Add tests for terser

Author: johnnyshields

sprockets.gemspec

@@ -33,6 +33,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rake", "~> 13.2"
   s.add_development_dependency "sass", "~> 3.4"
   s.add_development_dependency "sassc", "~> 2.0"
+  s.add_development_dependency "terser", ">= 1.2"
   s.add_development_dependency "uglifier", ">= 2.3"
   s.add_development_dependency "yui-compressor", "~> 0.12"
   unless RUBY_PLATFORM.include?('java')

test/test_terser.rb

@@ -0,0 +1,122 @@
+# frozen_string_literal: true
+require 'minitest/autorun'
+require 'sprockets'
+require 'terser'
+
+class TestTerserCompressor < Minitest::Test
+  def setup
+    @env = Sprockets::Environment.new
+    @env.js_compressor = Terser.new
+    @cache = Sprockets::Cache.new
+
+    @tmpdir = Dir.mktmpdir
+    @env.append_path(@tmpdir)
+  end
+
+  def teardown
+    FileUtils.rm_rf(@tmpdir) if @tmpdir
+  end
+
+  def test_terser_configured_as_compressor
+    assert_equal :js_compressor, @env.js_compressor
+  end
+
+  def test_compress_javascript_through_sprockets
+    js_content = "function foo() {\n  return true;\n}"
+    file_path = File.join(@tmpdir, 'test.js')
+    File.write(file_path, js_content)
+
+    asset = @env['test.js']
+    compressed = asset.to_s
+
+    assert compressed.length < js_content.length
+    assert compressed.include?('function foo(){return!0}')
+    refute compressed.include?("\n  ")
+  end
+
+  def test_compress_es6_through_sprockets
+    js_content = "const arrow = (x) => {\n  return x * 2;\n}\nlet value = 10;"
+    file_path = File.join(@tmpdir, 'test_es6.js')
+    File.write(file_path, js_content)
+
+    asset = @env['test_es6.js']
+    compressed = asset.to_s
+
+    assert compressed.length < js_content.length
+    assert compressed.include?('const arrow=a=>2*a')
+    refute compressed.include?("\n  ")
+  end
+
+  def test_compress_with_comments_through_sprockets
+    js_content = <<~JS
+      // This is a single line comment
+      function calculate(a, b) {
+        /* This is a 
+           multi-line comment */
+        return a + b;
+      }
+    JS
+
+    file_path = File.join(@tmpdir, 'test_comments.js')
+    File.write(file_path, js_content)
+
+    asset = @env['test_comments.js']
+    compressed = asset.to_s
+
+    assert compressed.length < js_content.length
+    refute compressed.include?('This is a single line comment')
+    refute compressed.include?('multi-line comment')
+    assert compressed.include?('function calculate')
+  end
+
+  def test_preserve_license_comments_through_sprockets
+    js_content = <<~JS
+      /*! 
+       * Important License Information
+       * Copyright (c) 2024
+       */
+      function licensed() {
+        return "code";
+      }
+    JS
+
+    file_path = File.join(@tmpdir, 'test_license.js')
+    File.write(file_path, js_content)
+
+    asset = @env['test_license.js']
+    compressed = asset.to_s
+
+    assert compressed.length < js_content.length
+    assert compressed.include?('function licensed')
+  end
+
+  def test_multiple_files_compression
+    file1_content = "var globalVar = 100;\nfunction first() { return globalVar; }"
+    file2_content = "function second() { return globalVar * 2; }"
+
+    File.write(File.join(@tmpdir, 'file1.js'), file1_content)
+    File.write(File.join(@tmpdir, 'file2.js'), file2_content)
+
+    asset1 = @env['file1.js']
+    asset2 = @env['file2.js']
+
+    compressed1 = asset1.to_s
+    compressed2 = asset2.to_s
+
+    assert compressed1.length < file1_content.length
+    assert compressed2.length < file2_content.length
+
+    assert compressed1.include?('globalVar')
+    assert compressed2.include?('globalVar')
+  end
+
+  def test_compression_with_syntax_error
+    js_content = 'function broken() { this is not valid javascript'
+    file_path = File.join(@tmpdir, 'test_error.js')
+    File.write(file_path, js_content)
+
+    assert_raises(Terser::Error) do
+      @env['test_error.js'].to_s
+    end
+  end
+end