maester-test-expert

name

maester-test-expert

description

Write, validate, and document Maester security checks for Microsoft 365 tenants. Use when asked to create, edit, review, or debug a Maester Pester test file, its companion markdown documentation, or its tagging. Covers Graph API data retrieval, Add-MtTestResultDetail formatting, the tagging taxonomy (CIS, CISA, EIDSCA, ORCA, MT), helper function patterns, remediation guidance, Entra ID, Exchange, SharePoint, Teams, Defender, Conditional Access, and the validation checklist for new checks.

Maester Test Expert

Create, edit, validate, and document Maester security checks -- the unit of work that assesses a Microsoft 365 tenant's security posture.

Agent Selection

Use maester-test-expert as the primary agent for all normal workflows.

Specialized planner and issue-manager agents are optional workflow components and should generally stay in the background to avoid user confusion.

When to Use This Skill

Activate this skill when the task involves any of the following:

• Creating a new Maester security check (test file + helper function + documentation)
• Editing or refactoring an existing check
• Adding or correcting tags on a test
• Writing or updating the companion markdown documentation for a check
• Writing or updating the website documentation page for a check
• Reviewing a check for correctness, tagging compliance, or documentation completeness
• Debugging a failing Maester test
• Understanding how Maester tests retrieve data from the Microsoft Graph API

Do NOT use this skill for:

• EIDSCA tests -- these are auto-generated from the build/eidsca/ pipeline. Do not edit tests/EIDSCA/Test-EIDSCA.Generated.Tests.ps1 by hand.
• ORCA tests -- these are auto-generated from the build/orca/ pipeline. Do not edit files in tests/orca/ by hand.
• General Pester questions unrelated to the Maester framework.

Prerequisites

• The Maester PowerShell module installed.
• Familiarity with Pester v5 test structure (Describe, Context, It, BeforeAll, BeforeDiscovery).
• A working Connect-Maester session for local testing.
• Review the Maester contribution guidelines before submitting changes.

Anatomy of a Maester Check

A Maester check is a unit of work consisting of up to four coordinated files. Simple custom tests may use only one file; checks contributed to the project typically use all four.

1. Test File (.Tests.ps1)

Location: tests/{Suite}/{Area}/ (e.g., tests/Maester/Entra/, tests/CISA/entra/, tests/CIS/)

The Pester test file that orchestrates execution. It calls a helper function, asserts the result, and carries tags for filtering.

2. Helper Function (.ps1)

Location: powershell/public/{suite}/{area}/ (e.g., powershell/public/cisa/entra/, powershell/public/maester/entra/)

A PowerShell function that retrieves data (usually via Graph API), evaluates the tenant configuration, formats a result with Add-MtTestResultDetail, and returns $true, $false, or $null.

3. Companion Markdown (.md) -- Helper Documentation

Location: Same directory and same base name as the helper function (e.g., powershell/public/cisa/entra/Test-MtCisaWeakFactor.md alongside Test-MtCisaWeakFactor.ps1).

Provides the description, rationale, remediation steps, and reference links shown in the test report. Ends with a %TestResult% placeholder.

4. Website Documentation Page (MT.XXXX.md)

Location: website/docs/tests/maester/ (e.g., website/docs/tests/maester/MT.1001.md)

The public documentation page on maester.dev with YAML frontmatter, a description, step-by-step remediation, and reference links.

Simple Custom Tests (Single-File Pattern)

For quick custom checks (in the tests/Custom/ directory), all logic and formatting can live in one .Tests.ps1 file. No separate helper function or companion markdown is required. See the "Custom Test Template" below.

---

Test File (.Tests.ps1)

Naming Convention

Suite	Pattern	Example
Maester	Test-{Feature}.Tests.ps1 or Test-Mt{Feature}.Tests.ps1	Test-AppManagementPolicies.Tests.ps1
CISA	Test-MtCisa{Control}.Tests.ps1	Test-MtCisaWeakFactor.Tests.ps1
CIS	Test-MtCis{Control}.Tests.ps1	Test-MtCisGlobalAdminCount.Tests.ps1

The .Tests.ps1 suffix is mandatory -- Pester uses it for automatic test discovery.

