Add tests for the actual usability of the Decodable and Encodable interfaces

1 files changed, 115 insertions, 0 deletions

diff --git a/methods_test.go b/methods_test.go
new file mode 100644
index 0000000..8280a94
--- /dev/null
+++ b/methods_test.go
@@ -0,0 +1,115 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package lowmemjson_test
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"git.lukeshu.com/go/lowmemjson"
+)
+
+type SumRun struct {
+	ChecksumSize int   `json:",omitempty"`
+	Addr         int64 `json:",omitempty"`
+	Sums         string
+}
+
+type SumRunWithGaps struct {
+	Addr int64
+	Size int64
+	Runs []SumRun
+}
+
+func (sg SumRunWithGaps) EncodeJSON(w io.Writer) error {
+	if _, err := fmt.Fprintf(w, `{"Addr":%d,"Size":%d,"Runs":[`, sg.Addr, sg.Size); err != nil {
+		return err
+	}
+	cur := sg.Addr
+	for i, run := range sg.Runs {
+		if i > 0 {
+			if _, err := w.Write([]byte{','}); err != nil {
+				return err
+			}
+		}
+		if run.Addr > cur {
+			if _, err := fmt.Fprintf(w, `{"Gap":%d},`, run.Addr-cur); err != nil {
+				return err
+			}
+		}
+		if err := lowmemjson.Encode(w, run); err != nil {
+			return err
+		}
+	}
+	end := sg.Addr + sg.Size
+	switch {
+	case end < cur:
+		return fmt.Errorf("invalid %T: addr went backwards: %v < %v", sg, end, cur)
+	case end > cur:
+		if _, err := fmt.Fprintf(w, `,{"Gap":%d}`, end-cur); err != nil {
+			return err
+		}
+	}
+	if _, err := w.Write([]byte("]}")); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (sg *SumRunWithGaps) DecodeJSON(r io.RuneScanner) error {
+	*sg = SumRunWithGaps{}
+	var name string
+	return lowmemjson.DecodeObject(r,
+		func(r io.RuneScanner) error {
+			return lowmemjson.Decode(r, &name)
+		},
+		func(r io.RuneScanner) error {
+			switch name {
+			case "Addr":
+				return lowmemjson.Decode(r, &sg.Addr)
+			case "Size":
+				return lowmemjson.Decode(r, &sg.Size)
+			case "Runs":
+				return lowmemjson.DecodeArray(r, func(r io.RuneScanner) error {
+					var run SumRun
+					if err := lowmemjson.Decode(r, &run); err != nil {
+						return err
+					}
+					if run.ChecksumSize > 0 {
+						sg.Runs = append(sg.Runs, run)
+					}
+					return nil
+				})
+			default:
+				return fmt.Errorf("unknown key %q", name)
+			}
+		})
+}
+
+func TestMethods(t *testing.T) {
+	in := SumRunWithGaps{
+		Addr: 13631488,
+		Size: 416033783808,
+		Runs: []SumRun{
+			{
+				ChecksumSize: 4,
+				Addr:         1095761920,
+				Sums:         "c160817cb5c72bbbe",
+			},
+		},
+	}
+	var buf bytes.Buffer
+	assert.NoError(t, lowmemjson.Encode(&buf, in))
+	assert.Equal(t,
+		`{"Addr":13631488,"Size":416033783808,"Runs":[{"Gap":1082130432},{"ChecksumSize":4,"Addr":1095761920,"Sums":"c160817cb5c72bbbe"},{"Gap":416033783808}]}`,
+		buf.String())
+	var out SumRunWithGaps
+	assert.NoError(t, lowmemjson.Decode(&buf, &out))
+	assert.Equal(t, in, out)
+}