From ec604cffc33c1c35ee5e0b6950d56c8145a819a3 Mon Sep 17 00:00:00 2001
From: Dan Ryan <dan@danryan.co>
Date: Thu, 15 Nov 2018 00:49:15 -0500
Subject: [PATCH] Add distributed testing for azure

Signed-off-by: Dan Ryan <dan@danryan.co>
---
 .azure-pipelines/steps/DistributeTests.ps1 | 43 ++++++++++++++++++++++
 .azure-pipelines/steps/run-tests.yml       |  7 +++-
 2 files changed, 48 insertions(+), 2 deletions(-)
 create mode 100644 .azure-pipelines/steps/DistributeTests.ps1

diff --git a/.azure-pipelines/steps/DistributeTests.ps1 b/.azure-pipelines/steps/DistributeTests.ps1
new file mode 100644
index 00000000..d9fce4a3
--- /dev/null
+++ b/.azure-pipelines/steps/DistributeTests.ps1
@@ -0,0 +1,43 @@
+<#
+.SYNOPSIS
+    Distribute the tests in VSTS pipeline across multiple agents
+.DESCRIPTION
+    This script slices tests files across multiple agents for faster execution.
+    We search for specific type of file structure (in this example test*), and slice them according to agent number
+    If we encounter multiple files [file1..file10] and if we have 2 agents, agent1 executes tests odd number of files while agent2 executes even number of files
+    For detalied slicing info: https://docs.microsoft.com/en-us/vsts/pipelines/test/parallel-testing-any-test-runner
+    We use JUnit style test results to publish the test reports.
+#>
+
+$tests = Get-ChildItem ..\..\tests\unit,..\..\tests\integration -Filter "test*" # search for test files with specific pattern.
+$totalAgents = [int]$Env:SYSTEM_TOTALJOBSINPHASE # standard VSTS variables available using parallel execution; total number of parallel jobs running
+$agentNumber = [int]$Env:SYSTEM_JOBPOSITIONINPHASE  # current job position
+$testCount = $tests.Count
+
+# below conditions are used if parallel pipeline is not used. i.e. pipeline is running with single agent (no parallel configuration)
+if ($totalAgents -eq 0) {
+    $totalAgents = 1
+}
+if (!$agentNumber -or $agentNumber -eq 0) {
+    $agentNumber = 1
+}
+
+Write-Host "Total agents: $totalAgents"
+Write-Host "Agent number: $agentNumber"
+Write-Host "Total tests: $testCount"
+
+$testsToRun= @()
+
+# slice test files to make sure each agent gets unique test file to execute
+For ($i=$agentNumber; $i -le $testCount;) {
+    $file = $tests[$i-1]
+    $testsToRun = $testsToRun + $file
+    Write-Host "Added $file"
+    $i = $i + $totalAgents
+ }
+
+# join all test files seperated by space. pytest runs multiple test files in following format pytest test1.py test2.py test3.py
+$testFiles = $testsToRun -Join " "
+Write-Host "Test files $testFiles"
+# write these files into variable so that we can run them using pytest in subsequent task.
+Write-Host "##vso[task.setvariable variable=pytestfiles;]$testFiles"
diff --git a/.azure-pipelines/steps/run-tests.yml b/.azure-pipelines/steps/run-tests.yml
index a7b99a13..6515f604 100644
--- a/.azure-pipelines/steps/run-tests.yml
+++ b/.azure-pipelines/steps/run-tests.yml
@@ -1,4 +1,7 @@
 steps:
+- powershell: ./DistributeTests.ps1
+  displayName: 'PowerShell Script to distribute tests'
+
 - powershell: |
     # Fix Git SSL errors
     pip install certifi
@@ -11,8 +14,8 @@ steps:
     Write-Host "##vso[task.setvariable variable=TEMP]T:\"
     $env:TEMP='T:\'
     Write-Host "##vso[task.setvariable variable=TMP]T:\"
-    $env:TEMP='T:\'
-    D:\.venv\Scripts\pipenv run pytest -ra --ignore=pipenv\patched --ignore=pipenv\vendor --junitxml=test-results.xml tests
+    $env:TMP='T:\'
+    D:\.venv\Scripts\pipenv run pytest -ra --ignore=pipenv\patched --ignore=pipenv\vendor --junitxml=test-results.xml "$env:pytestfiles"
   displayName: Run integration tests
 
 - task: PublishTestResults@2