Improved handling of Semver pre-release versions

CHANGELOG.md

@@ -4,7 +4,9 @@
 
 ##### Enhancements
 
-* None.  
+* Improved comparison between Semver pre-release versions.  
+  [Ben Asher](https://github.com/benasher44)
+  [#350](https://github.com/CocoaPods/Core/pull/350)
 
 ##### Bug Fixes
 

lib/cocoapods-core/version.rb

@@ -194,22 +194,33 @@ def compare_segments(other)
       return unless other.is_a?(Pod::Version)
       return 0 if @version == other.version
 
-      compare = proc do |segments, other_segments|
+      compare = proc do |segments, other_segments, is_pre_release|
         limit = [segments.size, other_segments.size].max
 
         (0..limit).each do |i|
-          lhs = segments[i] || 0
-          rhs = other_segments[i] || 0
+          lhs = segments[i]
+          rhs = other_segments[i]
 
           next if lhs == rhs
+          # If it's pre-release and the first segment, then
+          # this is a special case because a segment missing
+          # means that one is not a pre-release version
+          if is_pre_release && i == 0
+            return 1 if lhs.nil?
+            return -1 if rhs.nil?
+          else
+            return -1 if lhs.nil?
+            return  1 if rhs.nil?
+          end
+
           return lhs <=> rhs if lhs <=> rhs
-          return -1 if lhs.is_a?(String) && rhs.is_a?(Numeric)
-          return  1 if lhs.is_a?(Numeric) && rhs.is_a?(String)
+          return 1 if lhs.is_a?(String) && rhs.is_a?(Numeric)
+          return -1 if lhs.is_a?(Numeric) && rhs.is_a?(String)
         end
       end
 
-      compare[numeric_segments, other.numeric_segments]
-      compare[prerelease_segments, other.prerelease_segments]
+      compare[numeric_segments, other.numeric_segments, false]
+      compare[prerelease_segments, other.prerelease_segments, true]
       0
     end
 

spec/version_spec.rb

@@ -95,6 +95,13 @@ module Pod
         Version.new('1.alpha.2').patch.should == 0
       end
 
+      it 'correctly makes basic version comparisons' do
+        Version.new('1.0.0').should.be < Version.new('2.0.0')
+        Version.new('1.0.0').should.be < Version.new('1.0.1')
+        Version.new('1.0.0').should.be < Version.new('1.1.0')
+        Version.new('1.1.0').should.be < Version.new('1.1.1')
+      end
+
       it 'ignores missing numeric identifiers while comparing' do
         Version.new('1.9.0-alpha').should.be < Version.new('1.9-beta')
         Version.new('2.0.0-beta').should.be < Version.new('2.0-rc')
@@ -107,6 +114,20 @@ module Pod
         Version.new('1.0-alpha').should.be < Version.new('1.0.0-alpha')
         Version.new('1.1.1.1-alpha').should.be < Version.new('1.1.1.1.0-alpha')
       end
+
+      it 'Follows semver when comparing between pre-release versions' do
+        # Example from section 11 on semver.org
+        Version.new('1.0.0-alpha').should.be < Version.new('1.0.0-alpha.1')
+        Version.new('1.0.0-alpha.1').should.be < Version.new('1.0.0-alpha.beta')
+        Version.new('1.0.0-alpha.beta').should.be < Version.new('1.0.0-beta')
+        Version.new('1.0.0-beta').should.be < Version.new('1.0.0-beta.2')
+        Version.new('1.0.0-beta.2').should.be < Version.new('1.0.0-beta.11')
+        Version.new('1.0.0-beta.11').should.be < Version.new('1.0.0-rc.1')
+        Version.new('1.0.0-rc.1').should.be < Version.new('1.0.0')
+
+        # Example from CocoaPods/CocoaPods#5718
+        Version.new('1.0-beta.8').should.be < Version.new('1.0-beta.8a')
+      end
     end
 
     #-------------------------------------------------------------------------#