feat(args): export fluent builder

pkg/args/builder.go

@@ -0,0 +1,71 @@
+package args
+
+import (
+	"errors"
+
+	"github.com/ipld/go-ipld-prime"
+)
+
+// Builder allows the fluid construction of an Args.
+type Builder struct {
+	args *Args
+	errs error
+}
+
+// NewBuilder returns a Builder which will assemble the Args.
+func NewBuilder() *Builder {
+	return &Builder{
+		args: New(),
+	}
+}
+
+// Add inserts a new key/val into the Args being assembled while collecting
+// any errors caused by duplicate keys.
+func (b *Builder) Add(key string, val any) *Builder {
+	b.errs = errors.Join(b.errs, b.args.Add(key, val))
+
+	return b
+}
+
+// Build returns the assembled Args or an error containing a list of
+// errors encountered while trying to build the Args.
+func (b *Builder) Build() (*Args, error) {
+	if b.errs != nil {
+		return nil, b.errs
+	}
+
+	return b.args, nil
+}
+
+// BuildIPLD is the same as Build except it takes the additional step of
+// converting the Args to an ipld.Node.
+func (b *Builder) BuildIPLD() (ipld.Node, error) {
+	args, err := b.Build()
+	if err != nil {
+		return nil, err
+	}
+
+	return args.ToIPLD()
+}
+
+// MustBuild is the same as Build except it panics if an error occurs.
+func (b *Builder) MustBuild() *Args {
+	args, err := b.Build()
+
+	if err != nil {
+		panic(b.errs)
+	}
+
+	return args
+}
+
+// MustBuildIPLD is the same as BuildIPLD except it panics if an error
+// occurs.
+func (b *Builder) MustBuildIPLD() ipld.Node {
+	node, err := b.BuildIPLD()
+	if err != nil {
+		panic(err)
+	}
+
+	return node
+}

pkg/args/builder_test.go

@@ -0,0 +1,81 @@
+package args_test
+
+import (
+	"testing"
+
+	"github.com/ipld/go-ipld-prime"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/ucan-wg/go-ucan/pkg/args"
+)
+
+func TestBuilder_XXX(t *testing.T) {
+	t.Parallel()
+
+	const (
+		keyOne = "key1"
+		valOne = "string"
+		keyTwo = "key2"
+		valTwo = 42
+	)
+
+	exp := args.New()
+	exp.Add(keyOne, valOne)
+	exp.Add(keyTwo, valTwo)
+
+	expNode, err := exp.ToIPLD()
+	require.NoError(t, err)
+
+	disjointKeys := args.NewBuilder().
+		Add(keyOne, valOne).
+		Add(keyTwo, valTwo)
+
+	duplicateKeys := args.NewBuilder().
+		Add(keyOne, valOne).
+		Add(keyTwo, valTwo).
+		Add(keyOne, "oh no!")
+
+	t.Run("MustBuild succeeds with disjoint keys", func(t *testing.T) {
+		t.Parallel()
+
+		var act *args.Args
+
+		require.NotPanics(t, func() {
+			act = disjointKeys.MustBuild()
+		})
+		assert.Equal(t, exp, act)
+	})
+
+	t.Run("MustBuild fails with duplicate keys", func(t *testing.T) {
+		t.Parallel()
+
+		var act *args.Args
+
+		require.Panics(t, func() {
+			act = duplicateKeys.MustBuild()
+		})
+		assert.Nil(t, act)
+	})
+
+	t.Run("MustBuildIPLD succeeds with disjoint keys", func(t *testing.T) {
+		t.Parallel()
+
+		var act ipld.Node
+
+		require.NotPanics(t, func() {
+			act = disjointKeys.MustBuildIPLD()
+		})
+		assert.Equal(t, expNode, act)
+	})
+
+	t.Run("MustBuildIPLD fails with duplicate keys", func(t *testing.T) {
+		t.Parallel()
+
+		var act ipld.Node
+
+		require.Panics(t, func() {
+			act = duplicateKeys.MustBuildIPLD()
+		})
+		assert.Nil(t, act)
+	})
+}