feat(test): Tests for custom install dir

ref: issue #34

test/features/step_definitions/general.rb

@@ -17,11 +17,30 @@ When('we run fish script') do |script_content|
     raise "Fish command failed: #{out}"
   end
 
-  @response_fish_script = out.strip
+  @output_fish_script = out.strip
 end
 
 Then(/^the output is$/) do |text|
-  expect(@response_fish_script).to eq(text.strip)
+  expect(@output_fish_script).to eq(text.strip)
+end
+
+When('we run {string} in Fish') do |command|
+  @response = run_fish_command(command)
+end
+
+Then('the exit code is {int}') do |code|
+  expect(@response[:status]).to eq(code)
+end
+
+Then(/^environment variable ([A-Z_]+) has value "([^"]+)"$/) do |key, value|
+  expect(@response[:env][key]).to eq(value)
+end
+
+And('the output contains {string}') do |content|
+  output = @response[:stdout]
+             .select { |line| !line.blank? }
+             .map { |line| line.strip }
+  expect(output).to include(content)
 end
 
 Then(/^file ([a-zA-Z0-9\-_.\/]+) contains$/) do |file,content|