Capture last TEST Run results AZURE DevOps

You could retrieve the list of test runs, the sort descending the result on ID, since the most recent test run has the greatest ID. Then get the first item of the result. All of this shown below in powershell:

$testingBaseUrl = "https://dev.azure.com/cbre/Research%20Engine/_apis/test/runs"
$testingUrl = $testingBaseUrl + "?api-version=5.0"
$testingUrl = $testingUrl + "-preview.2"

write-host $testingUrl


#create auth header to use for REST calls
$username = "RKesavana"
$token = "your token"  Refer to my blog of how to create Personal access tokens  

#create auth header to use for REST calls 
$accessToken = ("{0}:{1}" -f $username,$token) 
$accessToken = [System.Text.Encoding]::UTF8.GetBytes($accessToken) 
$accessToken = [System.Convert]::ToBase64String($accessToken) 
$headers = @{Authorization=("Basic {0}" -f $accessToken)} 


try{
# write-host "To fetch LIST all the Test ID's information"
$testRuns=Invoke-RestMethod -Uri $testingUrl -Method Get -Headers $headers
$testRunsIdSorted = $testRuns.value | sort-object id -Descending
# write-host $testRunsIdSorted

$testURLByRunID= $testingBaseUrl+"/"+$($testRunsIdSorted[0].id)
$testURLByRunID= $testURLByRunID+ "?api-version=5.0"
$testURLByRunID = $testURLByRunID + "-preview.2"

write-host "To fetch the MOST RECENT run Test RUN ID"
write-host $testURLByRunID
$mostRecentTestRun = Invoke-RestMethod -Uri  $testURLByRunID -Headers $headers -Method Get | Select-Object id,name,url,build,isAutomated,iteration,owner,project,startedDate,completedDate,state,totalTests,incompleteTests,notApplicableTests,passedTests,unanalyzedTests,revision,webAccessUrl

#PRINT the values from the  REST calls 

write-host  "owner" $mostRecentTestRun.owner
write-host "startedDate" $mostRecentTestRun.startedDate
write-host "completedDate" $mostRecentTestRun.completedDate
write-host "totalTests" $mostRecentTestRun.totalTests
write-host "incompleteTests" $mostRecentTestRun.incompleteTests
write-host "notApplicableTests" $mostRecentTestRun.notApplicableTests
write-host "passedTests" $mostRecentTestRun.passedTests
write-host "unanalyzedTests" $mostRecentTestRun.unanalyzedTests
write-host "revision" $mostRecentTestRun.revision
write-host "webAccessUrl" $mostRecentTestRun.webAccessUrl


write-Host "##vso[task.setvariable variable=mostRecentRun;]$mostRecentTestRun


}  Catch  { $exception = $_.Exception
  $respstream = $exception.Response.GetResponseStream()
  $sr = new-object System.IO.StreamReader $respstream
  $ErrorResult = $sr.ReadToEnd()
  write-host $ErrorResult 
}