Flaky EtcdMetadataReportTest.testStoreConsumer:NoClassDefFoundError

[sonymoon]

• I have searched the issues of this repository and believe that this is not a duplicate.
• I have checked the FAQ of this repository and believe that this is not a duplicate.

Environment

• Dubbo version: 2.7.4-SNAPSHOT
• Operating System version: "mac os x", version: "10.12.6", arch: "x86_64", family: "mac"
• Java version: 1.8.0_131

Steps to reproduce this issue

1. just run UT EtcdMetadataReportTest.testStoreConsumer in IDEA
   or mvn clean install -DskipTests=false from cmd.

Expected Result

UT succeeds

Actual Result

Ex:

IDEA

java.lang.NoClassDefFoundError: com/google/common/base/Preconditions

	at io.etcd.jetcd.ClientBuilder.endpoints(ClientBuilder.java:82)
	at org.apache.dubbo.metadata.store.etcd.EtcdMetadataReportTest.setUp(EtcdMetadataReportTest.java:64

mvn build with clean install

[ERROR] Tests run: 2, Failures: 0, Errors: 1, Skipped: 1, Time elapsed: 4.798 s <<< FAILURE! - in org.apache.dubbo.metadata.store.etcd.EtcdMetadataReportTest
[ERROR] testStoreConsumer  Time elapsed: 2.127 s  <<< ERROR!
java.lang.NoClassDefFoundError: com/google/common/base/Preconditions
        at org.apache.dubbo.metadata.store.etcd.EtcdMetadataReportTest.setUp(EtcdMetadataReportTest.java:64)
Caused by: java.lang.ClassNotFoundException: com.google.common.base.Preconditions
        at org.apache.dubbo.metadata.store.etcd.EtcdMetadataReportTest.setUp(EtcdMetadataReportTest.java:64)

[sonymoon]

jetcd-core needs guava dependency which is absent in test classpath

[CrazyHZM]

Try it with the latest version, if you still have problems, you can reopen the issues