When running apex tests through the VS code command palette, any failing tests will throw a misleading error message.
'Successfully ran with failing tests' (warning symbol?)
'SFDX: Invoke Apex Tests... failed to run'
Output shows 'sfdx force:apex:test:run --resultformat human --loglevel error ended with exit code 100'

VS Code Version:
1.22.2
SF Extensions: 42.12.0
SFDX CLI Version:
v42.0
OS and version:
Windows 10
Internal Work Item: W-5171290
@Sweetman - I believe that you also raised this up. Do we already have the mechanisms in place to fix this? Or does this require a larger effort?
The mechanisms in place can be altered to fix this. Right now we only check for a 0 exit code in the notificationService and the CLI seems to have established 100 for test failures for apex/lightning. We would just be altering the notificationService.reportExecutionStatus to account for the test exit code. Another option is to write a separate reportExecutionStatus method for test commands if we want to separate it out for some reason.
Any update on this? We're also seeing this in our Blueocean (Jenkins) pipelines.
Are there any known workarounds?
This was addressed by PR #683
I am running this command: sfdx force:apex:test:run -l RunLocalTests -d ReleaseTest_Results -u %DEP_USER% --resultformat junit --codecoverage -w 200
sfdx version: 7.23.1-ced0ec4940.
I get an exit code of 100.
Can you please help?
I am getting this issue as well:
sfdx-cli/7.74.1 win32-x64 node-v10.15.3
VS Code 1.49.2
Most helpful comment
I am running this command: sfdx force:apex:test:run -l RunLocalTests -d ReleaseTest_Results -u %DEP_USER% --resultformat junit --codecoverage -w 200
sfdx version: 7.23.1-ced0ec4940.
I get an exit code of 100.
Can you please help?