From 1bf1b64cbbc5e70fe46de4aa2e18ec3885003825 Mon Sep 17 00:00:00 2001
From: Julien Couvreur <jcouv@users.noreply.github.com>
Date: Tue, 2 Apr 2019 23:03:40 +0200
Subject: [PATCH] Format `{}` property pattern (#34619)

---
 .../AutomaticBraceCompletionTests.cs          |   6 +-
 .../Rules/TokenBasedFormattingRule.cs         |   8 ++
 .../CSharpTest/Formatting/FormattingTests.cs  | 101 ++++++++++++++++--
 3 files changed, 104 insertions(+), 11 deletions(-)

diff --git a/src/EditorFeatures/CSharpTest/AutomaticCompletion/AutomaticBraceCompletionTests.cs b/src/EditorFeatures/CSharpTest/AutomaticCompletion/AutomaticBraceCompletionTests.cs
index 2885a9dd05e82..638e3f3c6ca1d 100644
--- a/src/EditorFeatures/CSharpTest/AutomaticCompletion/AutomaticBraceCompletionTests.cs
+++ b/src/EditorFeatures/CSharpTest/AutomaticCompletion/AutomaticBraceCompletionTests.cs
@@ -388,7 +388,7 @@ class C
 {
     void M()
     {
-        _ = this is { }
+        _ = this is {}
     }
 }";
 
@@ -431,7 +431,7 @@ class C
 {
     void M()
     {
-        _ = this is { }
+        _ = this is {}
         M();
     }
 }";
@@ -476,7 +476,7 @@ class C
 {
     void M()
     {
-        _ = this is (1, 2) { }
+        _ = this is (1, 2) {}
         M();
     }
 }";
diff --git a/src/Workspaces/CSharp/Portable/Formatting/Rules/TokenBasedFormattingRule.cs b/src/Workspaces/CSharp/Portable/Formatting/Rules/TokenBasedFormattingRule.cs
index 9cbe3b6fbc8b7..1c9fb66e5cbf9 100644
--- a/src/Workspaces/CSharp/Portable/Formatting/Rules/TokenBasedFormattingRule.cs
+++ b/src/Workspaces/CSharp/Portable/Formatting/Rules/TokenBasedFormattingRule.cs
@@ -257,6 +257,14 @@ public override AdjustSpacesOperation GetAdjustSpacesOperation(SyntaxToken previ
                 return CreateAdjustSpacesOperation(0, AdjustSpacesOption.ForceSpacesIfOnSingleLine);
             }
 
+            // empty {} in pattern
+            if (previousToken.Kind() == SyntaxKind.OpenBraceToken &&
+                currentToken.Kind() == SyntaxKind.CloseBraceToken &&
+                currentToken.Parent.IsKind(SyntaxKindEx.PropertyPatternClause))
+            {
+                return CreateAdjustSpacesOperation(0, AdjustSpacesOption.ForceSpacesIfOnSingleLine);
+            }
+
             // attribute case
             // , [
             if (previousToken.Kind() == SyntaxKind.CommaToken && currentToken.Kind() == SyntaxKind.OpenBracketToken && currentToken.Parent is AttributeListSyntax)
diff --git a/src/Workspaces/CSharpTest/Formatting/FormattingTests.cs b/src/Workspaces/CSharpTest/Formatting/FormattingTests.cs
index 5dff817509dc0..a8416263d3aea 100644
--- a/src/Workspaces/CSharpTest/Formatting/FormattingTests.cs
+++ b/src/Workspaces/CSharpTest/Formatting/FormattingTests.cs
@@ -5142,7 +5142,7 @@ void M() {
 {
     void M()
     {
-        _ = this is C(1, 2) { };
+        _ = this is C(1, 2) {};
     }
 }";
             // no space separates the type and the positional pattern
@@ -5165,7 +5165,7 @@ void M() {
 {
     void M()
     {
-        _ = this is C (1, 2) { };
+        _ = this is C (1, 2) {};
     }
 }";
             await AssertFormatAsync(expectedCode, code, changedOptionSet: changingOptions);
@@ -5188,8 +5188,8 @@ void M() {
 {
     void M()
     {
-        _ = this is C( 1, 2 ) { };
-        _ = this is C() { };
+        _ = this is C( 1, 2 ) {};
+        _ = this is C() {};
     }
 }";
             await AssertFormatAsync(expectedCode, code, changedOptionSet: changingOptions);
@@ -5212,8 +5212,8 @@ void M() {
 {
     void M()
     {
-        _ = this is C(1, 2) { };
-        _ = this is C( ) { };
+        _ = this is C(1, 2) {};
+        _ = this is C( ) {};
     }
 }";
             await AssertFormatAsync(expectedCode, code, changedOptionSet: changingOptions);
@@ -5290,7 +5290,7 @@ void M() {
 {
     void M()
     {
-        _ = this is { }
+        _ = this is {}
         M();
     }
 }";
@@ -5313,7 +5313,7 @@ void M() {
 {
     void M()
     {
-        _ = this is (1, 2) { }
+        _ = this is (1, 2) {}
         M();
     }
 }";
@@ -9069,6 +9069,91 @@ public void Foo()
 }");
         }
 
+        [Fact, Trait(Traits.Feature, Traits.Features.Formatting)]
+        public async Task EmptyIsPropertyPattern()
+        {
+            var code = @"
+class C
+{
+    void M()
+    {
+        _ = x is { }
+    }
+}
+";
+            var expected = @"
+class C
+{
+    void M()
+    {
+        _ = x is {}
+    }
+}
+";
+
+            await AssertFormatAsync(expected, code);
+        }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.Formatting)]
+        public async Task EmptySwitchCasePropertyPattern()
+        {
+            var code = @"
+class C
+{
+    void M()
+    {
+        switch (x)
+        {
+            case { }
+        }
+    }
+}
+";
+            var expected = @"
+class C
+{
+    void M()
+    {
+        switch (x)
+        {
+            case {}
+        }
+    }
+}
+";
+
+            await AssertFormatAsync(expected, code);
+        }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.Formatting)]
+        public async Task EmptySwitchExpressionCasePropertyPattern()
+        {
+            var code = @"
+class C
+{
+    void M()
+    {
+        _ = x switch
+        {
+            { } =>
+    }
+}
+";
+            var expected = @"
+class C
+{
+    void M()
+    {
+        _ = x switch
+        {
+            {} =>
+    }
+}
+";
+
+            await AssertFormatAsync(expected, code);
+        }
+
         [Theory, Trait(Traits.Feature, Traits.Features.Formatting)]
         [WorkItem(31571, "https://github.com/dotnet/roslyn/issues/31571")]
         [WorkItem(33910, "https://github.com/dotnet/roslyn/issues/33910")]