Pester Structure

Every test file follows this pattern:

Describe "{Suite/Area}" -Tag "{SuiteTag}", "{ProductAreaTag}" {
    It "{TestID}: {Description}. See https://maester.dev/docs/tests/{TestID}" -Tag "{TestID}" {
        $result = {HelperFunction}

        if ($null -ne $result) {
            $result | Should -Be $true -Because "{explanation of expected state}"
        }
    }
}

Key rules:

• The Describe block title identifies the suite and area (e.g., "Maester/Entra", "CISA", "CIS").
• The Describe block -Tag carries the test suite tag (exactly one) and product area tags (1-3).
• The It block title starts with the test ID followed by a colon, then a human-readable description with a See link to the docs page.
• The It block -Tag carries only the test ID (e.g., "MT.1024").
• The null check pattern (if ($null -ne $result)) ensures that when a helper returns $null (meaning it was skipped), the assertion is not evaluated and the test is reported as skipped rather than failed.

Real Example -- Simple Maester Test

From tests/Maester/Entra/Test-AppManagementPolicies.Tests.ps1:

Describe "Maester/Entra" -Tag "Maester", "App" {
    It "MT.1002: App management restrictions on applications and service principals is configured and enabled. See https://maester.dev/docs/tests/MT.1002" -Tag "MT.1002" {

        Test-MtAppManagementPolicyEnabled | Should -Be $true -Because "an app policy for workload identities should be defined to enforce strong credentials instead of passwords and a maximum expiry period (e.g. credential should be renewed every six months)"
    }
}

Real Example -- CISA Test with Null Check

From tests/CISA/entra/Test-MtCisaWeakFactor.Tests.ps1:

Describe "CISA" -Tag "MS.AAD", "MS.AAD.3.5", "CISA.MS.AAD.3.5", "CISA", "Entra ID P1" {
    It "CISA.MS.AAD.3.5: The authentication methods SMS, Voice Call, and Email One-Time Passcode (OTP) SHALL be disabled." {
        $result = Test-MtCisaWeakFactor

        if ($null -ne $result) {
            $result | Should -Be $true -Because "all weak authentication methods are disabled."
        }
    }
}

Real Example -- CIS Test

From tests/CIS/Test-MtCisGlobalAdminCount.Tests.ps1:

Describe "CIS" -Tag "CIS.M365.1.1.3", "L1", "CIS E3 Level 1", "CIS E3", "CIS", "CIS M365 v5.0.0" {
    It "CIS.M365.1.1.3: Ensure that between two and four global admins are designated" {

        $result = Test-MtCisGlobalAdminCount

        if ($null -ne $result) {
            $result | Should -Be $true -Because "only 2-4 Global Administrators exist"
        }
    }
}

Advanced Pattern -- Parameterized Tests with BeforeDiscovery

Some checks generate dynamic tests from data discovered at parse time. This pattern is used for health issues, per-user evaluations, and similar scenarios.

BeforeDiscovery {
    $Items = Invoke-MtGraphRequest -RelativeUri "some/endpoint" -ApiVersion beta
    # Process and group items as needed
}

Describe "Maester/Area" -Tag "Maester", "ProductArea" -ForEach $Items {
    It "MT.XXXX: {Description} - $($_.Name)" -Tag "MT.XXXX" {
        $_.status | Should -Be "healthy" -Because "all items should be in a healthy state"
    }
}

Advanced Pattern -- Conditional Execution (License/Connection Gating)

Tests that require specific licenses or service connections use -Skip on the It block:

BeforeDiscovery {
    $EntraIDPlan = Get-MtLicenseInformation -Product 'EntraID'
}

Describe "Maester/Entra" -Tag "Maester", "Entra" {
    It "MT.XXXX: {Description}" -Tag "MT.XXXX" -Skip:($EntraIDPlan -eq "Free") {
        # Test logic -- only runs if Entra ID P1 or P2 is available
    }
}

