1 files changed, 102 insertions, 4 deletions
diff --git a/spec/ruby/core/env/merge_spec.rb b/spec/ruby/core/env/merge_spec.rb
index b418cd11f4..78231afbb2 100644
--- a/spec/ruby/core/env/merge_spec.rb
+++ b/spec/ruby/core/env/merge_spec.rb
@@ -1,8 +1,106 @@
 require_relative '../../spec_helper'
-require_relative 'shared/update'
 
-ruby_version_is "2.7" do
-  describe "ENV.merge!" do
-    it_behaves_like :env_update, :merge!
+describe "ENV.merge!" do
+  before :each do
+    @saved_foo = ENV["foo"]
+    @saved_bar = ENV["bar"]
+  end
+
+  after :each do
+    ENV["foo"] = @saved_foo
+    ENV["bar"] = @saved_bar
+  end
+
+  it "adds the parameter hash to ENV, returning ENV" do
+    ENV.merge!("foo" => "0", "bar" => "1").should.equal?(ENV)
+    ENV["foo"].should == "0"
+    ENV["bar"].should == "1"
+  end
+
+  it "adds the multiple parameter hashes to ENV, returning ENV" do
+    ENV.merge!({"foo" => "multi1"}, {"bar" => "multi2"}).should.equal?(ENV)
+    ENV["foo"].should == "multi1"
+    ENV["bar"].should == "multi2"
+  end
+
+  it "returns ENV when no block given" do
+    ENV.merge!({"foo" => "0", "bar" => "1"}).should.equal?(ENV)
+  end
+
+  it "yields key, the old value and the new value when replacing an entry" do
+    ENV.merge!({"foo" => "0", "bar" => "3"})
+    a = []
+    ENV.merge!({"foo" => "1", "bar" => "4"}) do |key, old, new|
+      a << [key, old, new]
+      new
+    end
+    a[0].should == ["foo", "0", "1"]
+    a[1].should == ["bar", "3", "4"]
+  end
+
+  it "yields key, the old value and the new value when replacing an entry" do
+    ENV.merge!({"foo" => "0", "bar" => "3"})
+    ENV.merge!({"foo" => "1", "bar" => "4"}) do |key, old, new|
+      (new.to_i + 1).to_s
+    end
+    ENV["foo"].should == "2"
+    ENV["bar"].should == "5"
+  end
+
+  # BUG: https://bugs.ruby-lang.org/issues/16192
+  it "does not evaluate the block when the name is new" do
+    ENV.delete("bar")
+    ENV.merge!({"foo" => "0"})
+    ENV.merge!("bar" => "1") { |key, old, new| fail "Should not get here" }
+    ENV["bar"].should == "1"
+  end
+
+  # BUG: https://bugs.ruby-lang.org/issues/16192
+  it "does not use the block's return value as the value when the name is new" do
+    ENV.delete("bar")
+    ENV.merge!({"foo" => "0"})
+    ENV.merge!("bar" => "1") { |key, old, new| "Should not use this value" }
+    ENV["foo"].should == "0"
+    ENV["bar"].should == "1"
+  end
+
+  it "returns ENV when block given" do
+    ENV.merge!({"foo" => "0", "bar" => "1"}){}.should.equal?(ENV)
+  end
+
+  it "raises TypeError when a name is not coercible to String" do
+    -> { ENV.merge!(Object.new => "0") }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
+
+  it "raises TypeError when a value is not coercible to String" do
+    -> { ENV.merge!("foo" => Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
+
+  it "raises Errno::EINVAL when a name contains the '=' character" do
+    -> { ENV.merge!("foo=" => "bar") }.should.raise(Errno::EINVAL)
+  end
+
+  it "raises Errno::EINVAL when a name is an empty string" do
+    -> { ENV.merge!("" => "bar") }.should.raise(Errno::EINVAL)
+  end
+
+  it "updates good data preceding an error" do
+    ENV["foo"] = "0"
+    begin
+      ENV.merge!({"foo" => "2", Object.new => "1"})
+    rescue TypeError
+    ensure
+      ENV["foo"].should == "2"
+    end
+  end
+
+  it "does not update good data following an error" do
+    ENV["foo"] = "0"
+    begin
+      ENV.merge!({Object.new => "1", "foo" => "2"})
+    rescue TypeError
+    ensure
+      ENV["foo"].should == "0"
+    end
   end
 end