Add unit tests for android/neverallow.go

Bug: 74506774
Test: lunch aosp_walleye-userdebug && make  # runs unit tests
Change-Id: Ibde685d7213713be219681cb039ad58a43d9c377

android/testing.go

@@ -17,6 +17,7 @@ package android
 import (
 	"fmt"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"testing"
 
@@ -163,3 +164,26 @@ func FailIfErrored(t *testing.T, errs []error) {
 		t.FailNow()
 	}
 }
+
+func FailIfNoMatchingErrors(t *testing.T, pattern string, errs []error) {
+	t.Helper()
+
+	matcher, err := regexp.Compile(pattern)
+	if err != nil {
+		t.Errorf("failed to compile regular expression %q because %s", pattern, err)
+	}
+
+	found := false
+	for _, err := range errs {
+		if matcher.FindStringIndex(err.Error()) != nil {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Errorf("missing the expected error %q (checked %d error(s))", pattern, len(errs))
+		for i, err := range errs {
+			t.Errorf("errs[%d] = %s", i, err)
+		}
+	}
+}