ruby: add test of rb/uninitialized-local-variable

ruby/ql/test/query-tests/variables/UninitializedLocal/UninitializedLocal.rb

@@ -0,0 +1,46 @@
+def m
+  puts "m"
+end
+
+def foo
+  m # calls m above
+  if false
+      m = 0
+      m # reads local variable m
+  else
+  end
+  m  #$ Alert
+  m2 # undefined local variable or method 'm2' for main (NameError)
+end
+
+def test_guards
+  if (a = 3 && a)  #$ Alert
+      a
+  end
+  if (a = 3) && a  # OK - a is assigned in the previous conjunct
+      a
+  end
+  if !(a = 3) or a  # OK - a is assigned in the previous conjunct
+      a
+  end
+  if false
+      b = 0
+  end
+  b.nil?
+  b || 0  #$ SPURIOUS: Alert
+  b&.m  #$ SPURIOUS: Alert
+  b if b  #$ SPURIOUS: Alert
+  b.close if b && !b.closed #$ SPURIOUS: Alert
+  b.blowup if b || !b.blownup #$ Alert
+end
+
+def test_loop
+  begin
+      if false
+          a = 0
+      else
+          set_a
+      end   
+  end until a  #$ SPURIOUS: Alert
+  a  #$ SPURIOUS: Alert
+end