Refactor shell runner (#20)

* Remove FixtureRunner in favor of fake Open3

* Use Open3.capture2e instead of Open3.capture3

Author: neilvcarvalho

lib/commands.rb

@@ -4,21 +4,8 @@
 require "json"
 
 module ImportmapUpdate
-  # Abstracts execution of external commands (bin/importmap) so the rest
-  # of the codebase doesn't shell out directly. This is the seam tests hook
-  # into — production code runs commands for real, tests inject a
-  # FixtureRunner that replays pre-recorded (argv → stdout, exit) tuples.
-  #
-  # The interface deliberately mirrors what Open3.capture3 returns:
-  #
-  #   runner.run("bin/importmap", "outdated")
-  #     # => Result(stdout: "...", stderr: "...", success: true, exit: 0)
-  #
-  # Commands are passed as an argv array, not a shell string. That's both
-  # safer (no shell-injection surprises from package names) and easier to
-  # match against fixture keys.
   module Commands
-    Result = Data.define(:stdout, :stderr, :exit_code) do
+    Result = Data.define(:output, :exit_code) do
       def success?
         exit_code == 0
       end
@@ -30,33 +17,24 @@ class CommandError < StandardError
       def initialize(argv, result)
         @argv = argv
         @result = result
-        super("`#{argv.join(" ")}` exited #{result.exit_code}: #{result.stderr.strip}")
+        super("`#{argv.join(" ")}` exited #{result.exit_code}: #{result.output.strip}")
       end
     end
 
-    # Production runner: actually executes the command.
     class ShellRunner
-      # @param cwd [String, nil] working directory (defaults to current)
-      def initialize(cwd: nil)
+      def initialize(cwd: nil, open3: Open3)
         @cwd = cwd
+        @open3 = open3
       end
 
       def run(*argv)
         opts = {}
         opts[:chdir] = @cwd if @cwd
         Bundler.with_unbundled_env do
-          stdout, stderr, status = Open3.capture3(*argv, opts)
-          Result.new(stdout:, stderr:, exit_code: status.exitstatus)
+          output, status = @open3.capture2e(*argv, **opts)
+          Result.new(output:, exit_code: status.exitstatus)
         end
       end
-
-      # Raises on non-zero exit. Use when you have no recovery strategy
-      # and just want to surface the error to the caller.
-      def run!(*argv)
-        result = run(*argv)
-        raise CommandError.new(argv, result) unless result.success?
-        result
-      end
     end
   end
 end

test/commands_test.rb

@@ -6,122 +6,17 @@
 class CommandsTest < Minitest::Test
   Commands = ImportmapUpdate::Commands
 
-  # ---- ShellRunner ----
-
   def test_shell_runner_captures_stdout
     result = Commands::ShellRunner.new.run("echo", "hello world")
-    assert_equal "hello world\n", result.stdout
+    assert_equal "hello world\n", result.output
     assert_predicate result, :success?
     assert_equal 0, result.exit_code
   end
 
