diff --git a/api/internal/target/customconfig_test.go b/api/krusty/customconfig_test.go
similarity index 85%
rename from api/internal/target/customconfig_test.go
rename to api/krusty/customconfig_test.go
index ce2b9efc6..bba81d5ac 100644
--- a/api/internal/target/customconfig_test.go
+++ b/api/krusty/customconfig_test.go
@@ -1,15 +1,13 @@
 // Copyright 2019 The Kubernetes Authors.
 // SPDX-License-Identifier: Apache-2.0
 
-package target_test
+package krusty_test
 
 import (
 	"testing"
-
-	kusttest_test "sigs.k8s.io/kustomize/api/testutils/kusttest"
 )
 
-func makeBaseReferencingCustomConfig(th *kusttest_test.KustTestHarness) {
+func makeBaseReferencingCustomConfig(th testingHarness) {
 	th.WriteK("/app/base", `
 namePrefix: x-
 commonLabels:
@@ -74,9 +72,9 @@ spec:
 }
 
 func TestCustomConfig(t *testing.T) {
-	th := kusttest_test.NewKustTestHarness(t, "/app/base")
+	th := makeTestHarness(t)
 	makeBaseReferencingCustomConfig(th)
-	th.WriteDefaultConfigs("/app/base/config/defaults.yaml")
+	th.WriteLegacyConfigs("/app/base/config/defaults.yaml")
 	th.WriteF("/app/base/config/custom.yaml", `
 nameReference:
 - kind: Gorilla
@@ -91,10 +89,7 @@ varReference:
 - path: spec/food
   kind: AnimalPark
 `)
-	m, err := th.MakeKustTarget().MakeCustomizedResMap()
-	if err != nil {
-		t.Fatalf("Err: %v", err)
-	}
+	m := th.Run("/app/base", th.MakeDefaultOptions())
 	th.AssertActualEqualsExpected(m, `
 kind: AnimalPark
 metadata:
@@ -140,9 +135,9 @@ spec:
 }
 
 func TestCustomConfigWithDefaultOverspecification(t *testing.T) {
-	th := kusttest_test.NewKustTestHarness(t, "/app/base")
+	th := makeTestHarness(t)
 	makeBaseReferencingCustomConfig(th)
-	th.WriteDefaultConfigs("/app/base/config/defaults.yaml")
+	th.WriteLegacyConfigs("/app/base/config/defaults.yaml")
 	// Specifying namePrefix here conflicts with (is the same as)
 	// the defaults written above.  This is intentional in the
 	// test to assure duplicate config doesn't cause problems.
@@ -162,10 +157,7 @@ varReference:
 - path: spec/food
   kind: AnimalPark
 `)
-	m, err := th.MakeKustTarget().MakeCustomizedResMap()
-	if err != nil {
-		t.Fatalf("Err: %v", err)
-	}
+	m := th.Run("/app/base", th.MakeDefaultOptions())
 	th.AssertActualEqualsExpected(m, `
 kind: AnimalPark
 metadata:
@@ -211,9 +203,9 @@ spec:
 }
 
 func TestFixedBug605_BaseCustomizationAvailableInOverlay(t *testing.T) {
-	th := kusttest_test.NewKustTestHarness(t, "/app/overlay")
+	th := makeTestHarness(t)
 	makeBaseReferencingCustomConfig(th)
-	th.WriteDefaultConfigs("/app/base/config/defaults.yaml")
+	th.WriteLegacyConfigs("/app/base/config/defaults.yaml")
 	th.WriteF("/app/base/config/custom.yaml", `
 nameReference:
 - kind: Gorilla
@@ -255,12 +247,7 @@ spec:
   gorillaRef:
     name: ursus
 `)
-
-	m, err := th.MakeKustTarget().MakeCustomizedResMap()
-	if err != nil {
-		t.Fatalf("Err: %v", err)
-	}
-
+	m := th.Run("/app/overlay", th.MakeDefaultOptions())
 	th.AssertActualEqualsExpected(m, `
 kind: AnimalPark
 metadata:
diff --git a/api/krusty/kustomizer_test.go b/api/krusty/kustomizer_test.go
index 8c88732c4..1dc5315d6 100644
--- a/api/krusty/kustomizer_test.go
+++ b/api/krusty/kustomizer_test.go
@@ -1,7 +1,6 @@
 // Copyright 2019 The Kubernetes Authors.
 // SPDX-License-Identifier: Apache-2.0
 
