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[java] Improving exception when server returns 504 (WIP) #9354

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Merged
merged 1 commit into from
Apr 6, 2021
Merged

[java] Improving exception when server returns 504 (WIP) #9354

merged 1 commit into from
Apr 6, 2021

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alb-i986
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@alb-i986 alb-i986 commented Apr 3, 2021

Description

Here I'm adding one extra condition to W3CHttpResponseCodec#decode in order to specifically handle 504 Gateway Time-out server errors.

This fix is very similar to the fix that was applied in 6a9c546 (see #7792).

Motivation and Context

While running a test on a Selenium Grid (v3.141.59), I got the following pretty unfriendly exception upon a WebElement#click call:

org.openqa.selenium.json.JsonException: Unable to determine type from: <. Last 1 characters read: <
Build info: version: '3.141.59', revision: 'e82be7d358', time: '2018-11-14T08:17:03'
System info: host: 'Albertos-iMac.local', ip: '192.168.1.130', os.name: 'Mac OS X', os.arch: 'x86_64', os.version: '10.15.7', java.version: '1.8.0_281'
Driver info: driver.version: RemoteWebDriver
    at org.openqa.selenium.json.JsonInput.peek(JsonInput.java:122)
    at org.openqa.selenium.json.JsonTypeCoercer.lambda$null$6(JsonTypeCoercer.java:140)
    at org.openqa.selenium.json.JsonTypeCoercer.coerce(JsonTypeCoercer.java:126)
    at org.openqa.selenium.json.Json.toType(Json.java:69)
    at org.openqa.selenium.json.Json.toType(Json.java:55)
    at org.openqa.selenium.json.Json.toType(Json.java:50)
    at org.openqa.selenium.remote.http.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:87)
    at org.openqa.selenium.remote.http.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:49)
    at org.openqa.selenium.remote.HttpCommandExecutor.execute(HttpCommandExecutor.java:158)
    at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:552)
    at org.openqa.selenium.remote.RemoteWebElement.execute(RemoteWebElement.java:285)
    at org.openqa.selenium.remote.RemoteWebElement.click(RemoteWebElement.java:84)
[..]

Only by debugging the test and stepping through the calls, I was able to find that the server was actually returning a plain text response:

<html><body><h1>504 Gateway Time-out</h1>
The server didn't respond in time.
</body></html>

Screenshot 2021-03-25 at 19 39 07

It shouldn't be required from the end user to do this.

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to change)

Checklist

  • I have read the contributing document.
  • My change requires a change to the documentation.
  • I have updated the documentation accordingly.
  • I have added tests to cover my changes.
  • All new and existing tests passed. (note: I only ran small tests)

PS: I was wondering if it makes sense to extend this special handling logic to any 4XX/5XX errors, instead of only to 405 and 504.
I mean, I would expect the server to return a Json only when the HTTP status is 200.

I did some research and I found that AbstractHttpResponseCodec (the superclass of W3CHttpResponseCodec) is already doing what I was thinking:

selenium/java/client/src/org/openqa/selenium/remote/codec/AbstractHttpResponseCodec.java

Line 105 in fcfbc6b

if (statusCode < 200 || statusCode > 299) {

On the other hand, I also see that in W3CHttpResponseCodec there's a line which expects to get a JSON together with a 500 error 😕

selenium/java/client/src/org/openqa/selenium/remote/codec/w3c/W3CHttpResponseCodec.java

Line 117 in fcfbc6b

HTTP_INTERNAL_ERROR == encodedResponse.getStatus()) {

@shs96c can you maybe spread some light? Tagging you as the author of W3CHttpResponseCodec

Thanks!

@alb-i986
[java] Improving exception when server returns 504
c2fbc63 
Add a special case in W3CHttpResponseCodec handling 504 Gateway Time-out errors.

Before, the end user used to see a pretty unfriendly error:

> JsonException: Unable to determine type from: <. Last 1 characters read: <
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sonarqubecloud bot commented Apr 3, 2021

Kudos, SonarCloud Quality Gate passed!

Bug A 0 Bugs
Vulnerability A 0 Vulnerabilities
Security Hotspot A 0 Security Hotspots
Code Smell A 0 Code Smells

0.0% 0.0% Coverage
0.0% 0.0% Duplication

diemol
diemol approved these changes Apr 6, 2021
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Thank you, @alb-i986!

Perhaps you can join Slack/IRC to continue the conversation about the question asked in this PR.

@diemol diemol merged commit 430c7a4 into SeleniumHQ:trunk Apr 6, 2021
@alb-i986 alb-i986 deleted the fix-W3CHttpResponseCodec-handle-500 branch May 25, 2021 16:32
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