diff --git a/tools/compliance/test_util.go b/tools/compliance/test_util.go
new file mode 100644
index 0000000..46df45e
--- /dev/null
+++ b/tools/compliance/test_util.go
@@ -0,0 +1,215 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package compliance
+
+import (
+	"fmt"
+	"io"
+	"io/fs"
+	"sort"
+	"strings"
+	"testing"
+)
+
+const (
+	// AOSP starts a test metadata file for Android Apache-2.0 licensing.
+	AOSP = `` +
+		`package_name: "Android"
+license_kinds: "SPDX-license-identifier-Apache-2.0"
+license_conditions: "notice"
+`
+)
+
+// toConditionList converts a test data map of condition name to origin names into a ConditionList.
+func toConditionList(lg *LicenseGraph, conditions map[string][]string) ConditionList {
+	cl := make(ConditionList, 0)
+	for name, origins := range conditions {
+		for _, origin := range origins {
+			cl = append(cl, LicenseCondition{name, newTestNode(lg, origin)})
+		}
+	}
+	return cl
+}
+
+// newTestNode constructs a test node in the license graph.
+func newTestNode(lg *LicenseGraph, targetName string) *TargetNode {
+	if _, ok := lg.targets[targetName]; !ok {
+		lg.targets[targetName] = &TargetNode{name: targetName}
+	}
+	return lg.targets[targetName]
+}
+
+// testFS implements a test file system (fs.FS) simulated by a map from filename to []byte content.
+type testFS map[string][]byte
+
+// Open implements fs.FS.Open() to open a file based on the filename.
+func (fs *testFS) Open(name string) (fs.File, error) {
+	if _, ok := (*fs)[name]; !ok {
+		return nil, fmt.Errorf("unknown file %q", name)
+	}
+	return &testFile{fs, name, 0}, nil
+}
+
+// testFile implements a test file (fs.File) based on testFS above.
+type testFile struct {
+	fs   *testFS
+	name string
+	posn int
+}
+
+// Stat not implemented to obviate implementing fs.FileInfo.
+func (f *testFile) Stat() (fs.FileInfo, error) {
+	return nil, fmt.Errorf("unimplemented")
+}
+
+// Read copies bytes from the testFS map.
+func (f *testFile) Read(b []byte) (int, error) {
+	if f.posn < 0 {
+		return 0, fmt.Errorf("file not open: %q", f.name)
+	}
+	if f.posn >= len((*f.fs)[f.name]) {
+		return 0, io.EOF
+	}
+	n := copy(b, (*f.fs)[f.name][f.posn:])
+	f.posn += n
+	return n, nil
+}
+
+// Close marks the testFile as no longer in use.
+func (f *testFile) Close() error {
+	if f.posn < 0 {
+		return fmt.Errorf("file already closed: %q", f.name)
+	}
+	f.posn = -1
+	return nil
+}
+
+// edge describes test data edges to define test graphs.
+type edge struct {
+	target, dep string
+}
+
+// String returns a string representation of the edge.
+func (e edge) String() string {
+	return e.target + " -> " + e.dep
+}
+
+// byEdge orders edges by target then dep name then annotations.
+type byEdge []edge
+
+// Len returns the count of elements in the slice.
+func (l byEdge) Len() int      { return len(l) }
+
+// Swap rearranges 2 elements of the slice so that each occupies the other's
+// former position.
+func (l byEdge) Swap(i, j int) { l[i], l[j] = l[j], l[i] }
+
+// Less returns true when the `i`th element is lexicographically less than
+// the `j`th element.
+func (l byEdge) Less(i, j int) bool {
+	if l[i].target == l[j].target {
+		return l[i].dep < l[j].dep
+	}
+	return l[i].target < l[j].target
+}
+
+// res describes test data resolutions to define test resolution sets.
+type res struct {
+	attachesTo, actsOn, origin, condition string
+}
+
+// toResolutionSet converts a list of res test data into a test resolution set.
