diff --git a/node/basicnode/int_test.go b/node/basicnode/int_test.go
new file mode 100644
index 00000000..65056b6b
--- /dev/null
+++ b/node/basicnode/int_test.go
@@ -0,0 +1,35 @@
+package basicnode_test
+
+import (
+	qt "github.com/frankban/quicktest"
+	"github.com/ipld/go-ipld-prime/must"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
+	"testing"
+)
+
+func TestBasicInt(t *testing.T) {
+	m := basicnode.NewInt(3)
+	b := m.Prototype().NewBuilder()
+	b.AssignInt(4)
+	n := b.Build()
+	u := basicnode.NewUint(5)
+	qt.Check(t, must.Int(m), qt.Equals, int64(3))
+	qt.Check(t, must.Int(n), qt.Equals, int64(4))
+	qt.Check(t, must.Int(u), qt.Equals, int64(5))
+}
+
+func TestIntErrors(t *testing.T) {
+	x := basicnode.NewInt(3)
+
+	_, err := x.LookupByIndex(0)
+	errExpect := `func called on wrong kind: "LookupByIndex" called on a int node \(kind: int\), but only makes sense on list`
+	qt.Check(t, err, qt.ErrorMatches, errExpect)
+
+	_, err = x.LookupByString("n")
+	errExpect = `func called on wrong kind: "LookupByString" called on a int node \(kind: int\), but only makes sense on map`
+	qt.Check(t, err, qt.ErrorMatches, errExpect)
+
+	_, err = x.LookupByNode(x)
+	errExpect = `func called on wrong kind: "LookupByNode" called on a int node \(kind: int\), but only makes sense on map`
+	qt.Check(t, err, qt.ErrorMatches, errExpect)
+}
diff --git a/node/basicnode/map_test.go b/node/basicnode/map_test.go
index 2417fc62..03e17d9d 100644
--- a/node/basicnode/map_test.go
+++ b/node/basicnode/map_test.go
@@ -1,10 +1,15 @@
 package basicnode_test
 
 import (
+	"fmt"
 	"testing"
 
+	qt "github.com/frankban/quicktest"
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/must"
 	"github.com/ipld/go-ipld-prime/node/basicnode"
 	"github.com/ipld/go-ipld-prime/node/tests"
+	"github.com/ipld/go-ipld-prime/printer"
 )
 
 func TestMap(t *testing.T) {
@@ -46,3 +51,277 @@ func BenchmarkSpec_Unmarshal_Map3StrInt(b *testing.B) {
 func BenchmarkSpec_Unmarshal_MapNStrMap3StrInt(b *testing.B) {
 	tests.BenchmarkSpec_Unmarshal_MapNStrMap3StrInt(b, basicnode.Prototype.Map)
 }
+
+// Test that the map builder cannot be assigned arbitrary values, and trying to
+// will result in a sensible error
+func TestMapAssignError(t *testing.T) {
+	b := basicnode.Prototype.Map.NewBuilder()
+	err := b.AssignBool(true)
+	errExpect := `func called on wrong kind: "AssignBool" called on a map node \(kind: map\), but only makes sense on bool`
+	qt.Check(t, err, qt.ErrorMatches, errExpect)
+
+	err = b.AssignInt(3)
+	errExpect = `func called on wrong kind: "AssignInt" called on a map node \(kind: map\), but only makes sense on int`
+	qt.Check(t, err, qt.ErrorMatches, errExpect)
+
+	err = b.AssignFloat(5.7)
+	errExpect = `func called on wrong kind: "AssignFloat" called on a map node \(kind: map\), but only makes sense on float`
+	qt.Check(t, err, qt.ErrorMatches, errExpect)
+
+	err = b.AssignString("hi")
+	errExpect = `func called on wrong kind: "AssignString" called on a map node \(kind: map\), but only makes sense on string`
+	qt.Check(t, err, qt.ErrorMatches, errExpect)
+
+	err = b.AssignNode(basicnode.NewInt(3))
+	errExpect = `func called on wrong kind: "AssignNode" called on a map node \(kind: int\), but only makes sense on map`
