test: add a Hedgehog adapter for MSTest property tests

.github/copilot-instructions.md

@@ -29,6 +29,8 @@
 │   └── ValueCollections.fs – `Seq`, `List` and `Array` functions that return `voption` and struct tuples
 ├── tests/Cosmos.Tests/  – MSTest integration test project
 ├── tests/Cosmos.Tests.Infrastructure/ – shared test fixtures, emulator settings and assertion helpers
+├── tests/Hedgehog.MSTest/ – Hedgehog MSTest adapter for [<Property>] test methods (from hedgehogqa/fsharp-hedgehog)
+├── tests/Hedgehog.MSTest.Tests/ – the adapter's own test suite
 ├── build/               – FAKE build scripts
 └── docsSrc/             – FSharp.Formatting documentation source
 ```
@@ -40,6 +42,7 @@
 * [`FSharp.Control.Reactive`](https://github.com/fsprojects/FSharp.Reactive) – Rx extensions for F#
 * [`FsToolkit.ErrorHandling`](https://github.com/demystifyfp/FsToolkit.ErrorHandling) – `taskResult`, `Result`, `voption` CEs
 * [`Unquote`](https://github.com/SwensenSoftware/unquote) – test assertions
+* [`Hedgehog`](https://github.com/hedgehogqa/fsharp-hedgehog) – property-based testing through the `tests/Hedgehog.MSTest` adapter
 * [`MSTest`](https://github.com/microsoft/testfx) – test framework
 
 Use GitHub MCP tools for code search in these repositories when needed.
@@ -238,7 +241,9 @@ module MyTypeExtensions =
 * `COSMOS_EMULATOR_PARTITION_COUNT` is the number of partitions the emulator offers (default `25`, the Windows emulator's default `/PartitionCount`); the fixtures keep at most that many test containers at a time, one partition each.
 * `COSMOS_TEST_LEFTOVER_AGE_MINUTES` is how many minutes a `fsac-test-` database must stay unmodified before the leftover sweep of `[<AssemblyInitialize>]` and `[<AssemblyCleanup>]` deletes it (default `60`), so that the live databases of another test process on the same emulator are kept; `0` deletes every test database and is safe only while no other test process uses the emulator.
 * `COSMOS_REWRITE_BASELINES` set to `1` or `true` makes a test that compares SQL with its golden baseline (`Baseline.assertMatches`, files under `Baselines/<suite>/` of the test project) write what it produced into the baseline instead of comparing; the test then reports itself inconclusive, the rewritten files are reviewed in the diff, and CI refuses to rewrite.
-* Every test project under `tests/` references `tests/Cosmos.Tests.Infrastructure` through `tests/Directory.Build.props`; a new test project gets it without a `ProjectReference` of its own.
+* Every test project under `tests/` references `tests/Cosmos.Tests.Infrastructure` through `tests/Directory.Build.props`; a new test project gets it without a `ProjectReference` of its own. The Hedgehog MSTest adapter and its suite are the exception: they stay free of the Cosmos projects, and the suite references the adapter alone.
+* Property tests are methods of `[<TestClass>]` types marked `[<Property>]` (from `tests/Hedgehog.MSTest`), whose parameters Hedgehog generates; never call `Property.check` inside a `[<TestMethod>]`. A property is an instance method that returns `unit`, `Task` or `ValueTask` and fails by throwing: MSTest 4 rejects static methods and other return types, and one such method fails the discovery of the whole assembly, which `--list-tests` shows before a run. MSTest creates the test class and runs `[<TestInitialize>]` and `[<TestCleanup>]` for every generated case and every shrink step. A failed property reports a `[<Recheck("…")>]` to add next to its `Property` attribute, which then replays the counterexample. A parameter of type `DateOnly` or `TimeOnly`, or of a type that holds one, is generated like any other, and `[<DateOnly>]` and `[<TimeOnly>]` bound its value: Hedgehog 2.0.4 has no generator of the two types, so the adapter registers the ones that [hedgehogqa/fsharp-hedgehog#488](https://github.com/hedgehogqa/fsharp-hedgehog/pull/488) adds to Hedgehog, until a release has them. `Gen.auto` outside a property does not know the two types before that release.
+* `tests/Hedgehog.MSTest` and `tests/Hedgehog.MSTest.Tests` are ported from hedgehogqa/fsharp-hedgehog and proposed there too ([hedgehogqa/fsharp-hedgehog#487](https://github.com/hedgehogqa/fsharp-hedgehog/pull/487)). Their code follows the rules of this file, formatting with Fantomas and nullness checking included; the copy in the upstream pull request keeps upstream's style, so a change of behaviour goes into both. Copied files keep their Apache-2.0 header, which records every change made to them, and `THIRD-PARTY-NOTICES.md` lists them.
