Allow alternate version to be specified from command line

Author: Kevin Paulisse

octocatalog-diff.gemspec

@@ -6,7 +6,7 @@ Gem::Specification.new do |s|
   s.required_ruby_version = '>= 2.0.0'
 
   s.name        = 'octocatalog-diff'
-  s.version     = OctocatalogDiff::Version::VERSION
+  s.version     = ENV['OCTOCATALOG_DIFF_VERSION'] || OctocatalogDiff::Version::VERSION
   s.license     = 'MIT'
   s.authors     = ['GitHub, Inc.', 'Kevin Paulisse']
   s.email       = 'opensource+octocatalog-diff@github.com'

rake/gem.rb

@@ -6,8 +6,17 @@
 module OctocatalogDiff
   # A class to contain methods and constants for cleaner code
   class Gem
+    # Override version number from the environment
+    def self.version
+      version = ENV['OCTOCATALOG_DIFF_VERSION'] || OctocatalogDiff::Version::VERSION
+      unless version == OctocatalogDiff::Version::VERSION
+        warn "WARNING: Using version #{version}, not #{OctocatalogDiff::Version::VERSION}"
+      end
+      version
+    end
+
     BASEDIR = File.expand_path('..', File.dirname(__FILE__)).freeze
-    VERSION = OctocatalogDiff::Version::VERSION
+    VERSION = version.freeze
     GEMFILE = "octocatalog-diff-#{VERSION}.gem".freeze
     PKGDIR = File.join(BASEDIR, 'pkg').freeze
     OUTFILE = File.join(BASEDIR, GEMFILE).freeze
@@ -77,8 +86,12 @@ def self.exec_command(command)
 
   task 'force-build' do
     branch = OctocatalogDiff::Gem.branch
-    warn "WARNING: Force-building from non-master branch #{branch}" unless branch == 'master'
-    OctocatalogDiff::Gem.build("octocatalog-diff-#{OctocatalogDiff::Gem::VERSION}-#{branch}.gem")
+    unless branch == 'master'
+      warn "WARNING: Force-building from non-master branch #{branch}"
+    end
+
+    version = OctocatalogDiff::Gem.version
+    OctocatalogDiff::Gem.build("octocatalog-diff-#{version}-#{branch}.gem")
   end
 
   task 'push' do
@@ -127,7 +140,7 @@ def self.exec_command(command)
 
     # Make sure the gem has been built
     branch = OctocatalogDiff::Gem.branch
-    version = OctocatalogDiff::Gem::VERSION
+    version = OctocatalogDiff::Gem.version
     gemfile = if branch == 'master'
       OctocatalogDiff::Gem::FINAL_GEMFILE
     else