Honor an applications env variables

Removing unused code and making the shell command more flexible. The
unused in this repo code is required in the downstream tc-Server repo
where it is doing the wrong thing.

[#90500196]

Author: Christopher Frost

lib/java_buildpack/component/immutable_java_home.rb

@@ -42,20 +42,6 @@ def as_env_var
         "JAVA_HOME=#{root}"
       end
 
-      # Execute a block with the +JAVA_HOME+ environment variable set
-      #
-      # @yield yields to block with the +JAVA_HOME+ environment variable set
-      # @return [Object] the returned value of the block
-      def do_with
-        previous_value = ENV['JAVA_HOME']
-        begin
-          ENV['JAVA_HOME'] = @delegate.root.cleanpath.to_s
-          yield
-        ensure
-          ENV['JAVA_HOME'] = previous_value
-        end
-      end
-
       # @return [String] the root of the droplet's +JAVA_HOME+ formatted as +$PWD/<value>+
       def root
         qualify_path @delegate.root

lib/java_buildpack/util/shell.rb

@@ -25,12 +25,12 @@ module Shell
 
       # A +system()+-like command that ensure that the execution fails if the command returns a non-zero exit code
       #
-      # @param [String] command the command to run
+      # @param [Object] args The command to run
       # @return [Void]
-      def shell(command)
-        Open3.popen3(command) do |_stdin, stdout, stderr, wait_thr|
+      def shell(*args)
+        Open3.popen3(*args) do |_stdin, stdout, stderr, wait_thr|
           if wait_thr.value != 0
-            puts "\nCommand '#{command}' has failed"
+            puts "\nCommand '#{args.join ' '}' has failed"
             puts "STDOUT: #{stdout.gets}"
             puts "STDERR: #{stderr.gets}"
 

spec/java_buildpack/component/immutable_java_home_spec.rb

@@ -27,12 +27,6 @@
     expect(immutable_java_home.as_env_var).to eq('JAVA_HOME=$PWD/test-java-home')
   end
 
-  it 'sets JAVA_HOME environment variable' do
-    immutable_java_home.do_with do
-      expect(ENV['JAVA_HOME']).to eq('test-java-home')
-    end
-  end
-
   it 'returns the qualified delegate root' do
     expect(immutable_java_home.root).to eq('$PWD/test-java-home')
   end