 * `CollectionAssert` cannot work with F# lists – use F# array syntax (`[| ... |]`) instead.
 * `StringAssert` has overloads with `StringComparison`.
 * Use `Assert.Contains` instead of `Assert.IsTrue (str.Contains ..., "message")`, and do not put the actual value into the message.

Directory.Packages.props

@@ -24,6 +24,7 @@
     <PackageVersion Include="Fake.DotNet.Paket" Version="6.1.5" />
     <PackageVersion Include="Fake.IO.FileSystem" Version="6.1.5" />
     <PackageVersion Include="Fake.Tools.Git" Version="6.1.5" />
+    <PackageVersion Include="Hedgehog" Version="2.0.4" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.5.1" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="10.0.401" />
     <PackageVersion Include="MSTest" Version="4.2.3" />

FSharp.Azure.Cosmos.slnf

@@ -4,7 +4,9 @@
     "projects": [
       "src\\Cosmos\\FSharp.Azure.Cosmos.fsproj",
       "tests\\Cosmos.Tests.Infrastructure\\FSharp.Azure.Cosmos.Tests.Infrastructure.fsproj",
-      "tests\\Cosmos.Tests\\FSharp.Azure.Cosmos.Tests.fsproj"
+      "tests\\Cosmos.Tests\\FSharp.Azure.Cosmos.Tests.fsproj",
+      "tests\\Hedgehog.MSTest\\Hedgehog.MSTest.fsproj",
+      "tests\\Hedgehog.MSTest.Tests\\Hedgehog.MSTest.Tests.fsproj"
     ]
   }
 }

FSharp.Azure.Cosmos.slnx

@@ -8,9 +8,12 @@
     <File Path="Directory.Packages.props" />
     <File Path="global.json" />
     <File Path="README.md" />
+    <File Path="THIRD-PARTY-NOTICES.md" />
   </Folder>
   <Project Path="build/build.fsproj" />
   <Project Path="src/Cosmos/FSharp.Azure.Cosmos.fsproj" />
   <Project Path="tests/Cosmos.Tests.Infrastructure/FSharp.Azure.Cosmos.Tests.Infrastructure.fsproj" />
   <Project Path="tests/Cosmos.Tests/FSharp.Azure.Cosmos.Tests.fsproj" />
+  <Project Path="tests/Hedgehog.MSTest/Hedgehog.MSTest.fsproj" />
+  <Project Path="tests/Hedgehog.MSTest.Tests/Hedgehog.MSTest.Tests.fsproj" />
 </Solution>

THIRD-PARTY-NOTICES.md

@@ -0,0 +1,35 @@
+# Third-party notices
+
+This repository contains code copied from the projects below. Each copied file names its origin and the changes made
+to it in a header comment. The rest of the repository is covered by [LICENSE](LICENSE).
+
+## fsharp-hedgehog
+
+* Source: <https://github.com/hedgehogqa/fsharp-hedgehog>, release commit
+  [`a46977278db9a60542e3df3fe0fcd74b90f38ee3`](https://github.com/hedgehogqa/fsharp-hedgehog/tree/a46977278db9a60542e3df3fe0fcd74b90f38ee3)
+  (Hedgehog 2.0.4; the repository has no tag for this release)
+* Copied into: `tests/Hedgehog.MSTest` (the Hedgehog MSTest adapter), from `src/Hedgehog.NUnit`: `Prelude.fs`,
+  `ReflectionHelpers.fs`, `AutoGenConfig.fs`, `IPropertyAttribute.fs`, `RecheckAttribute.fs`, `GenAttribute.fs`,
+  `GenAttribute.Prelude.fs`, `PropertyContext.fs`, `InternalLogic.fs`, `PropertiesAttribute.fs` and, adapted from
+  NUnit to MSTest, `PropertyAttribute.fs`
+* Ported into: `tests/Hedgehog.MSTest.Tests` (the adapter's suite), rewritten for MSTest, from
+  `tests/Hedgehog.Xunit.Tests.FSharp/PropertyTests.fs`, `tests/Hedgehog.NUnit.Tests.FSharp/PropertyTests.fs` and
+  `tests/Hedgehog.NUnit.Tests.FSharp/GenAttributePreludeTests.fs`: `Common.fs`, `PropertyTests.fs` and
+  `GenAttributePreludeTests.fs`
+* License: Apache License, Version 2.0
+
+```text
+Copyright (c) 2016 Jacob Stanley, Nikos Baxevanis
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+```

build/build.fs

@@ -353,16 +353,42 @@ let fsharpAnalyzers _ =
         dotnet.fsharpAnalyzer id args
     )
 
+/// <summary>
+/// Runs <c>dotnet test</c> without building for every test application, in the configuration of the executing targets
+/// and with the given arguments.
