %q", c.name)
	}
}

// TestDecoder_MissingSection verifies that reading a section that was never
// written returns an error rather than silently producing a zero value.