From 748e6582302699ede4098bcb965c411ae5f20908 Mon Sep 17 00:00:00 2001
From: nojaf <florian.verdonck@outlook.com>
Date: Sat, 11 Jun 2022 17:26:06 +0200
Subject: [PATCH] Print leading newlines when formatting a selection.

---
 src/Fantomas.Core.Tests/ContextTests.fs                 | 2 ++
 src/Fantomas.Core.Tests/FormattingSelectionOnlyTests.fs | 4 ++--
 src/Fantomas.Core/CodeFormatterImpl.fs                  | 2 +-
 src/Fantomas.Core/Context.fs                            | 9 +++++++--
 4 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/Fantomas.Core.Tests/ContextTests.fs b/src/Fantomas.Core.Tests/ContextTests.fs
index fc0f369d98..a927dd3d48 100644
--- a/src/Fantomas.Core.Tests/ContextTests.fs
+++ b/src/Fantomas.Core.Tests/ContextTests.fs
@@ -7,6 +7,8 @@ open Fantomas.Core.Tests.TestHelper
 open Fantomas.Core.FormatConfig
 open Fantomas.Core
 
+let private dump = dump false
+
 [<Test>]
 let ``sepSpace should not add an additional space if the line ends with a space`` () =
     let expr = !- "let a = " +> sepSpace
diff --git a/src/Fantomas.Core.Tests/FormattingSelectionOnlyTests.fs b/src/Fantomas.Core.Tests/FormattingSelectionOnlyTests.fs
index 2fc25ce81f..f175540ad4 100644
--- a/src/Fantomas.Core.Tests/FormattingSelectionOnlyTests.fs
+++ b/src/Fantomas.Core.Tests/FormattingSelectionOnlyTests.fs
@@ -74,6 +74,7 @@ let x =
     |> should
         equal
         "
+
 try
     something ()
 with ex ->
@@ -125,8 +126,7 @@ let a =  9
         equal
         """
 
-let a = 9
-"""
+let a = 9"""
 
 // 10	25	10	82
 //[<Test>]
diff --git a/src/Fantomas.Core/CodeFormatterImpl.fs b/src/Fantomas.Core/CodeFormatterImpl.fs
index 8e79a31021..16ac976823 100644
--- a/src/Fantomas.Core/CodeFormatterImpl.fs
+++ b/src/Fantomas.Core/CodeFormatterImpl.fs
@@ -65,7 +65,7 @@ let formatWith
 
         context
         |> genParsedInput ASTContext.Default ast
-        |> Context.dump
+        |> Context.dump (Option.isSome selection)
 
     formattedSourceCode
 
diff --git a/src/Fantomas.Core/Context.fs b/src/Fantomas.Core/Context.fs
index 0ec30fef50..0ffa009647 100644
--- a/src/Fantomas.Core/Context.fs
+++ b/src/Fantomas.Core/Context.fs
@@ -295,7 +295,7 @@ let finalizeWriterModel (ctx: Context) =
     else
         ctx
 
-let dump (ctx: Context) =
+let dump (isSelection: bool) (ctx: Context) =
     let ctx = finalizeWriterModel ctx
 
     match ctx.WriterModel.Lines with
@@ -304,7 +304,12 @@ let dump (ctx: Context) =
         // Always trim the last line
         h.TrimEnd() :: tail
     |> List.rev
-    |> List.skipWhile ((=) "")
+    |> fun lines ->
+        // Don't skip leading newlines when formatting a selection.
+        if isSelection then
+            lines
+        else
+            List.skipWhile ((=) "") lines
     |> String.concat ctx.Config.EndOfLine.NewLineString
 
 let dumpAndContinue (ctx: Context) =