Graph graph = new Graph();
        graph.addEdge("a1", "a2");
        assertThrows(Graph.CycleDetectedException.class, () -> graph.addEdge("a2", "a1"));
    }

    @Test
    public void testPerf() throws IOException {
        List<String[]> data = new ArrayList<>();
        String k = null;
        for (String line : Files.readAllLines(Paths.get("src/test/resources/dag.txt"))) {
            if (line.startsWith("\t")) {

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package testcert contains a test-only localhost certificate.
package testcert

import "strings"

// LocalhostCert is a PEM-encoded TLS cert with SAN IPs
// "127.0.0.1" and "[::1]", expiring at Jan 29 16:00:00 2084 GMT.
// generated from src/crypto/tls:

	t.tester = t.tester.ClusterScope()
	return t
}

func (t *Tester) Namer(namer func(int) string) *Tester {
	t.tester = t.tester.Namer(namer)
	return t
}

func (t *Tester) AllowCreateOnUpdate() *Tester {
	t.tester = t.tester.AllowCreateOnUpdate()
	return t
}

func (t *Tester) GeneratesName() *Tester {
	t.tester = t.tester.GeneratesName()
	return t
}

func (t *Tester) ReturnDeletedObject() *Tester {

    return !disjoint(a, b);
  }

  private static Method extractMethod(Test test) {
    if (test instanceof AbstractTester) {
      AbstractTester<?> tester = (AbstractTester<?>) test;
      return Helpers.getMethod(tester.getClass(), tester.getTestMethodName());
    } else if (test instanceof TestCase) {
      TestCase testCase = (TestCase) test;
      return Helpers.getMethod(testCase.getClass(), testCase.getName());

    return !disjoint(a, b);
  }

  private static Method extractMethod(Test test) {
    if (test instanceof AbstractTester) {
      AbstractTester<?> tester = (AbstractTester<?>) test;
      return Helpers.getMethod(tester.getClass(), tester.getTestMethodName());
    } else if (test instanceof TestCase) {
      TestCase testCase = (TestCase) test;
      return Helpers.getMethod(testCase.getClass(), testCase.getName());

package com.google.common.collect.testing.testers;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import com.google.common.collect.testing.Helpers;
import java.util.Collection;
import java.util.List;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.junit.Ignore;

/**
 * Base class for list testers.
 *
 * @author George van den Driessche

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect.testing.testers;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import java.util.Set;
import org.junit.Ignore;

/** @author George van den Driessche */

package com.google.common.collect.testing.testers;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import com.google.common.collect.testing.Helpers;
import java.util.Collection;
import java.util.List;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.junit.Ignore;

/**
 * Base class for list testers.
 *
 * @author George van den Driessche

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect.testing.testers;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import java.util.Set;
import org.junit.Ignore;

/** @author George van den Driessche */

  }

  public void testNullEqualityGroup() {
    EqualsTester tester = new EqualsTester();
    try {
      tester.addEqualityGroup((Object[]) null);
      fail();
    } catch (NullPointerException e) {
    }
  }

  public void testNullObjectInEqualityGroup() {
    EqualsTester tester = new EqualsTester();
    try {
      tester.addEqualityGroup(1, null, 3);
      fail();