+/// </summary>
+/// <remarks>
+/// The arguments are written by hand, because
+/// <see cref="M:Fake.DotNet.DotNet.test(Microsoft.FSharp.Core.FSharpFunc{Fake.DotNet.DotNet.TestOptions,Fake.DotNet.DotNet.TestOptions},System.String)"/>
+/// cannot serve the Microsoft.Testing.Platform runner of the .NET 10 SDK: it adds MSBuild switches such as
+/// <c>/nodeReuse:False</c>, which that runner hands to the test application, where they are an invalid command line,
+/// and it offers the options of VSTest, which that runner does not have (https://github.com/fsprojects/FAKE/issues/2896).
+/// https://github.com/fsprojects/FAKE/pull/2903 adds a function for the runner; once FAKE releases it, it replaces
+/// this one.
+/// </remarks>
+let dotnetTestApplications ctx (args : string list) =
+    let dotnetConfiguration = configuration (ctx.Context.AllExecutingTargets) |> string
+
+    !!testsGlob
+    |> Seq.iter (fun testProject ->
+        [
+            "--project"
+            quoted testProject
+            "--no-build"
+            "--configuration"
+            dotnetConfiguration
+            yield! args
+        ]
+        |> String.concat " "
+        |> DotNet.exec id "test"
+        |> failOnBadExitAndPrint
+    )
+
 let dotnetTest ctx =
     // Create test results directory if it doesn't exist
     Directory.create testResultsDir
 
-    let dotnetConfiguration = configuration (ctx.Context.AllExecutingTargets) |> string
-
-    let args = [
-        "--no-build"
-        "--configuration"
-        dotnetConfiguration
+    dotnetTestApplications ctx [
         if enableCodeCoverage then
             "--coverage"
             "--coverage-output-format"
@@ -371,13 +397,12 @@ let dotnetTest ctx =
             quoted testResultsDir
     ]
 
-    !!testsGlob
-    |> Seq.iter (fun testProject ->
-        [ "--project"; quoted testProject; yield! args ]
-        |> String.concat " "
-        |> DotNet.exec id "test"
-        |> failOnBadExitAndPrint
-    )
+/// <summary>
+/// Lists the tests of every test application without running them. MSTest 4 fails the discovery of a whole assembly
+/// when one test method has a signature that it cannot run, such as a property method that returns a value, and the F#
+/// build gives no warning for it; listing reports that before the run, which needs the emulator, starts.
+/// </summary>
+let dotnetListTests ctx = dotnetTestApplications ctx [ "--list-tests" ]
 
 let generateCoverageReport _ =
 
@@ -392,8 +417,8 @@ let generateCoverageReport _ =
         sprintf "-targetdir:\"%s\"" coverageReportDir
         // Add source dir
         sprintf "-sourcedirs:\"%s\"" sourceDirs
-        // Ignore test assemblies and the helper libraries they share
-        sprintf "-assemblyfilters:\"%s\"" "-*.Tests;-*.Tests.Infrastructure"
+        // Ignore test assemblies, the helper libraries they share, the Hedgehog MSTest adapter and Hedgehog itself
+        sprintf "-assemblyfilters:\"%s\"" "-*.Tests;-*.Tests.Infrastructure;-Hedgehog;-Hedgehog.MSTest"
         // Generate HTML and Cobertura reports
         sprintf "-reporttypes:%s" "Html;Cobertura"
     ]
@@ -639,6 +664,7 @@ let initTargets (ctx : Context.FakeExecutionContext) =
     Target.createFinal "DeleteChangelogBackupFile" deleteChangelogBackupFile // Do NOT put this in the dependency chain
     Target.create "DotnetBuild" dotnetBuild
     Target.create "FSharpAnalyzers" fsharpAnalyzers
+    Target.create "DotnetListTests" dotnetListTests
     Target.create "DotnetTest" dotnetTest
     Target.create "GenerateCoverageReport" generateCoverageReport
     Target.create "ShowCoverageReport" showCoverageReport
@@ -700,6 +726,7 @@ let initTargets (ctx : Context.FakeExecutionContext) =
 
     "DotnetRestore" =?> ("CheckFormatCode", isCI.Value)
     ==> "DotnetBuild"
+    ==> "DotnetListTests"
     ==> "DotnetTest"
     ==> "DotnetPack"
     ==> "PublishToNuGet"
@@ -710,6 +737,7 @@ let initTargets (ctx : Context.FakeExecutionContext) =
     =?> ("CheckFormatCode", isCI.Value)
     =?> ("GenerateAssemblyInfo", isPublishToGitHub)
     ==> "DotnetBuild"
+    ==> "DotnetListTests"
     ==> "DotnetTest"
     ==> "DotnetPack"
     ==>! "PublishToGitHub"

tests/Directory.Build.props

@@ -6,10 +6,14 @@
     </PropertyGroup>
 
     <!--
-      Every test project shares the test infrastructure (fixtures, emulator budget, assertion helpers); the
-      infrastructure project itself is excluded, because a project cannot reference itself.