+func toResolutionSet(lg *LicenseGraph, data []res) *ResolutionSet {
+	rmap := make(map[*TargetNode]actionSet)
+	for _, r := range data {
+		attachesTo := newTestNode(lg, r.attachesTo)
+		actsOn := newTestNode(lg, r.actsOn)
+		origin := newTestNode(lg, r.origin)
+		if _, ok := rmap[attachesTo]; !ok {
+			rmap[attachesTo] = make(actionSet)
+		}
+		if _, ok := rmap[attachesTo][actsOn]; !ok {
+			rmap[attachesTo][actsOn] = newLicenseConditionSet()
+		}
+		rmap[attachesTo][actsOn].add(origin, r.condition)
+	}
+	return &ResolutionSet{rmap}
+}
+
+// checkSameActions compares an actual action set to an expected action set for a test.
+func checkSameActions(lg *LicenseGraph, asActual, asExpected actionSet, t *testing.T) {
+	rsActual := ResolutionSet{make(map[*TargetNode]actionSet)}
+	rsExpected := ResolutionSet{make(map[*TargetNode]actionSet)}
+	testNode := newTestNode(lg, "test")
+	rsActual.resolutions[testNode] = asActual
+	rsExpected.resolutions[testNode] = asExpected
+	checkSame(&rsActual, &rsExpected, t)
+}
+
+// checkSame compares an actual resolution set to an expected resolution set for a test.
+func checkSame(rsActual, rsExpected *ResolutionSet, t *testing.T) {
+	expectedTargets := rsExpected.AttachesTo()
+	sort.Sort(expectedTargets)
+	for _, target := range expectedTargets {
+		if !rsActual.AttachesToTarget(target) {
+			t.Errorf("unexpected missing target: got AttachesToTarget(%q) is false in %s, want true in %s", target.name, rsActual, rsExpected)
+			continue
+		}
+		expectedRl := rsExpected.Resolutions(target)
+		sort.Sort(expectedRl)
+		actualRl := rsActual.Resolutions(target)
+		sort.Sort(actualRl)
+		if len(expectedRl) != len(actualRl) {
+			t.Errorf("unexpected number of resolutions attach to %q: got %s with %d elements, want %s with %d elements",
+				target.name, actualRl, len(actualRl), expectedRl, len(expectedRl))
+			continue
+		}
+		for i := 0; i < len(expectedRl); i++ {
+			if expectedRl[i].attachesTo.name != actualRl[i].attachesTo.name || expectedRl[i].actsOn.name != actualRl[i].actsOn.name {
+				t.Errorf("unexpected resolution attaches to %q at index %d: got %s, want %s",
+					target.name, i, actualRl[i].asString(), expectedRl[i].asString())
+				continue
+			}
+			expectedConditions := expectedRl[i].Resolves().AsList()
+			actualConditions := actualRl[i].Resolves().AsList()
+			sort.Sort(expectedConditions)
+			sort.Sort(actualConditions)
+			if len(expectedConditions) != len(actualConditions) {
+				t.Errorf("unexpected number of conditions apply to %q acting on %q: got %s with %d elements, want %s with %d elements",
+					target.name, expectedRl[i].actsOn.name,
+					actualConditions, len(actualConditions),
+					expectedConditions, len(expectedConditions))
+				continue
+			}
+			for j := 0; j < len(expectedConditions); j++ {
+				if expectedConditions[j] != actualConditions[j] {
+					t.Errorf("unexpected condition attached to %q acting on %q at index %d: got %s at index %d in %s, want %s in %s",
+						target.name, expectedRl[i].actsOn.name, i,
+						actualConditions[j].asString(":"), j, actualConditions,
+						expectedConditions[j].asString(":"), expectedConditions)
+				}
+			}
+		}
+
+	}
+	actualTargets := rsActual.AttachesTo()
+	sort.Sort(actualTargets)
+	for i, target := range actualTargets {
+		if !rsExpected.AttachesToTarget(target) {
+			t.Errorf("unexpected target: got %q element %d in AttachesTo() %s with %d elements in %s, want %s with %d elements in %s",
+				target.name, i, actualTargets, len(actualTargets), rsActual, expectedTargets, len(expectedTargets), rsExpected)
+		}
+	}
+}