java.lang.IllegalArgumentException: Log tag "okhttp3.mockwebserver.MockWebServer" exceeds limit of 23 characters

Some points to clarify that this is not a duplicate question as someone suggested:

• This is a "runtime crash" caused by long log tag name. i.e. okhttp3.mockwebserver.MockWebServer, this is not an IDE lint error.
• This crash is caused by a third party dependency, i.e. MockWebServer. And thanks to Yuri Schimke for raising a bug
  Fix android logging with MockWebServer.
• I have provided my fix in my answer https://stackoverflow.com/a/63388805/8034839.

Original question:

I am working on Android web service tests using Expresso and MockWebServer, however I encounter below exception that tells me the log tag issue:

>"okhttp3.mockwebserver.MockWebServer" exceeds limit of 23 characters.

Detailed stack trace is as following:

2020-08-13 11:31:13.277 16901-17085/com.xxx.app I/okhttp.OkHttpClient: <-- HTTP FAILED: java.net.SocketTimeoutException: timeout
2020-08-13 11:31:13.280 16901-17346/com.xxx.app E/AndroidRuntime: FATAL EXCEPTION: MockWebServer TaskRunner
    Process: com.xxx.app, PID: 16901
    java.lang.IllegalArgumentException: Log tag "okhttp3.mockwebserver.MockWebServer" exceeds limit of 23 characters
    
        at android.util.Log.isLoggable(Native Method)
        at okhttp3.internal.platform.android.AndroidLog.androidLog$okhttp(AndroidLog.kt:66)
        at okhttp3.internal.platform.android.AndroidLogHandler.publish(AndroidLog.kt:39)
        at java.util.logging.Logger.log(Logger.java:615)
        at java.util.logging.Logger.doLog(Logger.java:636)
        at java.util.logging.Logger.log(Logger.java:725)
        at okhttp3.mockwebserver.MockWebServer$serveConnection$$inlined$execute$1.runOnce(TaskQueue.kt:224)
        at okhttp3.internal.concurrent.TaskRunner.runTask(TaskRunner.kt:116)
        at okhttp3.internal.concurrent.TaskRunner.access$runTask(TaskRunner.kt:42)
        at okhttp3.internal.concurrent.TaskRunner$runnable$1.run(TaskRunner.kt:65)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
        at java.lang.Thread.run(Thread.java:762)
2020-08-13 11:31:13.293 16901-17346/com.xxx.app I/Process: Sending signal. PID: 16901 SIG: 9

I have figured out the workaround for this issue after digging into the source code of MockWebServer.kt. Inside this file, there is a property like below:

private val logger = Logger.getLogger(MockWebServer::class.java.name)

The MockWebServer::class.java.name will return a full class name okhttp3.mockwebserver.MockWebServer, obviously, this name as an Android log tag is already longer than 23 chars. The fix is using Kotlin reflection to replace the logger property. Reflection code is as below:

fun <T : Any> T.setPrivateProperty(variableName: String, data: Any): Any? {
    return javaClass.getDeclaredField(variableName).let { field ->
        field.isAccessible = true
        field.set(this, data)
        return@let field.get(this)
    }
}

Inside the @before method, set the logger tag with simpleName

val mockWebServer = MockWebServer() // this is declared inside test class.

@Before
fun setup() {

    mockWebServer.setAndReturnPrivateProperty("logger", 
        Logger.getLogger(MockWebServer::class.java.simpleName))

    mockWebServer.start(8080)
}    

MockWebServer::class.java.simpleName will return a shorter class name and fix the issue.

it's due to Log API doesn't allow tag that exceeds 23 characters.

You can disable the lint checking by following [Terence's answer](https://stackoverflow.com/a/28738249/12676247 "You can disable it if you so choose"), but you've been warned.

for better understanding visit :
[The logging tag can be at most 23 characters](https://stackoverflow.com/questions/28168622/the-logging-tag-can-be-at-most-23-characters#:~:text=From%20Android%20Studio's%20Recent%20Changes,tag%20that%20exceeds%2023%20characters. "The logging tag can be at most 23 characters")