+      Every test project shares the test infrastructure (fixtures, emulator budget, assertion helpers). Excluded are
+      the infrastructure project itself, because a project cannot reference itself, and the Hedgehog MSTest adapter
+      and its suite, which stay free of this repository's projects: the adapter is also proposed to
+      hedgehogqa/fsharp-hedgehog, and its package replaces both once upstream publishes it.
     -->
-    <ItemGroup Condition="'$(MSBuildProjectName)' != 'FSharp.Azure.Cosmos.Tests.Infrastructure'">
+    <ItemGroup Condition="'$(MSBuildProjectName)' != 'FSharp.Azure.Cosmos.Tests.Infrastructure'
+                          AND '$(MSBuildProjectName)' != 'Hedgehog.MSTest'
+                          AND '$(MSBuildProjectName)' != 'Hedgehog.MSTest.Tests'">
         <ProjectReference Include="$(MSBuildThisFileDirectory)Cosmos.Tests.Infrastructure/FSharp.Azure.Cosmos.Tests.Infrastructure.fsproj" />
     </ItemGroup>
 </Project>

tests/Hedgehog.MSTest.Tests/Common.fs

@@ -0,0 +1,57 @@
+// The configurations and generator attributes that the tests share, from the suites of hedgehogqa/fsharp-hedgehog at
+// the Hedgehog 2.0.4 release commit a46977278db9a60542e3df3fe0fcd74b90f38ee3 (tests/Hedgehog.Xunit.Tests.FSharp and
+// tests/Hedgehog.NUnit.Tests.FSharp, PropertyTests.fs).
+// Copyright (c) 2016 Jacob Stanley, Nikos Baxevanis. Licensed under the Apache License, Version 2.0
+// (http://www.apache.org/licenses/LICENSE-2.0); see THIRD-PARTY-NOTICES.md at the root of this repository.
+// Changes: the generator attributes carry the Attribute suffix; upstream declares PropertyInt13Attribute and
+// PropertiesInt13Attribute next to their tests.
+// The file is formatted with Fantomas, under the settings of this repository.
+
+namespace Hedgehog.MSTest.Tests
+
+open System
+open Hedgehog
+open Hedgehog.FSharp
+open Hedgehog.MSTest
+
+/// An AutoGenConfig type whose every int is 13.
+type Int13 =
+    static member __ =
+        AutoGenConfig.defaults
+        |> AutoGenConfig.addGenerator (Gen.constant 13)
+
+/// An AutoGenConfig type whose every int is 2718.
+type Int2718 =
+    static member __ =
+        AutoGenConfig.empty
+        |> AutoGenConfig.addGenerator (Gen.constant 2718)
+
+/// An AutoGenConfig type whose every int is 13 and every string is "A".
+type Int13A =
+    static member __ =
+        AutoGenConfig.empty
+        |> AutoGenConfig.addGenerator (Gen.constant 13)
+        |> AutoGenConfig.addGenerator (Gen.constant "A")
+
+/// Sets an int parameter to 5.
+type Int5Attribute () =
+    inherit GenAttribute<int> ()
+    override _.Generator = Gen.constant 5
+
+/// Sets an int parameter to 6.
+type Int6Attribute () =
+    inherit GenAttribute<int> ()
+    override _.Generator = Gen.constant 6
+
+/// Generates an int parameter from a constant range.
+type IntConstantRangeAttribute (min : int, max : int) =
+    inherit GenAttribute<int> ()
+    override _.Generator = Range.constant min max |> Gen.int32
+
+/// A PropertyAttribute subclass that names Int13 itself.
+type PropertyInt13Attribute () =
+    inherit PropertyAttribute (typeof<Int13>)
+
+/// A PropertiesAttribute subclass that names Int13 itself.
+type PropertiesInt13Attribute () =
+    inherit PropertiesAttribute (typeof<Int13>)