+	qt.Check(t, err, qt.ErrorMatches, errExpect)
+
+	// TODO(dustmop): BeginList, AssignNull, AssignBytes, AssignLink
+}
+
+// Test that the map builder can create map nodes, and AssignNode will copy
+// such a node, and lookup methods on that node will work correctly
+func TestMapBuilder(t *testing.T) {
+	b := basicnode.Prototype.Map.NewBuilder()
+
+	// construct a map of three keys, using the MapBuilder
+	ma, err := b.BeginMap(3)
+	if err != nil {
+		t.Fatal(err)
+	}
+	a := ma.AssembleKey()
+	a.AssignString("cat")
+	a = ma.AssembleValue()
+	a.AssignString("meow")
+
+	a, err = ma.AssembleEntry("dog")
+	if err != nil {
+		t.Fatal(err)
+	}
+	a.AssignString("bark")
+
+	a = ma.AssembleKey()
+	a.AssignString("eel")
+	a = ma.AssembleValue()
+	a.AssignString("zap")
+
+	err = ma.Finish()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// test the builder's prototypes and its key and value prototypes, while we're here
+	np := b.Prototype()
+	qt.Check(t, fmt.Sprintf("%T", np), qt.Equals, "basicnode.Prototype__Map")
+	np = ma.KeyPrototype()
+	qt.Check(t, fmt.Sprintf("%T", np), qt.Equals, "basicnode.Prototype__String")
+	np = ma.ValuePrototype("")
+	qt.Check(t, fmt.Sprintf("%T", np), qt.Equals, "basicnode.Prototype__Any")
+
+	// compare the printed map
+	mapNode := b.Build()
+	actual := printer.Sprint(mapNode)
+
+	expect := `map{
+	string{"cat"}: string{"meow"}
+	string{"dog"}: string{"bark"}
+	string{"eel"}: string{"zap"}
+}`
+	qt.Check(t, expect, qt.Equals, actual)
+
+	// copy the map using AssignNode
+	c := basicnode.Prototype.Map.NewBuilder()
+	err = c.AssignNode(mapNode)
+	if err != nil {
+		t.Fatal(err)
+	}
+	anotherNode := c.Build()
+
+	actual = printer.Sprint(anotherNode)
+	qt.Assert(t, expect, qt.Equals, actual)
+
+	// access values of map, using string
+	r, err := anotherNode.LookupByString("cat")
+	if err != nil {
+		t.Fatal(err)
+	}
+	qt.Check(t, "meow", qt.Equals, must.String(r))
+
+	// access values of map, using node
+	r, err = anotherNode.LookupByNode(basicnode.NewString("dog"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	qt.Check(t, "bark", qt.Equals, must.String(r))
+
+	// access values of map, using PathSegment
+	r, err = anotherNode.LookupBySegment(datamodel.ParsePathSegment("eel"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	qt.Check(t, "zap", qt.Equals, must.String(r))
+
+	// validate the node's prototype
+	np = anotherNode.Prototype()
+	qt.Check(t, fmt.Sprintf("%T", np), qt.Equals, "basicnode.Prototype__Map")
+}
+
+// test that AssignNode will fail if called twice, it expects an empty
+// node to assign to
+func TestMapCantAssignNodeTwice(t *testing.T) {
+	b := basicnode.Prototype.Map.NewBuilder()
+
+	// construct a map of three keys, using the MapBuilder
+	ma, err := b.BeginMap(3)
+	if err != nil {
+		t.Fatal(err)
+	}
+	a := ma.AssembleKey()
+	a.AssignString("cat")
+	a = ma.AssembleValue()
+	a.AssignString("meow")
+
+	a, err = ma.AssembleEntry("dog")
+	if err != nil {
+		t.Fatal(err)
+	}
+	a.AssignString("bark")
+
+	a = ma.AssembleKey()
+	a.AssignString("eel")
+	a = ma.AssembleValue()
+	a.AssignString("zap")
+
+	err = ma.Finish()
+	if err != nil {
+		t.Fatal(err)
+	}
+	mapNode := b.Build()
