diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
new file mode 100644
index 0000000..841d3f5
--- /dev/null
+++ b/.github/workflows/CI.yml
@@ -0,0 +1,45 @@
+name: CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+  schedule:
+    - cron: "0 0 * * *"
+
+jobs:
+  powershell-core:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Restore
+        run: tools/restore.ps1
+        shell: pwsh
+
+      - name: test
+        run: tools/run-tests.ps1
+        shell: pwsh 
+  
+  windows-powershell:
+    runs-on: windows-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Restore
+        run: tools/restore.ps1
+        shell: powershell
+
+      - name: test
+        run: tools/run-tests.ps1
+        shell: powershell 
+
+      - name: Test manifest
+        run: Test-ModuleManifest -Path ./FeatureFlags.psd1
+        shell: powershell
\ No newline at end of file
diff --git a/README.md b/README.md
index 4ddd59a..257f1e1 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,3 @@
-[![Build Status](https://dev.azure.com/PowerShell-FeatureFlags/PowerShell-FeatureFlags/_apis/build/status/microsoft.PowerShell-FeatureFlags?branchName=master)](https://dev.azure.com/PowerShell-FeatureFlags/PowerShell-FeatureFlags/_build/latest?definitionId=1&branchName=master)
 [![Nuget](https://img.shields.io/nuget/v/FeatureFlags.PowerShell)](https://www.nuget.org/packages/FeatureFlags.PowerShell/1.0.0)
 [![Platforms](https://img.shields.io/powershellgallery/p/FeatureFlags.svg)](https://www.powershellgallery.com/packages/FeatureFlags/)
 [![FeatureFlags](https://img.shields.io/powershellgallery/v/FeatureFlags.svg)](https://www.powershellgallery.com/packages/FeatureFlags/)
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
deleted file mode 100644
index af2f3f9..0000000
--- a/azure-pipelines.yml
+++ /dev/null
@@ -1,74 +0,0 @@
-trigger:
-  branches:
-    include:
-      - master
-  paths:
-    exclude:
-      - README.md
-      - examples/*
-      - .gitignore
-
-schedules:
-- cron: "0 0 * * *"
-  displayName: Daily CI build
-  always: true
-  branches:
-    include:
-    - master
-
-jobs:
-- job: PowerShellCore
-  strategy:
-    matrix:
-      linux:
-        imageName: 'ubuntu-18.04'
-      mac:
-        imageName: 'macos-10.15'
-      windows:
-        imageName: 'windows-2019'
-
-  pool:
-    vmImage: $(imageName)
-
-  steps:
-  - task: PowerShell@2
-    displayName: Restore
-    inputs:
-      filePath: 'tools/restore.ps1'
-      pwsh: true
-    
-  - task: PowerShell@2
-    displayName: Test
-    inputs:
-      filePath: 'tools/run-tests.ps1'
-      pwsh: true
-  
-  - task: PublishTestResults@2
-    inputs:
-      testResultsFormat: "NUnit"
-      testResultsFiles: "test/results.xml"
-
-- job: WindowsPowershell
-  pool:
-    vmImage: 'vs2017-win2016'
-  steps:
-  - task: PowerShell@2
-    displayName: Restore
-    inputs:
-      filePath: 'tools/restore.ps1'
-    
-  - task: PowerShell@2
-    displayName: Test
-    inputs:
-      filePath: 'tools/run-tests.ps1'
-
-  - task: PublishTestResults@2
-    inputs:
-      testResultsFormat: "NUnit"
-      testResultsFiles: "test/results.xml"
-
-  - task: PowerShell@2
-    displayName: TestManifest
-    inputs:
-      targetType: inline
-      script: 'Test-ModuleManifest -Path ./FeatureFlags.psd1'
\ No newline at end of file
diff --git a/test/FeatureFlags.Tests.ps1 b/test/FeatureFlags.Tests.ps1
index 3ec8676..3d82a29 100644
--- a/test/FeatureFlags.Tests.ps1
+++ b/test/FeatureFlags.Tests.ps1
@@ -4,18 +4,20 @@
            https://github.com/pester/Pester/wiki/Installation-and-Update.
            After updating, run the Invoke-Pester cmdlet from the project directory.
 #>
-$ModuleName = "FeatureFlags"
-Get-Module $ModuleName | Remove-Module -Force
-Import-Module $PSScriptRoot\test-functions.psm1
+BeforeAll {
+    $ModuleName = "FeatureFlags"
+    Get-Module $ModuleName | Remove-Module -Force
+    Import-Module $PSScriptRoot\test-functions.psm1
 
