1 files changed, 161 insertions, 12 deletions
diff --git a/spec/ruby/language/pattern_matching_spec.rb b/spec/ruby/language/pattern_matching_spec.rb
index c6a3008458..e4abae9412 100644
--- a/spec/ruby/language/pattern_matching_spec.rb
+++ b/spec/ruby/language/pattern_matching_spec.rb
@@ -18,6 +18,63 @@ ruby_version_is "2.7" do
           RUBY
         end
       end
+
+      describe "find pattern" do
+        it "captures preceding elements to the pattern" do
+          eval(<<~RUBY).should == [0, 1]
+            case [0, 1, 2, 3]
+            in [*pre, 2, 3]
+              pre
+            else
+              false
+            end
+          RUBY
+        end
+
+        it "captures following elements to the pattern" do
+          eval(<<~RUBY).should == [2, 3]
+            case [0, 1, 2, 3]
+            in [0, 1, *post]
+              post
+            else
+              false
+            end
+          RUBY
+        end
+
+        it "captures both preceding and following elements to the pattern" do
+          eval(<<~RUBY).should == [[0, 1], [3, 4]]
+            case [0, 1, 2, 3, 4]
+            in [*pre, 2, *post]
+              [pre, post]
+            else
+              false
+            end
+          RUBY
+        end
+
+        it "can capture the entirety of the pattern" do
+          eval(<<~RUBY).should == [0, 1, 2, 3, 4]
+            case [0, 1, 2, 3, 4]
+            in [*everything]
+              everything
+            else
+              false
+            end
+          RUBY
+        end
+
+        it "will match an empty Array-like structure" do
+          eval(<<~RUBY).should == []
+            case []
+            in [*everything]
+              everything
+            else
+              false
+            end
+          RUBY
+        end
+      end
     end
 
     it "extends case expression with case/in construction" do
@@ -41,25 +98,49 @@ ruby_version_is "2.7" do
     end
 
     describe "warning" do
-      ruby_version_is ""..."3.1" do
+      before :each do
+        @experimental, Warning[:experimental] = Warning[:experimental], true
+      end
+
+      after :each do
+        Warning[:experimental] = @experimental
+      end
+
+      context 'when regular form' do
         before :each do
-          ruby_version_is ""..."3.0" do
-            @src = 'case [0, 1]; in [a, b]; end'
-          end
+          @src = 'case [0, 1]; in [a, b]; end'
+        end
 
-          ruby_version_is "3.0" do
-            @src = '[0, 1] => [a, b]'
+        ruby_version_is ""..."3.0" do
+          it "warns about pattern matching is experimental feature" do
+            -> { eval @src }.should complain(/pattern matching is experimental, and the behavior may change in future versions of Ruby!/i)
           end
-
-          @experimental, Warning[:experimental] = Warning[:experimental], true
         end
 
-        after :each do
-          Warning[:experimental] = @experimental
+        ruby_version_is "3.0" do
+          it "does not warn about pattern matching is experimental feature" do
+            -> { eval @src }.should_not complain
+          end
         end
+      end
+
+      context 'when one-line form' do
+        ruby_version_is '3.0' do
+          before :each do
+            @src = '[0, 1] => [a, b]'
+          end
+
+          ruby_version_is ""..."3.1" do
+            it "warns about pattern matching is experimental feature" do
+              -> { eval @src }.should complain(/pattern matching is experimental, and the behavior may change in future versions of Ruby!/i)
+            end
+          end
 
-        it "warns about pattern matching is experimental feature" do
-          -> { eval @src }.should complain(/pattern matching is experimental, and the behavior may change in future versions of Ruby!/i)
+          ruby_version_is "3.1" do
+            it "does not warn about pattern matching is experimental feature" do
+              -> { eval @src }.should_not complain
+            end
+          end
         end
       end
     end
@@ -444,6 +525,28 @@ ruby_version_is "2.7" do
           end
         RUBY
       end
+
+      it "can be used as a nested pattern" do
+        eval(<<~RUBY).should == true
+          case [[1], ["2"]]
+            in [[0] | nil, _]
+              false
+            in [[1], [1]]
+              false
+            in [[1], [2 | "2"]]
+              true
+          end
+        RUBY
+
+        eval(<<~RUBY).should == true
+          case [1, 2]
+            in [0, _] | {a: 0}
+              false
+            in {a: 1, b: 2} | [1, 2]
+              true
+          end
+        RUBY
+      end
     end
 
     describe "AS pattern" do
@@ -705,6 +808,28 @@ ruby_version_is "2.7" do
           end
         RUBY
       end
+
+      it "can be used as a nested pattern" do
+        eval(<<~RUBY).should == true
+          case [[1], ["2"]]
+            in [[0] | nil, _]
+              false
+            in [[1], [1]]
+              false
+            in [[1], [2 | "2"]]
+              true
+          end
+        RUBY
+
+        eval(<<~RUBY).should == true
+          case [1, 2]
+            in [0, _] | {a: 0}
+              false
+            in {a: 1, b: 2} | [1, 2]
+              true
+          end
+        RUBY
+      end
     end
 
     describe "Hash pattern" do
@@ -1060,6 +1185,30 @@ ruby_version_is "2.7" do
           end
         RUBY
       end
+
+      it "can be used as a nested pattern" do
+        eval(<<~RUBY).should == true
+          case {a: {a: 1, b: 1}, b: {a: 1, b: 2}}
+            in {a: {a: 0}}
+              false
+            in {a: {a: 1}, b: {b: 1}}
+              false
+            in {a: {a: 1}, b: {b: 2}}
+              true
+          end
+        RUBY
+
+        eval(<<~RUBY).should == true
+          case [{a: 1, b: [1]}, {a: 1, c: ["2"]}]
+            in [{a:, c:},]
+              false
+            in [{a: 1, b:}, {a: 1, c: [Integer]}]
+              false
+            in [_, {a: 1, c: [String]}]
+              true
+          end
+        RUBY
+      end
     end
 
     describe "refinements" do