Add a few tests

ruby/test.rb

@@ -0,0 +1,97 @@
+#!/usr/bin/env ruby -w
+
+require 'minitest/autorun'
+
+class ShellTest < Minitest::Test
+  TRIVIAL_SHELL_SCRIPT = "#!/bin/sh\ntrue".freeze
+
+  def setup
+    FileUtils.mkdir_p('test_bin')
+  end
+
+  def teardown
+    FileUtils.rm_rf('test_bin')
+  end
+
+  def unique_shell_script(code)
+    "#!/bin/sh\necho '#{code}'"
+  end
+
+  def test_expands_environment_variables
+    assert_equal ENV['HOME'], `./a1 -c 'echo $HOME'`.chomp
+    assert system("./a1 -c 'echo $HOME' >/dev/null")
+  end
+
+  def test_fails_on_unknown_variables
+    assert_equal false, system("./a1 -c 'echo $DEFINITELY_DOES_NOT_EXIST' 2>/dev/null")
+  end
+
+  #################################
+  ### Execution and job control ###
+  #################################
+
+  def test_background_job
+    output = `./a1 -c 'bg echo hello'`
+    assert output.match?(/\ABackground job 1 \(pid \d+\)\nhello\n\z/m), "'#{output}' is unexpected"
+  end
+
+  def test_resolves_executables_with_absolute_paths
+    assert_equal '/usr/bin/which', `./a1 -c '/usr/bin/which -a which'`.chomp
+  end
+
+  def test_resolves_executables_with_relative_paths
+    File.write('test_bin/something', TRIVIAL_SHELL_SCRIPT)
+    File.chmod(0o755, 'test_bin/something')
+    assert system('./a1 -c ./test_bin/something')
+  end
+
+  def test_resolves_executables_in_absolute_paths
+    assert_equal '/usr/bin/which', `./a1 -c 'which -a which'`.chomp
+  end
+
+  def test_resolves_executables_in_relative_paths
+    code = rand(1_000_000).to_s
+    File.write('test_bin/definitely_executable', unique_shell_script(code))
+    File.chmod(0o755, 'test_bin/definitely_executable')
+    actual = `PATH="./test_bin:$PATH" ./a1 -c definitely_executable`.chomp
+    assert_equal code, actual
+  end
+
+  def test_does_not_resolve_non_executable_files_in_path
+    File.write('test_bin/definitely_not_executable', TRIVIAL_SHELL_SCRIPT)
+    File.chmod(0o644, 'test_bin/definitely_not_executable')
+    actual = system('PATH="./test_bin:$PATH" ./a1 -c definitely_not_executable 2>/dev/null')
+    assert_equal false, actual
+  end
+
+  def test_refreshes_readline_after_bg_execution
+    skip 'unimplemented'
+  end
+
+  #########################
+  ### Built-in commands ###
+  #########################
+
+  def test_builtin_cd_no_args
+    skip 'cannot easily implement without sequencing with ; or &&'
+  end
+
+  def test_builtin_cd
+    skip 'cannot easily implement without sequencing with ; or &&'
+  end
+
+  def test_builtin_cd_dash
+    skip 'cannot easily implement without sequencing with ; or &&'
+  end
+
+  def test_builtin_cd_parent
+    skip 'cannot easily implement without sequencing with ; or &&'
+  end
+
+  def test_builtin_pwd
+    assert_equal Dir.pwd, `./a1 -c pwd`.chomp
+
+    shell_path = File.expand_path('a1', __dir__)
+    assert_equal '/usr/bin', `cd /usr/bin && '#{shell_path}' -c pwd`.chomp
+  end
+end