-$VerbosePreference = "Continue"
-$Module = Import-Module $PSScriptRoot\..\${ModuleName}.psd1 -Force -PassThru
-if ($null -eq $Module) {
-    Write-Error "Could not import $ModuleName"
-    exit 1
+    $VerbosePreference = "Continue"
+    $Module = Import-Module $PSScriptRoot\..\${ModuleName}.psd1 -Force -PassThru
+    if ($null -eq $Module) {
+        Write-Error "Could not import $ModuleName"
+        exit 1
+    }
+    Write-Host "Done."
+    Write-Host $Module.ExportedCommands.Values.Name
 }
-Write-Host "Done."
-Write-Host $Module.ExportedCommands.Values.Name
 
 Describe 'Confirm-FeatureFlagConfig' {
     Context 'Validation of invalid configuration' {
@@ -270,22 +272,24 @@ Describe 'Get-FeatureFlagConfigFromFile' {
 Describe 'Test-FeatureFlag' {
     Context 'allowlist condition' {
         Context 'Simple allowlist configuration' {
-            $serializedConfig = @"
-            {
-                "stages": {
-                    "all": [
-                        {"allowlist": [".*"]}
-                    ]
-                },
-                "features": {
-                    "well-tested": {
-                        "stages": ["all"]
+            BeforeAll {
+                $serializedConfig = @"
+                {
+                    "stages": {
+                        "all": [
+                            {"allowlist": [".*"]}
+                        ]
+                    },
+                    "features": {
+                        "well-tested": {
+                            "stages": ["all"]
+                        }
                     }
                 }
-            }
 "@
-            Confirm-FeatureFlagConfig $serializedConfig
-            $config = ConvertFrom-Json $serializedConfig
+                Confirm-FeatureFlagConfig $serializedConfig
+                $config = ConvertFrom-Json $serializedConfig
+            }
 
             It 'Rejects non-existing features' {
                 Test-FeatureFlag "feature1" "Storage/master" $config | Should -Be $false
@@ -297,25 +301,27 @@ Describe 'Test-FeatureFlag' {
         }
 
         Context 'Chained allowlist configuration' {
-            $serializedConfig = @"
-            {
-                "stages": {
-                    "test-repo-and-branch": [
-                        {"allowlist": [
-                            "storage1/.*",
-                            "storage2/dev-branch"
-                        ]}
-                    ]
-                },
-                "features": {
-                    "experimental-feature": {
-                        "stages": ["test-repo-and-branch"]
+            BeforeAll {
+                $serializedConfig = @"
+                {
+                    "stages": {
+                        "test-repo-and-branch": [
+                            {"allowlist": [
+                                "storage1/.*",
+                                "storage2/dev-branch"
+                            ]}
+                        ]
+                    },
+                    "features": {
+                        "experimental-feature": {
+                            "stages": ["test-repo-and-branch"]
+                        }
                     }
                 }
-            }
 "@
-            Confirm-FeatureFlagConfig $serializedConfig
-            $config = ConvertFrom-Json $serializedConfig
+                Confirm-FeatureFlagConfig $serializedConfig
+                $config = ConvertFrom-Json $serializedConfig
+            }
 
             It 'Returns true if the regex matches' {
                 Test-FeatureFlag "experimental-feature" "storage1/master" $config | Should -Be $true
@@ -330,22 +336,24 @@ Describe 'Test-FeatureFlag' {
 
     Context 'denylist condition' {
         Context 'Reject-all configuration' {
-            $serializedConfig = @"
-            {
-                "stages": {
-                    "none": [
-                        {"denylist": [".*"]}
-                    ]
-                },
-                "features": {
-                    "disabled": {
-                        "stages": ["none"]
+            BeforeAll {
+                $serializedConfig = @"
+                {
+                    "stages": {
+                        "none": [
+                            {"denylist": [".*"]}
+                        ]
+                    },
+                    "features": {
+                        "disabled": {
+                            "stages": ["none"]
+                        }
                     }
                 }
-            }
 "@
-            Confirm-FeatureFlagConfig $serializedConfig
-            $config = ConvertFrom-Json $serializedConfig
+                Confirm-FeatureFlagConfig $serializedConfig
+                $config = ConvertFrom-Json $serializedConfig
+            }
 
