1 files changed, 95 insertions, 6 deletions
diff --git a/spec/ruby/library/stringscanner/exist_spec.rb b/spec/ruby/library/stringscanner/exist_spec.rb
index ff860a0d3e..2207622366 100644
--- a/spec/ruby/library/stringscanner/exist_spec.rb
+++ b/spec/ruby/library/stringscanner/exist_spec.rb
@@ -2,11 +2,11 @@ require_relative '../../spec_helper'
 require 'strscan'
 
 describe "StringScanner#exist?" do
-  before :each do
+  before do
     @s = StringScanner.new("This is a test")
   end
 
-  it "returns the index of the first occurrence of the given pattern" do
+  it "returns distance in bytes between the current position and the end of the matched substring" do
     @s.exist?(/s/).should == 4
     @s.scan(/This is/)
     @s.exist?(/s/).should == 6
@@ -22,9 +22,98 @@ describe "StringScanner#exist?" do
     @s.exist?(/i/).should == nil
   end
 
-  it "raises TypeError if given a String" do
-    -> {
-      @s.exist?('T')
-    }.should raise_error(TypeError, 'wrong argument type String (expected Regexp)')
+  it "does not modify the current position" do
+    @s.pos.should == 0
+    @s.exist?(/s/).should == 4
+    @s.pos.should == 0
+  end
+
+  version_is StringScanner::Version, ""..."3.1.1" do # ruby_version_is ""..."3.4"
+    it "raises TypeError if given a String" do
+      -> {
+        @s.exist?('T')
+      }.should.raise(TypeError, 'wrong argument type String (expected Regexp)')
+    end
+  end
+
+  version_is StringScanner::Version, "3.1.1" do # ruby_version_is "3.4"
+    it "searches a substring in the rest part of a string if given a String" do
+      @s.exist?('a').should == 9
+    end
+
+    it "returns nil if the pattern isn't found in the string" do
+      @s.exist?("S").should == nil
+    end
+  end
+
+  describe "#[] successive call with a capture group name" do
+    context "when #exist? was called with a Regexp pattern" do
+      it "returns matched substring when matching succeeded" do
+        @s.exist?(/(?<a>This)/)
+        @s.should.matched?
+        @s[:a].should == "This"
+      end
+
+      it "returns nil when matching failed" do
+        @s.exist?(/(?<a>2008)/)
+        @s.should_not.matched?
+        @s[:a].should == nil
+      end
+    end
+
+    version_is StringScanner::Version, "3.1.1" do # ruby_version_is "3.4"
+      context "when #exist? was called with a String pattern" do
+        # https://github.com/ruby/strscan/issues/139
+        version_is StringScanner::Version, "3.1.1"..."3.1.3" do # ruby_version_is "3.4.0"..."3.4.3"
+          it "returns nil when matching succeeded" do
+            @s.exist?("This")
+            @s.should.matched?
+            @s[:a].should == nil
+          end
+        end
+        version_is StringScanner::Version, "3.1.3" do # ruby_version_is "3.4.3"
+          it "raises IndexError when matching succeeded" do
+            @s.exist?("This")
+            @s.should.matched?
+            -> { @s[:a] }.should.raise(IndexError)
+          end
+        end
+
+        it "returns nil when matching failed" do
+          @s.exist?("2008")
+          @s.should_not.matched?
+          @s[:a].should == nil
+        end
+
+        it "returns a matching substring when given Integer index" do
+          @s.exist?("This")
+          @s[0].should == "This"
+        end
+
+        # https://github.com/ruby/strscan/issues/135
+        version_is StringScanner::Version, "3.1.1"..."3.1.3" do # ruby_version_is "3.4.0"..."3.4.3"
+          it "ignores the previous matching with Regexp" do
+            @s.exist?(/(?<a>This)/)
+            @s.should.matched?
+            @s[:a].should == "This"
+
+            @s.exist?("This")
+            @s.should.matched?
+            @s[:a].should == nil
+          end
+        end
+        version_is StringScanner::Version, "3.1.3" do # ruby_version_is "3.4.0"..."3.4.3"
+          it "ignores the previous matching with Regexp" do
+            @s.exist?(/(?<a>This)/)
+            @s.should.matched?
+            @s[:a].should == "This"
+
+            @s.exist?("This")
+            @s.should.matched?
+            -> { @s[:a] }.should.raise(IndexError)
+          end
+        end
+      end
+    end
   end
 end