---

Helper Function (.ps1)

Naming Convention

• Maester suite: Test-Mt{Feature}.ps1 (e.g., Test-MtAppManagementPolicyEnabled.ps1)
• CISA suite: Test-MtCisa{Control}.ps1 (e.g., Test-MtCisaWeakFactor.ps1)
• CIS suite: Test-MtCis{Control}.ps1 (e.g., Test-MtCisGlobalAdminCount.ps1)

Directory Placement

Suite	Directory
Maester	powershell/public/maester/{area}/ (e.g., entra/, exchange/, teams/, azure/)
CISA	powershell/public/cisa/{area}/ (e.g., entra/, exchange/, spo/)
CIS	powershell/public/cis/

Structure Template

function Test-Mt{Name} {
    <#
    .SYNOPSIS
    {One-line summary of what the check verifies}

    .DESCRIPTION
    {Detailed description of the security control being evaluated}

    .EXAMPLE
    Test-Mt{Name}

    Returns true if {condition is met}

    .LINK
    https://maester.dev/docs/commands/Test-Mt{Name}
    #>
    [CmdletBinding()]
    [OutputType([bool])]
    param()

    # 1. Connection check
    if (!(Test-MtConnection Graph)) {
        Add-MtTestResultDetail -SkippedBecause NotConnectedGraph
        return $null
    }

    # 2. License check (if applicable)
    $EntraIDPlan = Get-MtLicenseInformation -Product EntraID
    if ($EntraIDPlan -eq "Free") {
        Add-MtTestResultDetail -SkippedBecause NotLicensedEntraIDP1
        return $null
    }

    try {
        # 3. Retrieve data
        $data = Invoke-MtGraphRequest -RelativeUri "endpoint"

        # 4. Evaluate configuration
        $testResult = ($data.someProperty -eq $expectedValue)

        # 5. Format result markdown
        if ($testResult) {
            $testResultMarkdown = "Well done. {Positive outcome description.}"
        } else {
            $testResultMarkdown = "{Negative outcome description with actionable detail.}"
        }

        # 6. Report result (omit -Description to use companion .md file)
        Add-MtTestResultDetail -Result $testResultMarkdown

        return $testResult
    } catch {
        Add-MtTestResultDetail -SkippedBecause Error -SkippedError $_
        return $null
    }
}

Key Patterns

Connection Checks

Always verify the required service connection before making API calls:

# Microsoft Graph
if (!(Test-MtConnection Graph)) {
    Add-MtTestResultDetail -SkippedBecause NotConnectedGraph
    return $null
}

# Microsoft Teams
if (!(Test-MtConnection Teams)) {
    Add-MtTestResultDetail -SkippedBecause NotConnectedTeams
    return $null
}

# Application permissions not supported
if (((Get-MgContext).AuthType) -ne "Delegated") {
    Add-MtTestResultDetail -SkippedBecause 'NotSupportedAppPermission'
    return $null
}

Data Retrieval with Invoke-MtGraphRequest

Always prefer Invoke-MtGraphRequest over Invoke-MgGraphRequest or Get-Mg* cmdlets. It provides:

• Built-in caching -- reduces API calls when multiple tests query the same endpoint.
• Automatic pagination -- no need for -All.
• ConsistencyLevel header -- included by default for read-only calls.
• Batching -- pass an array of IDs via -UniqueId for automatic batch optimization.
• Named parameters -- Select, Filter, QueryParameters for cleaner code.

