Generate release notes in pipeline

Author: nohwnd

scripts/write-release-notes.ps1

@@ -0,0 +1,119 @@
+[CmdletBinding()]
+param
+( 
+   [string] $Path = ".",
+   # if this is a pre-release or stable version
+   [switch] $Stable,
+   # externally provide the version number we will use
+   [string] $PackageVersion,
+   # in CI we don't know the end tag, so we diff till the current commit
+   [switch] $EndWithLatestCommit
+)
+
+if ($EndWithLatestCommit -and [string]::IsNullOrWhiteSpace($PackageVersion)) { 
+    throw "EndWithLatestCommit was enabled, provide PackageVersion in this format 16.8.0-preview-20200924-01, or this format 16.8.0."
+}
+
+$repoUrl = $(if ((git -C $Path remote -v) -match "upstream") {
+        git -C $Path remote get-url --push upstream
+    }
+    else {  
+        git -C $Path remote get-url --push origin
+    })-replace "\.git$" 
+
+# list all tags on this branch ordered by creator date to get the latest, stable or pre-release tag. 
+# For stable release we choose only tags without any dash, for pre-release we choose all tags.
+$tags = git -C $Path tag -l --sort=creatordate | Where-Object { $_ -match "v\d+\.\d+\.\d+.*" -and (-not $Stable -or $_ -notlike '*-*') }
+
+if ($EndWithLatestCommit) { 
+    # in CI we don't have the tag yet, so we show changes between the most recent tag, and this commit
+    # we figure out the tag from the package version that is set by vsts-prebuild
+    $start = $tags | Select-Object -Last 1
+    $end = git -C $Path rev-parse HEAD
+    $tag = "v$PackageVersion"
+}
+else { 
+    # normally we show changes between the latest two tags
+    $start, $end = $tags | Select-Object -Last 2
+    $tag = $end
+}
+
+# # override the tags to use if you need
+# $start = "v16.8.0-preview-20200812-03"
+# $end = $tag = "v16.8.0-preview-20200921-01"
+
+
+Write-Host "Generating release notes for $start..$end$(if ($EndWithLatestCommit) { " (expected tag: $tag)" })"
+
+$sourceBranch = $branch = git -C $Path rev-parse --abbrev-ref HEAD
+if ($sourceBranch -eq "HEAD") { 
+    # when CI checks out just the single commit, https://docs.microsoft.com/en-us/azure/devops/pipelines/build/variables?view=azure-devops&tabs=yaml
+    $sourceBranch = $env:BUILD_SOURCEBRANCH -replace "^refs/heads/"  
+}
+
+if ([string]::IsNullOrWhiteSpace($branch)) { 
+    throw "Branch is null or empty!"
+}
+
+if ([string]::IsNullOrWhiteSpace($sourceBranch)) { 
+    throw "SourceBranch is null or empty!"
+}
+
+Write-Host "Branch is $branch"
+Write-Host "SourceBranch is $sourceBranch"
+$branchesWithStartTag = git -C $Path branch --contains tags/$start
+
+if (-not $branchesWithStartTag -or $branchesWithStartTag -notmatch $branch) { 
+    Write-Host "This branch $branch$(if($branch -ne $sourceBranch){" ($sourceBranch)"}), does not contain the starting tag $start. Skipping generating release notes."
+    if ($branchesWithStartTag) {
+        Write-Host "The tag is present on branches:`n$($branchesWithStartTag)."
+    }
+    return 
+}
+else { 
+    Write-Host "Branch $branch$(if($branch -ne $sourceBranch){" ($sourceBranch)"}) has tag $start, getting log since that."
+}
+
+$prUrl = "$repoUrl/pull/"
+$v = $tag -replace '^v'
+$b = if ($Stable) { $v } else { $tag -replace '.*?(\d+-\d+)$', '$1' }
+# using .. because I want to know the changes that are on this branch, but don't care about the changes that I don't have https://stackoverflow.com/a/24186641/3065397
+$log = (git -C $Path log "$start..$end" --oneline --pretty="format:%s" --first-parent  --no-merges)
+$issues = $log | ForEach-Object {
+    if ($_ -match '^(?<message>.+)\s\(#(?<pr>\d+)\)?$') {
+        $message = "* $($matches.message)"
+        if ($matches.pr) {
+            $pr = $matches.pr
+            $message += " [#$pr]($prUrl$pr)"
+        }
+
+        $message
+    }
+    else
+    {
+        "* $_"
+    }
+}
+
+$output = @"
+
+See the release notes [here](https://github.com/microsoft/vstest-docs/blob/master/docs/releases.md#$($v -replace '\.')).
+
+-------------------------------
+
+## $v
+
+### Issue Fixed
+$($issues -join "`n")
+
+See full log [here]($repoUrl/compare/$start...$tag)
+
+### Drops
+
+* TestPlatform vsix: [$v](https://vsdrop.corp.microsoft.com/file/v1/Products/DevDiv/microsoft/vstest/$sourceBranch/$b;/TestPlatform.vsix)
+* Microsoft.TestPlatform.ObjectModel : [$v](https://www.nuget.org/packages/Microsoft.TestPlatform.ObjectModel/$v)
+"@
+
+
+$output
+$output | clip