1 files changed, 62 insertions, 0 deletions
diff --git a/spec/ruby/core/proc/lambda_spec.rb b/spec/ruby/core/proc/lambda_spec.rb
new file mode 100644
index 0000000000..5c3c38fc2a
--- /dev/null
+++ b/spec/ruby/core/proc/lambda_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/common'
+
+describe "Proc#lambda?" do
+  it "returns true if the Proc was created from a block with the lambda keyword" do
+    -> {}.lambda?.should be_true
+  end
+
+  it "returns false if the Proc was created from a block with the proc keyword" do
+    proc {}.lambda?.should be_false
+  end
+
+  it "returns false if the Proc was created from a block with Proc.new" do
+    Proc.new {}.lambda?.should be_false
+  end
+
+  ruby_version_is ""..."3.3" do
+    it "is preserved when passing a Proc with & to the lambda keyword" do
+      suppress_warning {lambda(&->{})}.lambda?.should be_true
+      suppress_warning {lambda(&proc{})}.lambda?.should be_false
+    end
+  end
+
+  it "is preserved when passing a Proc with & to the proc keyword" do
+    proc(&->{}).lambda?.should be_true
+    proc(&proc{}).lambda?.should be_false
+  end
+
+  it "is preserved when passing a Proc with & to Proc.new" do
+    Proc.new(&->{}).lambda?.should be_true
+    Proc.new(&proc{}).lambda?.should be_false
+  end
+
+  it "returns false if the Proc was created from a block with &" do
+    ProcSpecs.new_proc_from_amp{}.lambda?.should be_false
+  end
+
+  it "is preserved when the Proc was passed using &" do
+    ProcSpecs.new_proc_from_amp(&->{}).lambda?.should be_true
+    ProcSpecs.new_proc_from_amp(&proc{}).lambda?.should be_false
+    ProcSpecs.new_proc_from_amp(&Proc.new{}).lambda?.should be_false
+  end
+
+  it "returns true for a Method converted to a Proc" do
+    m = :foo.method(:to_s)
+    m.to_proc.lambda?.should be_true
+    ProcSpecs.new_proc_from_amp(&m).lambda?.should be_true
+  end
+
+  # [ruby-core:24127]
+  it "is preserved when a Proc is curried" do
+    ->{}.curry.lambda?.should be_true
+    proc{}.curry.lambda?.should be_false
+    Proc.new{}.curry.lambda?.should be_false
+  end
+
+  it "is preserved when a curried Proc is called without enough arguments" do
+    -> x, y{}.curry.call(42).lambda?.should be_true
+    proc{|x,y|}.curry.call(42).lambda?.should be_false
+    Proc.new{|x,y|}.curry.call(42).lambda?.should be_false
+  end
+end