-// TODO: move most of the tests in the api/target package to this package.
 package krusty_test
 
 import (
@@ -11,12 +10,11 @@ import (
 	"sigs.k8s.io/kustomize/api/krusty"
 )
 
-// TODO: move most of the tests in api/internal/target
-// to this package, as they are all high level tests and
-// examples appropriate to this level and package.
-// The following test isn't much more than a usage example;
-// everything is actually tested down in api/internal/target.
-func TestSomething(t *testing.T) {
+// A simple usage example - just shows what happens when
+// there are no files to read.  For more substantial tests
+// and examples, see other tests in this package.
+// TODO: https://github.com/kubernetes-sigs/kustomize/issues/1862
+func TestEmptyFileSystem(t *testing.T) {
 	fSys := filesys.MakeFsInMemory()
 	b := krusty.MakeKustomizer(fSys, krusty.MakeDefaultOptions())
 	_, err := b.Run("noSuchThing")
diff --git a/api/krusty/testingharness_test.go b/api/krusty/testingharness_test.go
index 17d0ac790..b37a1c0f3 100644
--- a/api/krusty/testingharness_test.go
+++ b/api/krusty/testingharness_test.go
@@ -11,6 +11,7 @@ import (
 
 	"sigs.k8s.io/kustomize/api/filesys"
 	"sigs.k8s.io/kustomize/api/konfig"
+	"sigs.k8s.io/kustomize/api/konfig/builtinpluginconsts"
 	. "sigs.k8s.io/kustomize/api/krusty"
 	"sigs.k8s.io/kustomize/api/resmap"
 	"sigs.k8s.io/kustomize/api/types"
@@ -176,3 +177,15 @@ func tabToSpace(input string) string {
 	}
 	return strings.Join(result, "")
 }
+
+func (th testingHarness) WriteLegacyConfigs(fName string) {
+	m := builtinpluginconsts.GetDefaultFieldSpecsAsMap()
+	var content []byte
+	for _, tCfg := range m {
+		content = append(content, []byte(tCfg)...)
+	}
+	err := th.fSys.WriteFile(fName, content)
+	if err != nil {
+		th.t.Fatalf("unable to add file %s", fName)
+	}
+}
diff --git a/api/internal/target/transformersarrays_test.go b/api/krusty/transformersarrays_test.go
similarity index 91%
rename from api/internal/target/transformersarrays_test.go
rename to api/krusty/transformersarrays_test.go
index 6e043d31b..90f13874d 100644
--- a/api/internal/target/transformersarrays_test.go
+++ b/api/krusty/transformersarrays_test.go
@@ -1,15 +1,13 @@
 // Copyright 2019 The Kubernetes Authors.
 // SPDX-License-Identifier: Apache-2.0
 
-package target_test
+package krusty_test
 
 import (
 	"testing"
-
-	kusttest_test "sigs.k8s.io/kustomize/api/testutils/kusttest"
 )
 
-func makeStatefulSetKustomization(th *kusttest_test.KustTestHarness) {
+func makeStatefulSetKustomization(th testingHarness) {
 	th.WriteK("/app", `
 commonLabels:
   notIn: arrays
@@ -92,12 +90,9 @@ spec:
 }
 
 func TestTransformersNoCreateArrays(t *testing.T) {
-	th := kusttest_test.NewKustTestHarness(t, "/app")
+	th := makeTestHarness(t)
 	makeStatefulSetKustomization(th)
-	m, err := th.MakeKustTarget().MakeCustomizedResMap()
-	if err != nil {
-		t.Fatalf("Err: %v", err)
-	}
+	m := th.Run("/app", th.MakeDefaultOptions())
 	th.AssertActualEqualsExpected(m, `
 apiVersion: apps/v1
 kind: StatefulSet
diff --git a/api/internal/target/transformersimage_test.go b/api/krusty/transformersimage_test.go
similarity index 89%
rename from api/internal/target/transformersimage_test.go
rename to api/krusty/transformersimage_test.go
index 6d56c3ee7..1b6d4da77 100644
--- a/api/internal/target/transformersimage_test.go
+++ b/api/krusty/transformersimage_test.go
@@ -1,15 +1,13 @@
 // Copyright 2019 The Kubernetes Authors.
 // SPDX-License-Identifier: Apache-2.0
 
