Add table-driven test example

projects/interfaces/buffer_table_test.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestOurByteBuffer_Table(t *testing.T) {
+	for name, tc := range map[string]struct {
+		initialContent string
+		operations     []operation
+	}{
+		"read_initial_bytes": {
+			initialContent: "hello",
+			operations: []operation{
+				&bytesOperation{
+					wantValue: "hello",
+				},
+			},
+		},
+		"subsequent_writes_are_appended": {
+			initialContent: "hello",
+			operations: []operation{
+				&writeOperation{
+					value: " world",
+				},
+				&bytesOperation{
+					wantValue: "hello world",
+				},
+			},
+		},
+		"read_oversized_slice": {
+			initialContent: "hello world",
+			operations: []operation{
+				&readOperation{
+					bufferSize: 50,
+					wantValue:  "hello world",
+				},
+			},
+		},
+		"read_undersized_slices": {
+			initialContent: "hello world",
+			operations: []operation{
+				&readOperation{
+					bufferSize: 6,
+					wantValue:  "hello ",
+				},
+				&readOperation{
+					bufferSize: 5,
+					wantValue:  "world",
+				},
+			},
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			b := NewBufferString(tc.initialContent)
+			for _, operation := range tc.operations {
+				operation.Do(t, &b)
+			}
+		})
+	}
+}
+
+type operation interface {
+	Do(t *testing.T, b *OurByteBuffer)
+}
+
+type readOperation struct {
+	bufferSize int
+	wantValue  string
+}
+
+func (o *readOperation) Do(t *testing.T, b *OurByteBuffer) {
+	t.Helper()
+	buf := make([]byte, o.bufferSize)
+	n, err := b.Read(buf)
+	require.NoError(t, err)
+	require.Equal(t, len(o.wantValue), n)
+	require.Equal(t, o.wantValue, string(buf[:n]))
+}
+
+type writeOperation struct {
+	value string
+}
+
+func (o *writeOperation) Do(t *testing.T, b *OurByteBuffer) {
+	t.Helper()
+	n, err := b.Write([]byte(o.value))
+	require.NoError(t, err)
+	require.Equal(t, len(o.value), n)
+}
+
+type bytesOperation struct {
+	wantValue string
+}
+
+func (o *bytesOperation) Do(t *testing.T, b *OurByteBuffer) {
+	t.Helper()
+	got := string(b.Bytes())
+	require.Equal(t, o.wantValue, got)
+}