1 files changed, 147 insertions, 0 deletions
diff --git a/spec/ruby/language/safe_navigator_spec.rb b/spec/ruby/language/safe_navigator_spec.rb
new file mode 100644
index 0000000000..e8b429631d
--- /dev/null
+++ b/spec/ruby/language/safe_navigator_spec.rb
@@ -0,0 +1,147 @@
+require_relative '../spec_helper'
+
+describe "Safe navigator" do
+  it "requires a method name to be provided" do
+    -> { eval("obj&. {}") }.should.raise(SyntaxError)
+  end
+
+  context "when context is nil" do
+    it "always returns nil" do
+      nil&.unknown.should == nil
+      [][10]&.unknown.should == nil
+    end
+
+    it "can be chained" do
+      nil&.one&.two&.three.should == nil
+    end
+
+    it "doesn't evaluate arguments" do
+      obj = Object.new
+      obj.should_not_receive(:m)
+      nil&.unknown(obj.m) { obj.m }
+    end
+  end
+
+  context "when context is false" do
+    it "calls the method" do
+      false&.to_s.should == "false"
+
+      -> { false&.unknown }.should.raise(NoMethodError)
+    end
+  end
+
+  context "when context is truthy" do
+    it "calls the method" do
+      1&.to_s.should == "1"
+
+      -> { 1&.unknown }.should.raise(NoMethodError)
+    end
+  end
+
+  it "takes a list of arguments" do
+    [1,2,3]&.first(2).should == [1,2]
+  end
+
+  it "takes a block" do
+    [1,2]&.map { |i| i * 2 }.should == [2, 4]
+  end
+
+  it "allows assignment methods" do
+    klass = Class.new do
+      attr_reader :foo
+      def foo=(val)
+        @foo = val
+        42
+      end
+    end
+    obj = klass.new
+
+    (obj&.foo = 3).should == 3
+    obj.foo.should == 3
+
+    obj = nil
+    (obj&.foo = 3).should == nil
+  end
+
+  it "allows assignment operators" do
+    klass = Class.new do
+      attr_reader :m
+
+      def initialize
+        @m = 0
+      end
+
+      def m=(v)
+        @m = v
+        42
+      end
+    end
+
+    obj = klass.new
+
+    obj&.m += 3
+    obj.m.should == 3
+
+    obj = nil
+    (obj&.m += 3).should == nil
+  end
+
+  it "allows ||= operator" do
+    klass = Class.new do
+      attr_reader :m
+
+      def initialize
+        @m = false
+      end
+
+      def m=(v)
+        @m = v
+        42
+      end
+    end
+
+    obj = klass.new
+
+    (obj&.m ||= true).should == true
+    obj.m.should == true
+
+    obj = nil
+    (obj&.m ||= true).should == nil
+    obj.should == nil
+  end
+
+  it "allows &&= operator" do
+    klass = Class.new do
+      attr_accessor :m
+
+      def initialize
+        @m = true
+      end
+    end
+
+    obj = klass.new
+
+    (obj&.m &&= false).should == false
+    obj.m.should == false
+
+    obj = nil
+    (obj&.m &&= false).should == nil
+    obj.should == nil
+  end
+
+  it "does not call the operator method lazily with an assignment operator" do
+    klass = Class.new do
+      attr_writer :foo
+      def foo
+        nil
+      end
+    end
+    obj = klass.new
+
+    -> {
+      obj&.foo += 3
+    }.should.raise(NoMethodError) { |e|
+      e.name.should == :+
+    }
+  end
+end