             It 'Rejects everything' {
                 Test-FeatureFlag "disabled" "Storage/master" $config | Should -Be $false
@@ -355,23 +363,25 @@ Describe 'Test-FeatureFlag' {
         }
 
         Context 'Reject single-value configuration' {
-            $serializedConfig = @"
-            {
-                "stages": {
-                    "all-except-important": [
-                        {"denylist": ["^important$"]}
-                    ]
-                },
-                "features": {
-                    "some-feature":
-                    {
-                        "stages": ["all-except-important"]
+            BeforeAll {
+                $serializedConfig = @"
+                {
+                    "stages": {
+                        "all-except-important": [
+                            {"denylist": ["^important$"]}
+                        ]
+                    },
+                    "features": {
+                        "some-feature":
+                        {
+                            "stages": ["all-except-important"]
+                        }
                     }
                 }
-            }
 "@
-            Confirm-FeatureFlagConfig $serializedConfig
-            $config = ConvertFrom-Json $serializedConfig
+                Confirm-FeatureFlagConfig $serializedConfig
+                $config = ConvertFrom-Json $serializedConfig
+            }
 
             # Given that the regex is ^important$, only the exact string "important" will match the denylist.
             It 'Allows the flag if the predicate does not match exactly' {
@@ -387,22 +397,24 @@ Describe 'Test-FeatureFlag' {
         }
 
         Context 'Reject multiple-value configuration' {
-            $serializedConfig = @"
-            {
-                "stages": {
-                    "all-except-important": [
-                        {"denylist": ["storage-important/master", "storage-important2/master"]}
-                    ]
-                },
-                "features": {
-                    "some-feature": {
-                        "stages": ["all-except-important"]
+            BeforeAll {
+                $serializedConfig = @"
+                {
+                    "stages": {
+                        "all-except-important": [
+                            {"denylist": ["storage-important/master", "storage-important2/master"]}
+                        ]
+                    },
+                    "features": {
+                        "some-feature": {
+                            "stages": ["all-except-important"]
+                        }
                     }
                 }
-            }
 "@
-            Confirm-FeatureFlagConfig $serializedConfig
-            $config = ConvertFrom-Json $serializedConfig
+                Confirm-FeatureFlagConfig $serializedConfig
+                $config = ConvertFrom-Json $serializedConfig
+            }
 
             It 'Allows predicates not matching the denylist' {
                 Test-FeatureFlag "some-feature" "storage1/master" $config | Should -Be $true
@@ -418,23 +430,25 @@ Describe 'Test-FeatureFlag' {
     }
 
     Context 'Mixed allowlist/denylist configuration' {
-        $serializedConfig = @"
-        {
-            "stages": {
-                "all-storage-important": [
-                    {"allowlist": ["storage.*"]},
-                    {"denylist": ["storage-important/master", "storage-important2/master"]}
-                ]
-            },
-            "features": {
-                "some-feature": {
-                    "stages": ["all-storage-important"]
+        BeforeAll {
+            $serializedConfig = @"
+            {
+                "stages": {
+                    "all-storage-important": [
+                        {"allowlist": ["storage.*"]},
+                        {"denylist": ["storage-important/master", "storage-important2/master"]}
+                    ]
+                },
+                "features": {
+                    "some-feature": {
+                        "stages": ["all-storage-important"]
+                    }
                 }
             }
-        }
 "@
-        Confirm-FeatureFlagConfig $serializedConfig
-        $config = ConvertFrom-Json $serializedConfig
+            Confirm-FeatureFlagConfig $serializedConfig
+            $config = ConvertFrom-Json $serializedConfig
+        }
 
         It 'Rejects storage important / important2 master branches' {
             Test-FeatureFlag "some-feature" "storage-important/master" $config | Should -Be $false
@@ -454,34 +468,36 @@ Describe 'Test-FeatureFlag' {
     }
 