   def test_shell_runner_captures_stderr_and_failure
-    # `sh -c` lets us write to stderr cleanly without depending on a
-    # specific binary's behavior.
     result = Commands::ShellRunner.new.run("sh", "-c", "echo oops 1>&2; exit 3")
-    assert_equal "oops\n", result.stderr
+    assert_equal "oops\n", result.output
     assert_equal 3, result.exit_code
     refute_predicate result, :success?
   end
-
-  def test_shell_runner_bang_raises_on_non_zero_exit
-    err = assert_raises(Commands::CommandError) do
-      Commands::ShellRunner.new.run!("sh", "-c", "echo nope 1>&2; exit 1")
-    end
-    assert_equal 1, err.result.exit_code
-    assert_includes err.message, "exited 1"
-    assert_includes err.message, "nope"
-  end
-
-  def test_shell_runner_argv_is_safe_from_shell_metacharacters
-    # argv-style invocation must not interpret `;` as a command separator.
-    # If it did, this test would attempt to delete a file.
-    result = Commands::ShellRunner.new.run("echo", "a; rm -rf /b")
-    assert_equal "a; rm -rf /b\n", result.stdout
-  end
-
-  # ---- FixtureRunner: literal matching ----
-
-  def test_fixture_runner_returns_recorded_result_for_exact_argv_match
-    runner = Commands::FixtureRunner.new
-    runner.add(
-      pattern: ["bin/importmap", "outdated"],
-      stdout: "| Package | Current | Latest |\n"
-    )
-    result = runner.run("bin/importmap", "outdated")
-    assert_equal "| Package | Current | Latest |\n", result.stdout
-    assert_predicate result, :success?
-  end
-
-  def test_fixture_runner_records_calls_in_order
-    runner = Commands::FixtureRunner.new
-    runner.add(pattern: ["bin/importmap", "outdated"], stdout: "")
-    runner.add(pattern: ["bin/importmap", "audit"], stdout: "")
-    runner.run("bin/importmap", "outdated")
-    runner.run("bin/importmap", "audit")
-    assert_equal [
-      ["bin/importmap", "outdated"],
-      ["bin/importmap", "audit"]
-    ], runner.calls
-  end
-
-  def test_fixture_runner_first_matching_pattern_wins
-    # Order matters: if you register a fallback first, it'll swallow more
-    # specific patterns. This test pins the behavior so callers know to
-    # register specific patterns before general ones.
-    runner = Commands::FixtureRunner.new
-    runner.add(pattern: ["bin/importmap", "pin", "lodash@4.17.21"], stdout: "first\n")
-    runner.add(pattern: ["bin/importmap", "pin", "lodash@4.17.21"], stdout: "second\n")
-    assert_equal "first\n", runner.run("bin/importmap", "pin", "lodash@4.17.21").stdout
-  end
-
-  # ---- FixtureRunner: regex matching ----
-
-  def test_fixture_runner_supports_regex_elements_in_patterns
-    # Package versions change; the pattern uses a regex to allow any semver.
-    runner = Commands::FixtureRunner.new
-    runner.add(
-      pattern: ["bin/importmap", "pin", /\Alodash@\d+\.\d+\.\d+\z/],
-      stdout: "Pinned lodash\n"
-    )
-    assert_equal "Pinned lodash\n", runner.run("bin/importmap", "pin", "lodash@4.17.21").stdout
-  end
-
-  def test_fixture_runner_regex_must_match_exactly_at_position
-    runner = Commands::FixtureRunner.new
-    runner.add(pattern: ["bin/importmap", "pin", /\Alodash@/], stdout: "ok\n")
-    err = assert_raises(RuntimeError) do
-      runner.run("bin/importmap", "pin", "axios@1.7.0")
-    end
-    assert_match(/No fixture matched/, err.message)
-  end
-
-  # ---- FixtureRunner: misses and errors ----
-
-  def test_fixture_runner_raises_clearly_when_no_pattern_matches
-    runner = Commands::FixtureRunner.new
-    runner.add(pattern: ["bin/importmap", "outdated"], stdout: "")
-    err = assert_raises(RuntimeError) { runner.run("bin/importmap", "audit") }
-    assert_includes err.message, "No fixture matched"
-    assert_includes err.message, "audit"
-  end
-
-  def test_fixture_runner_argv_size_mismatch_does_not_match
-    # A 2-element pattern must not match a 3-element call.
-    runner = Commands::FixtureRunner.new
-    runner.add(pattern: ["bin/importmap", "outdated"], stdout: "ok\n")
-    assert_raises(RuntimeError) { runner.run("bin/importmap", "outdated", "--verbose") }
-  end
-
-  def test_fixture_runner_bang_raises_command_error_on_recorded_failure
-    runner = Commands::FixtureRunner.new
-    runner.add(
-      pattern: ["bin/importmap", "pin", "lodash@4.17.21"],
-      stderr: "network error",
-      exit_code: 1
-    )
-    err = assert_raises(Commands::CommandError) { runner.run!("bin/importmap", "pin", "lodash@4.17.21") }
-    assert_equal 1, err.result.exit_code
-    assert_includes err.message, "network error"
-  end
 end