# Simple query
$policies = Invoke-MtGraphRequest -RelativeUri "policies/authorizationPolicy" -ApiVersion v1.0

# With filter and select
$users = Invoke-MtGraphRequest -RelativeUri "users" -Filter "userType eq 'Member'" -Select id, displayName

# Batch by IDs
$users = Invoke-MtGraphRequest -RelativeUri "users" -UniqueId $userIds -Select id, displayName, onPremisesSyncEnabled

# Complex query with splatting
$policySplat = @{
    ApiVersion      = "beta"
    RelativeUri     = "policies/roleManagementPolicyAssignments"
    Filter          = "scopeId eq '/' and scopeType eq 'DirectoryRole' and roleDefinitionId eq '$($role.id)'"
    QueryParameters = @{
        expand = "policy(expand=rules)"
    }
}
$policy = Invoke-MtGraphRequest @policySplat

Result Formatting

Use Add-MtTestResultDetail to provide rich test output:

# Basic result text (companion .md provides the description)
Add-MtTestResultDetail -Result $resultMarkdown

# With description (when no companion .md exists)
Add-MtTestResultDetail -Description "What the test checks" -Result "The outcome"

# With Graph objects (creates deep links to admin portal)
Add-MtTestResultDetail -Result "Found issues:`n`n%TestResult%" -GraphObjects $failingPolicies -GraphObjectType ConditionalAccess

# Marking a result for manual review
Add-MtTestResultDetail -Description $description -Result $result -Investigate

# Custom skipped reason
Add-MtTestResultDetail -SkippedBecause Custom -SkippedCustomReason "All alerts have been suppressed"

Supported -GraphObjectType values: Users, Groups, Devices, ConditionalAccess, AuthenticationMethod, AuthorizationPolicy, ConsentPolicy, Domains, IdentityProtection, UserRole.

When using -GraphObjects, the -Result string must include %TestResult% at the position where the object list will be inserted.

Error Handling

Critical rule: Wrap the main logic in try/catch. In the catch block, call Add-MtTestResultDetail -SkippedBecause Error and return $null.

try {
    # Main test logic here
} catch {
    Add-MtTestResultDetail -SkippedBecause Error -SkippedError $_
    return $null
}

Do NOT call Add-MtTestResultDetail -SkippedBecause inside the try block. This causes the test to be reported as errored instead of skipped. Close the try block first, then call the skip method, then start a new try block if needed.

Module Registration

After creating a new helper function, add the function name to the FunctionsToExport array in powershell/Maester.psd1.

---

Companion Markdown (.md) -- Helper Documentation

This file provides the description shown in the Maester test report. It has no YAML frontmatter.

Location and Naming

Place the .md file in the same directory as the helper function, with the same base name:

powershell/public/cisa/entra/Test-MtCisaWeakFactor.ps1   ← helper function
powershell/public/cisa/entra/Test-MtCisaWeakFactor.md    ← companion doc

Template

{One-line summary of what the check verifies.}

{Rationale: explain WHY this configuration matters for security.}

#### Remediation action:

1. In **Entra ID**, navigate to **{Section}** > **[{Page Name}]({direct admin portal URL})**.
2. {Step-by-step instructions to fix the issue.}
3. Click **Save**.

#### Related links

* [{Admin portal link description}]({URL})
* [{Benchmark or baseline reference}]({URL})

<!--- Results --->
%TestResult%

Key Rules

• The %TestResult% placeholder at the end is mandatory. It is replaced at runtime with the formatted test output.
• The <!--- Results ---> HTML comment before the placeholder is conventional but optional.
• Omit the -Description parameter when calling Add-MtTestResultDetail in the helper so that the companion .md content is used as the description automatically.
• Include direct links to the relevant admin portal blade (Entra, Exchange, SharePoint, etc.) so the reader can navigate directly to the configuration.

Real Example

From powershell/public/cisa/entra/Test-MtCisaWeakFactor.md:

The authentication methods SMS, Voice Call, and Email One-Time Passcode (OTP) SHALL be disabled.

Rationale: SMS, voice call, and email OTP are the weakest authenticators. This policy forces users to use stronger MFA methods.

#### Remediation action:

1. In **Entra ID**, click **Security** > **[Authentication methods](https://entra.microsoft.com/#view/Microsoft_AAD_IAM/AuthenticationMethodsMenuBlade/~/AdminAuthMethods/fromNav/Identity)**
2. Click on the **SMS**, **Voice Call**, and **Email OTP** authentication methods and disable each of them.

