Fixed "Comparable#== will no more rescue exceptions of #<=>" (bsc#933…

…470)

Term and Path would raise exceptions when <=> was used to compare them
with something that was not a Term or Path.

In particular it happened during RSpec argument matching.

In older Ruby core, Comparable#== would silently mask such exceptions,
now it started producing warnings.
https://bugs.ruby-lang.org/issues/7688

src/ruby/yast/path.rb

@@ -43,6 +43,7 @@ def empty?
     end
 
     def <=>(other)
+      return nil unless other.is_a? self.class
       0.upto(size-1) do |i|
         return 1 unless other.send(:components)[i]
         #we strip enclosing quotes for complex expression

src/ruby/yast/term.rb

@@ -88,6 +88,7 @@ def to_s
     end
 
     def <=> (other)
+      return nil unless other.is_a? self.class
       res = value <=> other.value
       return res if res != 0
 

tests/ruby/path_spec.rb

@@ -48,6 +48,11 @@
       expect(Yast::Path.new('.ba')).to be >= Yast::Path.new('."a?"')
       expect(Yast::Path.new('."b?"')).to be >= Yast::Path.new('.ab')
     end
+
+    # bsc#933470
+    it "survives comparison with a non-Path" do
+      expect(Yast::Path.new('.foo') <=> 42).to eq nil
+    end
   end
 
   describe "#clone" do

tests/ruby/term_spec.rb

@@ -1,10 +1,6 @@
 #!/usr/bin/env rspec
 # encoding: utf-8
 
-# FIXME: this file was autoconverted from test/unit syntax without
-# adjusting it to good RSpec style (http://betterspecs.org/).
-# Please improve it whenever adding examples.
-
 require_relative "test_helper"
 
 require "yast/term"
@@ -47,15 +43,15 @@ def term(*params)
     end
   end
 
-  describe "#<<" do
+  describe "#<<" do             #  " <- unconfuse Emacs string highlighting
     it "appends parameter to params" do
       t = term(:HBox, 1, 2)
       t << 3
       expect(t[2]).to eq(3)
     end
   end
 
-  describe "comparison" do
+  describe "#<=> (comparison)" do
     it "if value and params are equal, then it is equal terms" do
       expect(term(:HBox)).to eq(term(:HBox))
     end
@@ -75,6 +71,10 @@ def term(*params)
     it "if value is equal, then use params to comparison" do
       expect(term(:HBox, "test")).to be > term(:HBox)
     end
+
+    it "if non-term, then uncomparable" do
+      expect(term(:HBox, "test") <=> 42).to eq nil
+    end
   end
 
   describe "#size" do