From d8b12d131c05918d9a3e94b84561c76fad1ef4d4 Mon Sep 17 00:00:00 2001
From: Kazuki Nishikawa <kz.nishikawa@gmail.com>
Date: Wed, 24 Dec 2025 18:03:03 +0900
Subject: [PATCH 1/4] Add test cases that causes an error in ERB formatting

---
 spec/lib/rufo/erb_formatter_spec.rb | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/spec/lib/rufo/erb_formatter_spec.rb b/spec/lib/rufo/erb_formatter_spec.rb
index 9ad8816c..fca626c6 100644
--- a/spec/lib/rufo/erb_formatter_spec.rb
+++ b/spec/lib/rufo/erb_formatter_spec.rb
@@ -90,6 +90,16 @@
       expect(result).to eql("<%= yield %>")
     end
 
+    it "formats standalone 'yield' with arguments" do
+      result = subject.format("<%=yield x,y%>")
+      expect(result).to eql("<%= yield x, y %>")
+    end
+
+    it "formats standalone 'yield' with arguments and parens" do
+      result = subject.format("<%=yield(x,y)%>")
+      expect(result).to eql("<%= yield(x, y) %>")
+    end
+
     it "handles native erb comments" do
       result = subject.format("<%# locals: (item:, variant:) %>")
       expect(result).to eql("<%# locals: (item:, variant:) %>")
@@ -99,5 +109,20 @@
       result = subject.format("<% # TODO: fix this later %>")
       expect(result).to eql("<% # TODO: fix this later %>")
     end
+
+    it 'handles case/when expression' do
+      result = subject.format(<<~ERB)
+        <% case a+b %>
+        <% when c %>
+        <%= d+e %>
+        <% end %>
+      ERB
+      expect(result).to eql(<<~ERB)
+        <% case a + b %>
+        <% when c %>
+        <%= d + e %>
+        <% end %>
+      ERB
+    end
   end
 end

From a78ab231b30698a5bb50d5b9c3145388f1de86da Mon Sep 17 00:00:00 2001
From: Kazuki Nishikawa <kz.nishikawa@gmail.com>
Date: Wed, 24 Dec 2025 18:07:28 +0900
Subject: [PATCH 2/4] format

---
 spec/lib/rufo/erb_formatter_spec.rb | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/spec/lib/rufo/erb_formatter_spec.rb b/spec/lib/rufo/erb_formatter_spec.rb
index fca626c6..8db16d52 100644
--- a/spec/lib/rufo/erb_formatter_spec.rb
+++ b/spec/lib/rufo/erb_formatter_spec.rb
@@ -110,7 +110,7 @@
       expect(result).to eql("<% # TODO: fix this later %>")
     end
 
-    it 'handles case/when expression' do
+    it "handles case/when expression" do
       result = subject.format(<<~ERB)
         <% case a+b %>
         <% when c %>
@@ -118,11 +118,11 @@
         <% end %>
       ERB
       expect(result).to eql(<<~ERB)
-        <% case a + b %>
-        <% when c %>
-        <%= d + e %>
-        <% end %>
-      ERB
+                          <% case a + b %>
+                          <% when c %>
+                          <%= d + e %>
+                          <% end %>
+                        ERB
     end
   end
 end

From c582ed7971f8bcd5bff4476c7fe2acdd146a411d Mon Sep 17 00:00:00 2001
From: Kazuki Nishikawa <kz.nishikawa@gmail.com>
Date: Thu, 28 May 2026 21:10:41 +0900
Subject: [PATCH 3/4] Fix ERB formatting for yield with args and case/when
 blocks

Two fixes for code that previously raised SyntaxError in ErbFormatter:

- yield with multiple args / parens: Ripper.sexp returns nil for these
  at top level, so process_code fell through to determine_code_wrappers
  and then to raise_syntax_error!. raise_syntax_error! calls format_code
  expecting it to raise, but Rufo::Formatter handles yield via
  sexp_unparsable_code and instead returned a formatted string, which
  was then mis-assigned as `prefix` and produced corrupt input. Use
  Rufo::Parser.sexp_unparsable_code as the Ripper.sexp fallback so
  these forms skip the wrapper logic entirely.

- `case EXPR` alone (split across ERB tags): none of the existing
  wrappers make a bare case header parse, since case requires a when
  clause. Add a `\nwhen nil\nend` suffix wrapper so the header tag is
  parseable in isolation.
---
 lib/rufo/erb_formatter.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/rufo/erb_formatter.rb b/lib/rufo/erb_formatter.rb
index 2509c619..fb9d9d53 100644
--- a/lib/rufo/erb_formatter.rb
+++ b/lib/rufo/erb_formatter.rb
@@ -90,7 +90,7 @@ def process_erb
   end
 
   def process_code(code_str)
-    sexps = Ripper.sexp(code_str)
+    sexps = Ripper.sexp(code_str) || Rufo::Parser.sexp_unparsable_code(code_str)
     if sexps.nil?
       prefix, suffix = determine_code_wrappers(code_str)
     end
@@ -157,6 +157,7 @@ def determine_code_wrappers(code_str)
     return "begin\n", "\nend" if Ripper.sexp("begin\n#{code_str}\nend")
     return "if a\n", "\nend" if Ripper.sexp("if a\n#{code_str}\nend")
     return "case a\n", "\nend" if Ripper.sexp("case a\n#{code_str}\nend")
+    return nil, "\nwhen nil\nend" if Ripper.sexp("#{code_str}\nwhen nil\nend")
     raise_syntax_error!(code_str)
   end
 

From b10fa7a0af0216b6b6488055c73984ae9c042c5f Mon Sep 17 00:00:00 2001
From: Kazuki Nishikawa <kz.nishikawa@gmail.com>
Date: Thu, 28 May 2026 21:12:28 +0900
Subject: [PATCH 4/4] run rufo

---
 spec/lib/rufo/erb_formatter_spec.rb | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/spec/lib/rufo/erb_formatter_spec.rb b/spec/lib/rufo/erb_formatter_spec.rb
index 9951ec88..c7fbfa21 100644
--- a/spec/lib/rufo/erb_formatter_spec.rb
+++ b/spec/lib/rufo/erb_formatter_spec.rb
@@ -138,11 +138,11 @@
         <% end %>
       ERB
       expect(result).to eql(<<~ERB)
-        <% case a + b %>
-        <% when c %>
-        <%= d + e %>
-        <% end %>
-      ERB
+                          <% case a + b %>
+                          <% when c %>
+                          <%= d + e %>
+                          <% end %>
+                        ERB
     end
   end
 end