From 9b853ad0af1bc9401677afa24a3ddeedb9ba7013 Mon Sep 17 00:00:00 2001
From: Jakub Majocha <1760221+majocha@users.noreply.github.com>
Date: Sat, 25 Jan 2025 10:29:33 +0100
Subject: [PATCH 1/2] fix flaky

---
 .../AttributeUsage/AttributeUsage.fs          | 32 ++++++++++---------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/tests/FSharp.Compiler.ComponentTests/Conformance/BasicGrammarElements/CustomAttributes/AttributeUsage/AttributeUsage.fs b/tests/FSharp.Compiler.ComponentTests/Conformance/BasicGrammarElements/CustomAttributes/AttributeUsage/AttributeUsage.fs
index 9b7cdc5a053..a28d6175642 100644
--- a/tests/FSharp.Compiler.ComponentTests/Conformance/BasicGrammarElements/CustomAttributes/AttributeUsage/AttributeUsage.fs
+++ b/tests/FSharp.Compiler.ComponentTests/Conformance/BasicGrammarElements/CustomAttributes/AttributeUsage/AttributeUsage.fs
@@ -34,21 +34,23 @@ module CustomAttributes_AttributeUsage =
         |> verifyCompileAndRun
         |> shouldSucceed
 
-    // SOURCE=AssemblyVersion03.fs                          # AssemblyVersion03.fs
-    [<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"AssemblyVersion03.fs"|])>]
-    let ``AssemblyVersion03_fs`` compilation =
-        compilation
-        |> withOptions ["--nowarn:52"]
-        |> verifyCompileAndRun
-        |> shouldSucceed
-
-    // SOURCE=AssemblyVersion04.fs							# AssemblyVersion04.fs
-    [<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"AssemblyVersion04.fs"|])>]
-    let ``AssemblyVersion04_fs`` compilation =
-        compilation
-        |> withOptions ["--nowarn:52"]
-        |> verifyCompileAndRun
-        |> shouldSucceed
+    [<Collection(nameof NotThreadSafeResourceCollection)>]
+    module TimeCritical =
+        // SOURCE=AssemblyVersion03.fs                          # AssemblyVersion03.fs
+        [<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"AssemblyVersion03.fs"|])>]
+        let ``AssemblyVersion03_fs`` compilation =
+            compilation
+            |> withOptions ["--nowarn:52"]
+            |> verifyCompileAndRun
+            |> shouldSucceed
+
+        // SOURCE=AssemblyVersion04.fs							# AssemblyVersion04.fs
+        [<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"AssemblyVersion04.fs"|])>]
+        let ``AssemblyVersion04_fs`` compilation =
+            compilation
+            |> withOptions ["--nowarn:52"]
+            |> verifyCompileAndRun
+            |> shouldSucceed
 
     // SOURCE=AttributeTargetsIsCtor01.fs				# AttributeTargetsIsCtor01.fs
     [<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"AttributeTargetsIsCtor01.fs"|])>]

From b9b04046505b943ce5eeaddf99c6d6788ec249d1 Mon Sep 17 00:00:00 2001
From: Jakub Majocha <1760221+majocha@users.noreply.github.com>
Date: Sat, 25 Jan 2025 10:29:41 +0100
Subject: [PATCH 2/2] meniton in devguide

---
 DEVGUIDE.md | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/DEVGUIDE.md b/DEVGUIDE.md
index 2ca137ba100..28b511fac04 100644
--- a/DEVGUIDE.md
+++ b/DEVGUIDE.md
@@ -243,6 +243,16 @@ or
 > Please note, that by default, **Release** version of IL baseline tests will be running in CI, so when updating baseline (.bsl) files, make sure to add `-c Release` flag to the build command.
 
 
+### Parallel execution of tests
+
+Tests utilizing xUnit framework by default run in parallel. If your tests depend on some shared state or are time-critical, you can add the module to predefined `NotThreadSafeResourceCollection` to prevent parallel execution.
+For example:
+```fsharp
+[<Collection(nameof NotThreadSafeResourceCollection)>]
+module TimeCritical =
+```
+
+
 ### Updating FCS surface area baselines
 
 ```bash