     Context 'Probability condition' {
-        $serializedConfig = @"
-        {
-            "stages": {
-                "all": [
-                    {"probability": 1}
-                ],
-                "none": [
-                    {"probability": 0}
-                ],
-                "10percent": [
-                    {"probability": 0.1}
-                ]
-            },
-            "features": {
-                "well-tested": {
-                    "stages": ["all"]
+        BeforeAll {
+            $serializedConfig = @"
+            {
+                "stages": {
+                    "all": [
+                        {"probability": 1}
+                    ],
+                    "none": [
+                        {"probability": 0}
+                    ],
+                    "10percent": [
+                        {"probability": 0.1}
+                    ]
                 },
-                "not-launched": {
-                    "stages": ["none"]
-                },
-                "10pc-feature": {
-                    "stages": ["10percent"]
+                "features": {
+                    "well-tested": {
+                        "stages": ["all"]
+                    },
+                    "not-launched": {
+                        "stages": ["none"]
+                    },
+                    "10pc-feature": {
+                        "stages": ["10percent"]
+                    }
                 }
             }
-        }
 "@
-        Confirm-FeatureFlagConfig $serializedConfig
-        $config = ConvertFrom-Json $serializedConfig
+            Confirm-FeatureFlagConfig $serializedConfig
+            $config = ConvertFrom-Json $serializedConfig
+        }
 
         It 'Always allows with probability 1' {
             Test-FeatureFlag "well-tested" "storage-important/master" $config | Should -Be $true
@@ -523,25 +539,27 @@ Describe 'Test-FeatureFlag' {
     }
 
     Context 'Complex allowlist + denylist + probability configuration' {
-        $serializedConfig = @"
-        {
-            "stages": {
-                "all-storage-important-50pc": [
-                    {"allowlist": ["storage.*"]},
-                    {"denylist": ["storage-important/master", "storage-important2/master"]},
-                    {"probability": 0.5}
-                ]
-            },
-            "features": {
-                "some-feature": {
-                    "stages": ["all-storage-important-50pc"]
+        BeforeAll {
+            $serializedConfig = @"
+            {
+                "stages": {
+                    "all-storage-important-50pc": [
+                        {"allowlist": ["storage.*"]},
+                        {"denylist": ["storage-important/master", "storage-important2/master"]},
+                        {"probability": 0.5}
+                    ]
+                },
+                "features": {
+                    "some-feature": {
+                        "stages": ["all-storage-important-50pc"]
+                    }
                 }
             }
-        }
 "@
 
-        Confirm-FeatureFlagConfig $serializedConfig
-        $config = ConvertFrom-Json $serializedConfig
+            Confirm-FeatureFlagConfig $serializedConfig
+            $config = ConvertFrom-Json $serializedConfig
+        }
 
         It 'Rejects storage important / important2 master branches' {
             Test-FeatureFlag "some-feature" "storage-important/master" $config | Should -Be $false
@@ -571,10 +589,12 @@ Describe 'Test-FeatureFlag' {
 
 Describe 'Get-EvaluatedFeatureFlags' -Tag Features {
     Context 'Verify evaluation of all feature flags' {
-        $serializedConfig = Get-Content -Raw "$PSScriptRoot\multiple-stages-features.json"
-        Confirm-FeatureFlagConfig $serializedConfig
-        $config = ConvertFrom-Json $serializedConfig;
-        Mock New-Item -ModuleName FeatureFlags {}
+        BeforeAll {
+            $serializedConfig = Get-Content -Raw "$PSScriptRoot\multiple-stages-features.json"
+            Confirm-FeatureFlagConfig $serializedConfig
+            $config = ConvertFrom-Json $serializedConfig;
+            Mock New-Item -ModuleName FeatureFlags {}
+        }
 
         It 'Returns expected feature flags' {
             $expected = @{ "filetracker"=$true; "newestfeature"=$true; "testfeature"=$false }
@@ -587,20 +607,22 @@ Describe 'Get-EvaluatedFeatureFlags' -Tag Features {
 
 Describe 'Out-EvaluatedFeaturesFiles' -Tag Features {
     Context 'Verify output file content' {
-        $global:featuresJsonContent = New-Object 'System.Collections.ArrayList()'
-        $global:featuresIniContent = New-Object 'System.Collections.ArrayList()'
-        $global:featuresEnvConfigContent = New-Object 'System.Collections.ArrayList()'
+        BeforeAll {
+            $global:featuresJsonContent = New-Object 'System.Collections.ArrayList()'
+            $global:featuresIniContent = New-Object 'System.Collections.ArrayList()'
+            $global:featuresEnvConfigContent = New-Object 'System.Collections.ArrayList()'
 