-package target_test
+package krusty_test
 
 import (
 	"testing"
-
-	kusttest_test "sigs.k8s.io/kustomize/api/testutils/kusttest"
 )
 
-func makeTransfomersImageBase(th *kusttest_test.KustTestHarness) {
+func makeTransfomersImageBase(th testingHarness) {
 	th.WriteK("/app/base", `
 resources:
 - deploy1.yaml
@@ -94,8 +92,7 @@ spec3:
 }
 
 func TestIssue1281_JsonPatchAndImageTag(t *testing.T) {
-	th := kusttest_test.NewKustTestHarness(t, "/app")
-
+	th := makeTestHarness(t)
 	th.WriteK("/app", `
 resources:
 - deployment.yaml
@@ -147,10 +144,7 @@ spec:
    "value": { "image": "costello" } } ]
 `)
 
-	m, err := th.MakeKustTarget().MakeCustomizedResMap()
-	if err != nil {
-		t.Fatalf("Err: %v", err)
-	}
+	m := th.Run("/app", th.MakeDefaultOptions())
 	th.AssertActualEqualsExpected(m, `
 apiVersion: apps/v1
 kind: Deployment
@@ -178,12 +172,9 @@ spec:
 }
 
 func TestTransfomersImageDefaultConfig(t *testing.T) {
-	th := kusttest_test.NewKustTestHarness(t, "/app/base")
+	th := makeTestHarness(t)
 	makeTransfomersImageBase(th)
-	m, err := th.MakeKustTarget().MakeCustomizedResMap()
-	if err != nil {
-		t.Fatalf("Err: %v", err)
-	}
+	m := th.Run("/app/base", th.MakeDefaultOptions())
 	th.AssertActualEqualsExpected(m, `
 apiVersion: v1
 group: apps
@@ -242,7 +233,7 @@ spec3:
 `)
 }
 
-func makeTransfomersImageCustomBase(th *kusttest_test.KustTestHarness) {
+func makeTransfomersImageCustomBase(th testingHarness) {
 	th.WriteK("/app/base", `
 resources:
 - custom.yaml
@@ -313,13 +304,11 @@ images:
   path: spec3/template/spec/myInitContainers/image
 `)
 }
+
 func TestTransfomersImageCustomConfig(t *testing.T) {
-	th := kusttest_test.NewKustTestHarness(t, "/app/base")
+	th := makeTestHarness(t)
 	makeTransfomersImageCustomBase(th)
-	m, err := th.MakeKustTarget().MakeCustomizedResMap()
-	if err != nil {
-		t.Fatalf("Err: %v", err)
-	}
+	m := th.Run("/app/base", th.MakeDefaultOptions())
 	th.AssertActualEqualsExpected(m, `
 kind: customKind
 metadata:
@@ -357,7 +346,7 @@ spec3:
 `)
 }
 
-func makeTransfomersImageKnativeBase(th *kusttest_test.KustTestHarness) {
+func makeTransfomersImageKnativeBase(th testingHarness) {
 	th.WriteK("/app/base", `
 resources:
 - knative.yaml
@@ -389,12 +378,9 @@ images:
 }
 
 func TestTransfomersImageKnativeConfig(t *testing.T) {
-	th := kusttest_test.NewKustTestHarness(t, "/app/base")
+	th := makeTestHarness(t)
 	makeTransfomersImageKnativeBase(th)
-	m, err := th.MakeKustTarget().MakeCustomizedResMap()
-	if err != nil {
-		t.Fatalf("Err: %v", err)
-	}
+	m := th.Run("/app/base", th.MakeDefaultOptions())
 	th.AssertActualEqualsExpected(m, `
 apiVersion: serving.knative.dev/v1alpha1
 kind: Service