#### Related links

* [Entra admin portal - Authentication methods](https://entra.microsoft.com/#view/Microsoft_AAD_IAM/AuthenticationMethodsMenuBlade/~/AdminAuthMethods/fromNav/Identity)
* [CISA Strong Authentication & Secure Registration - MS.AAD.3.5v1](https://github.com/cisagov/ScubaGear/blob/main/PowerShell/ScubaGear/baselines/aad.md#msaad35v1)

<!--- Results --->
%TestResult%

---

Website Documentation Page (MT.XXXX.md)

This is the public documentation page hosted on maester.dev.

Location

website/docs/tests/maester/MT.XXXX.md (replace XXXX with the test ID number).

Template

---
title: MT.XXXX - {Short title}
description: {One-line description}
slug: /tests/MT.XXXX
sidebar_class_name: hidden
---

# {Short title}

## Description

{Detailed description of what the check verifies and why it matters.}

## How to fix

{Step-by-step remediation instructions.}

1. Sign in to the [Microsoft Entra admin center](https://entra.microsoft.com) as at least a {minimum required role}.
2. Browse to **{Section}** > **{Page}**.
3. {Specific configuration steps.}
4. Select **Save**.

## Learn more

- [{Reference title}]({URL})
- [{Admin portal link}]({URL})

Frontmatter Fields

Field	Required	Description
title	Yes	MT.XXXX - {Short title}
description	Yes	One-line description of the check
slug	Yes	/tests/MT.XXXX
sidebar_class_name	Yes	Always hidden

Real Example

From website/docs/tests/maester/MT.1001.md:

---
title: MT.1001 - At least one Conditional Access policy is configured with device compliance
description: Device compliance conditional access policy can be used to require devices to be compliant with the tenant's security configuration.
slug: /tests/MT.1001
sidebar_class_name: hidden
---

# At least one Conditional Access policy is configured with device compliance

## Description

Device compliance conditional access policy can be used to require devices to be compliant with the tenant's security configuration.

## How to fix

Create a conditional access policy that requires devices to have device compliance.

1. Sign in to the [Microsoft Entra admin center](https://entra.microsoft.com) as at least a Conditional Access Administrator.
2. Browse to **Protection** > **Conditional Access** > **Policies**.
3. Select **New policy**.
4. Give your policy a name.
5. Under **Assignments**, select **Users or workload identities**.
    - Under **Target resources** > **Resources (formerly cloud apps)** > **Include**, select **All resources (formerly 'All cloud apps')**.
6. Under **Access controls** > **Grant**.
    - Select **Require device to be marked as compliant** and **Require Microsoft Entra hybrid joined device**
    - **For multiple controls** select **Require one of the selected controls**.
    - Select **Select**
8. Confirm your settings and set **Enable policy** to **Enable**
9. Select **Create** to create to enable your policy.

## Related links
- [Entra admin center - Conditional Access | Policies](https://entra.microsoft.com/#view/Microsoft_AAD_ConditionalAccess/ConditionalAccessBlade/~/Overview/fromNav/)

---

Tagging Taxonomy

Tags identify, group, and filter tests during execution. Follow these rules strictly.

Three Tag Categories

1. Test Suite (Required -- Exactly One)

Identifies which benchmark or baseline the test aligns with. This tag goes in the Describe block.

Suite	Tag Format	Examples
Maester	Maester	"Maester"
CISA	CISA + control ID tags	"CISA", "MS.AAD.3.5", "CISA.MS.AAD.3.5"
CIS	CIS + benchmark tags	"CIS", "CIS.M365.1.1.3", "CIS M365 v5.0.0"
EIDSCA	EIDSCA + control ID	"EIDSCA", "EIDSCA.AP01"
ORCA	ORCA + control ID	"ORCA", "ORCA.100"

2. Product Area (Required -- 1 to 3 tags)

Identifies which Microsoft 365 products or services are tested. These tags also go in the Describe block.

