add a basic test for Batch

batch_test.go

+package format
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	cid "github.com/ipfs/go-cid"
+)
+
+// Test dag
+type testDag struct {
+	mu    sync.Mutex
+	nodes map[string]Node
+}
+
+func newTestDag() *testDag {
+	return &testDag{nodes: make(map[string]Node)}
+}
+
+func (d *testDag) Get(ctx context.Context, cid *cid.Cid) (Node, error) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	if n, ok := d.nodes[cid.KeyString()]; ok {
+		return n, nil
+	}
+	return nil, ErrNotFound
+}
+
+func (d *testDag) GetMany(ctx context.Context, cids []*cid.Cid) <-chan *NodeOption {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	out := make(chan *NodeOption, len(cids))
+	for _, c := range cids {
+		if n, ok := d.nodes[c.KeyString()]; ok {
+			out <- &NodeOption{Node: n}
+		} else {
+			out <- &NodeOption{Err: ErrNotFound}
+		}
+	}
+	return out
+}
+
+func (d *testDag) Add(node Node) (*cid.Cid, error) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	c := node.Cid()
+	d.nodes[c.KeyString()] = node
+	return c, nil
+}
+
+func (d *testDag) AddMany(nodes []Node) ([]*cid.Cid, error) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	cids := make([]*cid.Cid, len(nodes))
+	for i, n := range nodes {
+		c := n.Cid()
+		d.nodes[c.KeyString()] = n
+		cids[i] = c
+	}
+	return cids, nil
+}
+
+func (d *testDag) Remove(c *cid.Cid) error {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	key := c.KeyString()
+	if _, exists := d.nodes[key]; !exists {
+		return ErrNotFound
+	}
+	delete(d.nodes, key)
+	return nil
+}
+
+var _ DAGService = new(testDag)
+
+func TestBatch(t *testing.T) {
+	d := newTestDag()
+	b := NewBatch(d)
+	for i := 0; i < 1000; i++ {
+		// It would be great if we could use *many* different nodes here
+		// but we can't add any dependencies and I don't feel like adding
+		// any more testing code.
+		if _, err := b.Add(new(EmptyNode)); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := b.Commit(); err != nil {
+		t.Fatal(err)
+	}
+
+	n, err := d.Get(context.Background(), new(EmptyNode).Cid())
+	if err != nil {
+		t.Fatal(err)
+	}
+	switch n.(type) {
+	case *EmptyNode:
+	default:
+		t.Fatal("expected the node to exist in the dag")
+	}
+
+	if len(d.nodes) != 1 {
+		t.Fatal("should have one node")
+	}
+}