-        $serializedConfig = Get-Content -Raw "$PSScriptRoot\multiple-stages-features.json"
-        Confirm-FeatureFlagConfig $serializedConfig
-        $config = ConvertFrom-Json $serializedConfig
+            $serializedConfig = Get-Content -Raw "$PSScriptRoot\multiple-stages-features.json"
+            Confirm-FeatureFlagConfig $serializedConfig
+            $config = ConvertFrom-Json $serializedConfig
 
-        Mock -ModuleName FeatureFlags New-Item {}
-        Mock -ModuleName $ModuleName Test-Path { Write-Output $true }
-        Mock -ModuleName $ModuleName Remove-Item {}
-        Mock -ModuleName $ModuleName Out-File { ${global:featuresJsonContent}.Add($InputObject) } -ParameterFilter { $FilePath.EndsWith("features.json") }
-        Mock -ModuleName $ModuleName Add-Content { ${global:featuresIniContent}.Add($Value) } -ParameterFilter  { $Path.EndsWith("features.ini") }
-        Mock -ModuleName $ModuleName Add-Content { ${global:featuresEnvConfigContent}.Add($Value) } -ParameterFilter { $Path.EndsWith("features.env.config") }
+            Mock -ModuleName FeatureFlags New-Item {}
+            Mock -ModuleName $ModuleName Test-Path { Write-Output $true }
+            Mock -ModuleName $ModuleName Remove-Item {}
+            Mock -ModuleName $ModuleName Out-File { ${global:featuresJsonContent}.Add($InputObject) } -ParameterFilter { $FilePath.EndsWith("features.json") }
+            Mock -ModuleName $ModuleName Add-Content { ${global:featuresIniContent}.Add($Value) } -ParameterFilter  { $Path.EndsWith("features.ini") }
+            Mock -ModuleName $ModuleName Add-Content { ${global:featuresEnvConfigContent}.Add($Value) } -ParameterFilter { $Path.EndsWith("features.env.config") }
+        }
 
         It 'Honors denylist' {
             $features = Get-EvaluatedFeatureFlags -predicate "important" -config $config
@@ -627,5 +649,7 @@ Describe 'Out-EvaluatedFeaturesFiles' -Tag Features {
     }
 }
 
-Remove-Module $ModuleName
-Remove-Module test-functions
\ No newline at end of file
+AfterAll {
+    Remove-Module $ModuleName
+    Remove-Module test-functions
+}
\ No newline at end of file
diff --git a/test/test-functions.psm1 b/test/test-functions.psm1
index d7ba745..d30554c 100644
--- a/test/test-functions.psm1
+++ b/test/test-functions.psm1
@@ -22,7 +22,7 @@ Function Test-StringArrays
 
     if ($null -eq $Actual)
     {
-        $Expected | Should Be $null
+        $Expected | Should -Be $null
         return
     }
 
@@ -38,11 +38,11 @@ Function Test-StringArrays
         Write-Host "Expected: $Expected" -ForegroundColor Red
     }
 
-    $Actual.Count | Should Be $Expected.Count
+    $Actual.Count | Should -Be $Expected.Count
 
     for ($i = 0; $i -lt $Actual.Count; $i++)
     {
-        $Actual[$i] | Should Be $Expected[$i]
+        $Actual[$i] | Should -Be $Expected[$i]
     }
 }
 
@@ -68,7 +68,7 @@ Function Test-ObjectArrays
 
     if ($Actual -eq $null)
     {
-        $Expected | Should Be $null
+        $Expected | Should -Be $null
         return
     }
 
@@ -84,7 +84,7 @@ Function Test-ObjectArrays
         Write-Host "Expected: $Expected" -ForegroundColor Red
     }
 
-    $Actual.Count | Should Be $Expected.Count
+    $Actual.Count | Should -Be $Expected.Count
 
     for ($i = 0; $i -lt $Actual.Count; $i++)
     {
@@ -114,13 +114,13 @@ Function Test-Hashtables
 
     if ($Expected -eq $null)
     {
-        $Actual | Should Be $null
+        $Actual | Should -Be $null
         return
     }
 
     if ($Actual -eq $null)
     {
-        $Expected | Should Be $null
+        $Expected | Should -Be $null
         return
     }
 