Valid Product Area Tags
Azure
Defender XDR
Entra
Exchange
Microsoft 365
SharePoint
Teams

3. Practice / Capability (Optional -- Use Sparingly)

Denotes a specific security practice. Only add when it provides significant categorization value. Avoid creating single-use tags.

Valid Practice Tags
Authentication
CA (Conditional Access)
DLP (Data Loss Prevention)
XSPM (Extended Security Posture Management)
Hybrid Identity
PAM (Privileged Access Management)
PIM (Privileged Identity Management)

Special Tags

Tag	Purpose
LongRunning	Marks tests that may take significant time in large tenants. Excluded by default; included via Invoke-Maester -IncludeLongRunning.
Preview	Marks tests that depend on preview APIs or are still being validated. Excluded by default; included via Invoke-Maester -IncludePreview.
Severity:{Level}	Optionally set on It blocks. Valid levels: Critical, High, Medium, Low, Info, and Investigate. The preferred location to set these is in maester-config.json.
License	Used to tag license-related tests.

Deprecated Tags -- Do NOT Use

Deprecated Tag	Replacement
All	Removed. Use Invoke-Maester -IncludePreview instead.
Full	Removed. Use Invoke-Maester -IncludeLongRunning instead.

Tag Placement Summary

Describe "Maester/Entra" -Tag "Maester", "Entra", "CA" {
#                              ↑ Suite     ↑ Product  ↑ Practice (optional)
    It "MT.1001: Description" -Tag "MT.1001", "Severity:High" {
    #                               ↑ Test ID    ↑ Severity (optional)
    }
}

---

Step-by-Step Workflow: Creating a New Check

Follow these steps to create a complete Maester check contributed to the project.

Step 1: Reserve a Test ID

Check GitHub issue #697 to see which test numbers have been used. Comment on the issue to reserve your ID (e.g., MT.1123).

Step 2: Determine File Locations

Based on the suite and product area:

• Test file: tests/Maester/{Area}/Test-Mt{Feature}.Tests.ps1
• Helper function: powershell/public/maester/{area}/Test-Mt{Feature}.ps1
• Companion doc: powershell/public/maester/{area}/Test-Mt{Feature}.md
• Website doc: website/docs/tests/maester/MT.XXXX.md

Step 3: Write the Helper Function

Create the .ps1 file following the helper function template above. Ensure:

1. Connection check is first.
2. License check follows (if the check requires P1/P2).
3. Data retrieval uses Invoke-MtGraphRequest.
4. Result formatting uses Add-MtTestResultDetail.
5. Error handling wraps everything in try/catch.
6. Function returns $true, $false, or $null.

Step 4: Write the Companion Markdown

Create the .md file alongside the helper. Include:

1. One-line summary.
2. Rationale.
3. Numbered remediation steps with admin portal links.
4. Related reference links.
5. The %TestResult% placeholder at the end.

Step 5: Write the Test File

Create the .Tests.ps1 file following the test file template. Ensure:

1. Describe block has exactly one suite tag and 1-3 product area tags.
2. It block title starts with the test ID and includes a See link to the docs page.
3. It block -Tag includes the test ID.
4. The null check pattern wraps the assertion.
5. The -Because message explains the expected state clearly.

Step 6: Write the Website Documentation

Create the MT.XXXX.md file with YAML frontmatter and the standard sections (Description, How to fix, Learn more).

Step 7: Register the Function

Add the helper function name to the FunctionsToExport array in powershell/Maester.psd1.

Step 8: Validate

Run the validation checklist below.

