Add tests for block_given? desugaring (sorbet#9723)

Author: amomchilov

test/testdata/desugar/block_given.rb

@@ -0,0 +1,54 @@
+# typed: false
+
+class SomethingElse; end
+
+def method_with_block_param(&the_block_name)
+  # Valid cases that we should detect as special calls to `block_given?`
+  block_given?
+  self.block_given?
+  Kernel.block_given?
+  ::Kernel.block_given?
+
+  # Due to the current structure of Desugar.cc, we still detect this as a special `block_given?` call.
+  block_given? { "with a block?!" }
+  #            ^^^^^^^^^^^^^^^^^^^^ error: No body in block
+
+  # Cases we should not detect as special calls to `block_given?`
+  Object.block_given? # Normally not allowed: private method `block_given?' called for Object:Class
+  SomethingElse.block_given?
+  block_given?("with parameter")
+end
+
+def method_with_anonymous_block_param(&)
+  # Valid cases that we should detect as special calls to `block_given?`
+  block_given?
+  self.block_given?
+  Kernel.block_given?
+  ::Kernel.block_given?
+
+  # Due to the current structure of Desugar.cc, we still detect this as a special `block_given?` call.
+  block_given? { "with a block?!" }
+  #            ^^^^^^^^^^^^^^^^^^^^ error: No body in block
+
+  # Cases we should not detect as special calls to `block_given?`
+  Object.block_given? # Normally not allowed: private method `block_given?' called for Object:Class
+  SomethingElse.block_given?
+  block_given?("with parameter")
+end
+
+def method_with_implicit_block_param()
+  # Valid cases that we should detect as special calls to `block_given?`
+  block_given?
+  self.block_given?
+  Kernel.block_given?
+  ::Kernel.block_given?
+
+  # Due to the current structure of Desugar.cc, we still detect this as a special `block_given?` call.
+  block_given? { "with a block?!" }
+  #            ^^^^^^^^^^^^^^^^^^^^ error: No body in block
+
+  # Cases we should not detect as special calls to `block_given?`
+  Object.block_given? # Normally not allowed: private method `block_given?' called for Object:Class
+  SomethingElse.block_given?
+  block_given?("with parameter")
+end

test/testdata/desugar/block_given.rb.desugar-tree.exp

@@ -0,0 +1,116 @@
+class <emptyTree><<C <root>>> < (::<todo sym>)
+  class <emptyTree>::<C SomethingElse><<C <todo sym>>> < (::<todo sym>)
+    <emptyTree>
+  end
+
+  def method_with_block_param<<todo method>>(&the_block_name)
+    begin
+      if the_block_name
+        <self>.block_given?()
+      else
+        false
+      end
+      if the_block_name
+        <self>.block_given?()
+      else
+        false
+      end
+      if the_block_name
+        <emptyTree>::<C Kernel>.block_given?()
+      else
+        false
+      end
+      if the_block_name
+        ::<root>::<C Kernel>.block_given?()
+      else
+        false
+      end
+      <emptyTree>
+      if the_block_name
+        <emptyTree>::<C Object>.block_given?()
+      else
+        false
+      end
+      if the_block_name
+        <emptyTree>::<C SomethingElse>.block_given?()
+      else
+        false
+      end
+      <self>.block_given?("with parameter")
+    end
+  end
+
+  def method_with_anonymous_block_param<<todo method>>(&&$2)
+    begin
+      if &$2
+        <self>.block_given?()
+      else
+        false
+      end
+      if &$2
+        <self>.block_given?()
+      else
+        false
+      end
+      if &$2
+        <emptyTree>::<C Kernel>.block_given?()
+      else
+        false
+      end
+      if &$2
+        ::<root>::<C Kernel>.block_given?()
+      else
+        false
+      end
+      <emptyTree>
+      if &$2
+        <emptyTree>::<C Object>.block_given?()
+      else
+        false
+      end
+      if &$2
+        <emptyTree>::<C SomethingElse>.block_given?()
+      else
+        false
+      end
+      <self>.block_given?("with parameter")
+    end
+  end
+
+  def method_with_implicit_block_param<<todo method>>(&<blk>)
+    begin
+      if <blk>
+        <self>.block_given?()
+      else
+        false
+      end
+      if <blk>
+        <self>.block_given?()
+      else
+        false
+      end
+      if <blk>
+        <emptyTree>::<C Kernel>.block_given?()
+      else
+        false
+      end
+      if <blk>
+        ::<root>::<C Kernel>.block_given?()
+      else
+        false
+      end
+      <emptyTree>
+      if <blk>
+        <emptyTree>::<C Object>.block_given?()
+      else
+        false
+      end
+      if <blk>
+        <emptyTree>::<C SomethingElse>.block_given?()
+      else
+        false
+      end
+      <self>.block_given?("with parameter")
+    end
+  end
+end