@@ -129,7 +129,7 @@ Function Test-Hashtables
         # Redundant, but tells Pester we tested something
         # If the counts don't match, continue with the comparison so we contain
         # find out what's missing in the test error log
-        $Actual.Count | Should Be $Expected.Count
+        $Actual.Count | Should -Be $Expected.Count
         return
     }
 
@@ -141,11 +141,11 @@ Function Test-Hashtables
 
             if ($null -eq $actualProperty.Value)
             {
-                $actualProperty.Value | Should Be $expectedValue
+                $actualProperty.Value | Should -Be $expectedValue
             }
             else
             {
-                $actualProperty.Value.GetType() | Should Be $expectedValue.GetType()
+                $actualProperty.Value.GetType() | Should -Be $expectedValue.GetType()
 
                 if ($expectedValue.GetType().FullName -eq 'System.Collections.Hashtable')
                 {
@@ -164,12 +164,12 @@ Function Test-Hashtables
                     else
                     {
                         # Just assert their lengths for now
-                        $actualProperty.Value.Count | Should Be $expectedValue.Count    
+                        $actualProperty.Value.Count | Should -Be $expectedValue.Count    
                     }
                 }
                 else
                 {
-                    $actualProperty.Value | Should Be $expectedValue
+                    $actualProperty.Value | Should -Be $expectedValue
                 }   
             }
         }
@@ -187,11 +187,11 @@ Function Test-Hashtables
 
             if ($null -eq $expectedProperty.Value)
             {
-                $actualValue | Should Be $expectedProperty.Value
+                $actualValue | Should -Be $expectedProperty.Value
             }
             else
             {
-                $actualValue.GetType() | Should Be $expectedProperty.Value.GetType()
+                $actualValue.GetType() | Should -Be $expectedProperty.Value.GetType()
 
                 if ($expectedProperty.Value.GetType().FullName -eq 'System.Collections.Hashtable')
                 {
@@ -210,12 +210,12 @@ Function Test-Hashtables
                     else
                     {
                         # Just assert their lengths for now
-                        $actualValue.Count | Should Be $expectedProperty.Value.Count    
+                        $actualValue.Count | Should -Be $expectedProperty.Value.Count    
                     }
                 }
                 else
                 {
-                    $actualValue | Should Be $expectedProperty.Value
+                    $actualValue | Should -Be $expectedProperty.Value
                 }
             }
         }
diff --git a/tools/run-tests.ps1 b/tools/run-tests.ps1
index 4df9c83..7d063ba 100644
--- a/tools/run-tests.ps1
+++ b/tools/run-tests.ps1
@@ -1,17 +1,27 @@
 # Mostly for use of CI/CD. Install Pester and run tests.
+param (
+  # Set to true to install Pester 5.1.0, regardless of whether a Pester version
+  # is present in the environment.
+  [switch] $InstallPester = $false
+)
+
 $parentDir = Split-Path -Parent (Split-Path -Parent $PSCommandPath)
 $testDir = Join-Path $parentDir -ChildPath "test"
 
 # Debug info.
 $PSVersionTable | Out-String
 
-Write-Host "Checking for Pester > 4.0.0..."
-$pester = Get-Module -ListAvailable | Where-Object {$_.Name -eq "Pester" -and $_.Version -gt '4.0.0'}
-if ($pester.Count -eq 0) {
-    Write-Host "Cannot find the Pester module. Installing it."
-    Install-Module Pester -Force -Scope CurrentUser -RequiredVersion 4.10.1
-} else {
-    Write-Host "Found Pester version $($pester.Version)."
+# List Pester versions.
+$pesterVersions = Get-Module -ListAvailable | Where-Object {$_.Name -eq "Pester" }
+$pesterVersions | % { Write-Host $_.Name $_.Version }
+
+if ($pesterVersions.Count -eq 0) {
+   Write-Warning "No Pester found, will install Pester 5.1.0"
+   $InstallPester = $true
+}
+
+if ($InstallPester) {
+   Install-Module Pester -Force -Scope CurrentUser -RequiredVersion 5.1.0
 }
 
 $FailedTests = Invoke-Pester $testDir -EnableExit -OutputFile "test/results.xml" -OutputFormat "NUnitXML" -CodeCoverage "$parentDir/FeatureFlags.psm1"