---

Custom Test Template (Single-File Pattern)

For checks that live in tests/Custom/ and do not need a separate helper function:

Describe "ContosoEntraConfig" -Tag "Entra" {
    It "CT.0001: {Description}" -Tag "CT.0001", "Severity:Medium" {

        try {
            # Retrieve data
            $data = Invoke-MtGraphRequest -RelativeUri "endpoint"

            # Evaluate
            $failing = $data | Where-Object { $_.Property -ne $ExpectedValue }

            # Format results
            $testDescription = "Checks if {what is being checked}."
            if ($failing.Count -gt 0) {
                $result = "Found $($failing.Count) items not meeting the requirement.`n`n%TestResult%"
                Add-MtTestResultDetail -Description $testDescription -Result $result -GraphObjects $failing -GraphObjectType ConditionalAccess
            } else {
                Add-MtTestResultDetail -Description $testDescription -Result "Well done. All items meet the requirement."
            }

            $failing.Count | Should -Be 0 -Because "{explanation}"
        } catch {
            Add-MtTestResultDetail -SkippedBecause Error -SkippedError $_
            return $null
        }
    }
}

---

Validation Checklist

Before submitting a new or updated check, verify every item:

Test Logic

• Helper function returns $true when the check passes, $false when it fails, and $null when it is skipped.
• Connection check (Test-MtConnection) is the first operation in the helper.
• License check (Get-MtLicenseInformation) is present if the check requires Entra ID P1/P2.
• Data retrieval uses Invoke-MtGraphRequest (not Invoke-MgGraphRequest or Get-Mg* cmdlets) for caching benefits.
• No hardcoded values -- GUIDs, tenant IDs, or user-specific data must be parameterized or discovered.
• Error handling: main logic is wrapped in try/catch; catch block calls Add-MtTestResultDetail -SkippedBecause Error -SkippedError $_ and returns $null.
• No Add-MtTestResultDetail -SkippedBecause calls inside a try block.

Test File

• File name ends with .Tests.ps1.
• Describe block has exactly one test suite tag.
• Describe block has 1-3 product area tags.
• It block title starts with the test ID followed by a colon.
• It block -Tag includes the test ID.
• Null check pattern wraps the Should assertion.
• -Because message is clear, specific, and actionable.

Tags

• No deprecated tags (All, Full).
• Practice/capability tags are used sparingly (0-1 per test in most cases).
• LongRunning tag is applied if the test may be slow in large tenants.
• Preview tag is applied if the test depends on preview/beta APIs.
• Tags are consistent with the tag taxonomy.

Documentation

• Companion .md file exists alongside the helper function.
• Companion .md ends with %TestResult%.
• Companion .md includes remediation steps with admin portal links.
• Website doc MT.XXXX.md exists with correct YAML frontmatter.
• Website doc includes Description, How to fix, and Learn more sections.
• Test ID is consistent across the test file name/tags, companion doc, and website doc.

Output Messages

• Pass message starts with "Well done." and describes the positive outcome.
• Fail message clearly states what is wrong and what needs to change.
• Markdown tables use proper formatting (headers, separators, rows).
• Admin portal deep links are included where applicable.

Code Style

• One True Brace Style (OTBS) -- opening brace on the same line.
• Pascal Case for variables and function names.
• Full cmdlet names -- no aliases (e.g., Where-Object not ? or where).
• Comment-based help is inside the function block with .SYNOPSIS, .DESCRIPTION, .EXAMPLE, and .LINK.
• [CmdletBinding()] and [OutputType([bool])] are declared.
• File encoding is UTF-8 with BOM (UTF8BOM).

Pre-Pull Request

• Helper function name is added to FunctionsToExport in powershell/Maester.psd1.
• Local tests pass: run powershell/tests/pester.ps1.
• PSScriptAnalyzer shows no warnings.
• Commit messages follow Conventional Commits.

