From ae265115da3fd2dfcbc83927a0c5a3f779624c44 Mon Sep 17 00:00:00 2001
From: Brandon Weaver <keystonelemur@gmail.com>
Date: Tue, 5 Oct 2021 21:50:54 -0700
Subject: [PATCH] Adds spec for #17260 and #17231

Adds specs for one-line pattern matching syntax in Ruby 3.0+, including
both Righthand Assignment (`=>`) and one-line match (`in`).
---
 language/pattern_matching_spec.rb | 59 +++++++++++++++++++++++++++----
 1 file changed, 53 insertions(+), 6 deletions(-)

diff --git a/language/pattern_matching_spec.rb b/language/pattern_matching_spec.rb
index c6a3008458..5470696035 100644
--- a/language/pattern_matching_spec.rb
+++ b/language/pattern_matching_spec.rb
@@ -10,12 +10,49 @@
     end
 
     ruby_version_is "3.0" do
-      it "can be standalone assoc operator that deconstructs value" do
-        suppress_warning do
-          eval(<<-RUBY).should == [0, 1]
-            [0, 1] => [a, b]
-            [a, b]
-          RUBY
+      describe "Rightward assignment (`=>`)" do
+        it "can be standalone assoc operator that deconstructs value" do
+          suppress_warning do
+            eval(<<~RUBY).should == [0, 1]
+              [0, 1] => [a, b]
+              [a, b]
+            RUBY
+          end
+        end
+
+        it "can work with keywords" do
+          suppress_warning do
+            eval(<<~RUBY).should == [0, 1]
+              { a: 0, b: 1 } => { a:, b: }
+              [a, b]
+            RUBY
+          end
+        end
+      end
+
+      describe "One-line pattern matching" do
+        it "can be used to check if a pattern matches for Array-like entities" do
+          suppress_warning do
+            eval(<<~RUBY).should == true
+              [0, 1] in [a, b]
+            RUBY
+
+            eval(<<~RUBY).should == false
+              [0, 1] in [a, b, c]
+            RUBY
+          end
+        end
+
+        it "can be used to check if a pattern matches for Hash-like entities" do
+          suppress_warning do
+            eval(<<~RUBY).should == true
+              { a: 0, b: 1 } in { a:, b: }
+            RUBY
+
+            eval(<<~RUBY).should == false
+              { a: 0, b: 1 } in { a:, b:, c: }
+            RUBY
+          end
         end
       end
     end
@@ -1136,6 +1173,16 @@ def ===(obj)
       end
     end
 
+    ruby_version_is ""..."2.7" do
+      it "raises NoMatchingPatternError if no pattern matches for one-line patterns" do
+        -> {
+          eval <<~RUBY
+            0 in 1
+          RUBY
+        }.should raise_error(NoMatchingPatternError, /\[0, 1\]/)
+      end
+    end
+
     ruby_version_is "3.1" do
       it "can omit parentheses in one line pattern matching" do
         eval(<<~RUBY).should == [1, 2]