Additional basic tests around strings.

_rsrch/nodesolution/impls/string_test.go

+package impls
+
+import (
+	"testing"
+
+	"github.com/ipld/go-ipld-prime/_rsrch/nodesolution/impls/tests"
+)
+
+func TestString(t *testing.T) {
+	tests.SpecTestString(t, Style__String{})
+}

_rsrch/nodesolution/impls/tests/stringSpecs.go

+package tests
+
+import (
+	"testing"
+
+	. "github.com/warpfork/go-wish"
+
+	ipld "github.com/ipld/go-ipld-prime/_rsrch/nodesolution"
+)
+
+func SpecTestString(t *testing.T, ns ipld.NodeStyle) {
+	t.Run("string node", func(t *testing.T) {
+		nb := ns.NewBuilder()
+		err := nb.AssignString("asdf")
+		Wish(t, err, ShouldEqual, nil)
+		n := nb.Build()
+
+		Wish(t, n.ReprKind(), ShouldEqual, ipld.ReprKind_String)
+		Wish(t, n.IsNull(), ShouldEqual, false)
+		x, err := n.AsString()
+		Wish(t, err, ShouldEqual, nil)
+		Wish(t, x, ShouldEqual, "asdf")
+	})
+}