---

Common Mistakes

Mistake	Why It Matters	Fix
Using Invoke-MgGraphRequest or Get-Mg* cmdlets instead of Invoke-MtGraphRequest	Bypasses caching -- tests become slow and make redundant API calls	Replace with Invoke-MtGraphRequest
Missing the null check pattern around Should	A skipped test ($null) is reported as a failure instead	Wrap assertion in if ($null -ne $result) { ... }
Calling Add-MtTestResultDetail -SkippedBecause inside a try block	Test is reported as errored instead of skipped	Move the call outside the try block
Hardcoded GUIDs or tenant-specific values	Test fails in every other tenant	Discover values dynamically via Graph API
Using deprecated tags All or Full	These tags no longer work; tests will not be properly filtered	Use LongRunning or Preview tags; users run them via -IncludeLongRunning or -IncludePreview switches
Over-tagging with many practice/capability tags	Increases noise; makes tag filtering less useful	Limit to 1 practice tag maximum per test, only when it adds clear value
Creating a test without its companion .md	Test report shows no description or remediation guidance	Always create the .md file alongside the helper
Creating a helper without adding it to FunctionsToExport	Function is not exported from the module and cannot be called	Add to the array in powershell/Maester.psd1
Missing connection or license checks	Test throws an unhandled error when the service is not connected	Add Test-MtConnection and Get-MtLicenseInformation checks before any API calls
Omitting the %TestResult% placeholder in the companion .md	Runtime results are not inserted into the test report

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Reference Examples

These existing files demonstrate the patterns described in this skill. Read them for concrete implementation guidance.

Complete CISA Check (Recommended Starting Point)

• Test file: tests/CISA/entra/Test-MtCisaWeakFactor.Tests.ps1
• Helper function: powershell/public/cisa/entra/Test-MtCisaWeakFactor.ps1
• Companion doc: powershell/public/cisa/entra/Test-MtCisaWeakFactor.md

Simple Maester Check

• Test file: tests/Maester/Entra/Test-AppManagementPolicies.Tests.ps1
• Helper function: powershell/public/maester/entra/Test-MtAppManagementPolicyEnabled.ps1
• Companion doc: powershell/public/maester/entra/Test-MtAppManagementPolicyEnabled.md

Website Documentation

• website/docs/tests/maester/MT.1001.md -- Conditional Access device compliance
• website/docs/tests/maester/MT.1024.md -- Entra recommendations
• website/docs/tests/maester/MT.1059.md -- Defender for Identity health issues

Parameterized Test (Dynamic Test Generation)

• tests/Maester/Defender/Test-MtMdiHealthIssues.Tests.ps1 -- Uses BeforeDiscovery and -ForEach

Custom Test Authoring Guide

• website/docs/writing-tests/index.mdx -- Getting started with custom tests
• website/docs/writing-tests/formatting-test-results.md -- Add-MtTestResultDetail patterns
• website/docs/writing-tests/advanced-concepts.md -- Invoke-MtGraphRequest, split-file pattern, error handling

Tagging Reference

• website/docs/tests/tags/readme.md -- Complete tag taxonomy with counts and usage recommendations

Contributing Guidelines

• .github/CONTRIBUTING.md -- Coding conventions, pre-PR checklist, PowerShell style requirements

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Troubleshooting

Symptom	Likely Cause	Resolution
Test shows as "Error" instead of "Skipped"	Add-MtTestResultDetail -SkippedBecause was called inside a try block	Move the call outside the try block
Test always fails with $null assertion error	Missing null check pattern around Should	Wrap assertion: if ($null -ne $result) { $result | Should ... }
Test runs but report shows no description	Companion .md file is missing or -Description was not provided	Create the companion .md or pass -Description to Add-MtTestResultDetail
%TestResult% appears literally in the report	The placeholder was not included in the -Result string when using -GraphObjects	Ensure the -Result string contains %TestResult%
403 Forbidden from Graph API	Missing permissions/scopes	Check Get-MtGraphScope for required scopes; add new scopes if needed
Test is never discovered by Pester	File name does not end with .Tests.ps1	Rename to include the .Tests.ps1 suffix
Helper function not found at runtime	Function not added to FunctionsToExport in powershell/Maester.psd1	Add the function name to the manifest
Test runs in local dev but is excluded in CI	Test is tagged LongRunning or Preview and CI does not use -IncludeLongRunning/-IncludePreview	Verify tags are intentional; adjust CI invocation if needed