+
+	// copy the map using AssignNode, works the first time
+	c := basicnode.Prototype.Map.NewBuilder()
+	err = c.AssignNode(mapNode)
+	if err != nil {
+		t.Fatal(err)
+	}
+	qt.Assert(t,
+		func() {
+			_ = c.AssignNode(mapNode)
+		},
+		qt.PanicMatches,
+		// TODO(dustmop): Error message here should be better
+		`misuse`)
+}
+
+func TestMapLookupError(t *testing.T) {
+	b := basicnode.Prototype.Map.NewBuilder()
+
+	// construct a map of three keys, using the MapBuilder
+	ma, err := b.BeginMap(3)
+	if err != nil {
+		t.Fatal(err)
+	}
+	a := ma.AssembleKey()
+	a.AssignString("cat")
+	a = ma.AssembleValue()
+	a.AssignString("meow")
+
+	a, err = ma.AssembleEntry("dog")
+	if err != nil {
+		t.Fatal(err)
+	}
+	a.AssignString("bark")
+
+	a = ma.AssembleKey()
+	a.AssignString("eel")
+	a = ma.AssembleValue()
+	a.AssignString("zap")
+
+	err = ma.Finish()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	mapNode := b.Build()
+
+	_, err = mapNode.LookupByString("frog")
+	qt.Check(t, err, qt.ErrorMatches, `key not found: "frog"`)
+
+	_, err = mapNode.LookupByNode(basicnode.NewInt(3))
+	// TODO(dustmop): This error message is not great. It's about how the
+	// int node could not be converted when the real problem is that this
+	// method should not accept ints as parameters
+	qt.Check(t, err, qt.ErrorMatches, `func called on wrong kind: "AsString" called on a int node \(kind: int\), but only makes sense on string`)
+
+	_, err = mapNode.LookupByIndex(0)
+	qt.Check(t, err, qt.ErrorMatches, `func called on wrong kind: "LookupByIndex" called on a map node \(kind: map\), but only makes sense on list`)
+}
+
+func TestMapNewBuilderUsageError(t *testing.T) {
+	qt.Assert(t,
+		func() {
+			b := basicnode.Prototype.Map.NewBuilder()
+			_ = b.Build()
+		},
+		qt.PanicMatches,
+		`invalid state: assembler must be 'finished' before Build can be called!`)
+
+	// construct an empty map
+	b := basicnode.Prototype.Map.NewBuilder()
+	ma, err := b.BeginMap(0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = ma.Finish()
+	if err != nil {
+		t.Fatal(err)
+	}
+	mapNode := b.Build()
+	actual := printer.Sprint(mapNode)
+
+	expect := `map{}`
+	qt.Check(t, expect, qt.Equals, actual)
+
+	// reset will return the state to 'initial', so Build will panic once again
+	b.Reset()
+	qt.Assert(t,
+		func() {
+			_ = b.Build()
+		},
+		qt.PanicMatches,
+		`invalid state: assembler must be 'finished' before Build can be called!`)
+
+	// assembling a key without a value will cause Finish to panic
+	b.Reset()
+	ma, err = b.BeginMap(0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	a := ma.AssembleKey()
+	a.AssignString("cat")
+	qt.Assert(t,
+		func() {
+			_ = ma.Finish()
+		},
+		qt.PanicMatches,
+		// TODO(dustmop): Error message here should be better
+		`misuse`)
+}
+
+func TestMapDupKeyError(t *testing.T) {
+	b := basicnode.Prototype.Map.NewBuilder()
+
+	// construct a map with duplicate keys
+	ma, err := b.BeginMap(3)
+	if err != nil {
+		t.Fatal(err)
+	}
+	a := ma.AssembleKey()
+	a.AssignString("cat")
+	a = ma.AssembleValue()
+	a.AssignString("meow")
+	a = ma.AssembleKey()
+	err = a.AssignString("cat")
+
+	qt.Check(t, err, qt.ErrorMatches, `cannot repeat map key "cat"`)
+}