Merge pull request #23064 from andrew/command-did-you-mean

Suggest commands for typos

Author: MikeMcQuaid

Library/Homebrew/brew.rb

@@ -143,7 +143,7 @@
     ENV["HOMEBREW_LIBRARY_PATH"] = HOMEBREW_LIBRARY_PATH.to_s
     exec external_cmd_path.to_s, *ARGV
   else
-    raise UsageError, "Unknown command: brew #{cmd}"
+    raise UsageError, "Unknown command: brew #{cmd}#{Commands.suggestion_message(cmd)}"
   end
 rescue UsageError => e
   require "help"

Library/Homebrew/commands.rb

@@ -137,6 +137,17 @@ def self.commands(external: true, aliases: false)
     cmds.sort
   end
 
+  sig { params(cmd: String).returns(String) }
+  def self.suggestion_message(cmd)
+    require "did_you_mean"
+
+    suggestions = DidYouMean::SpellChecker.new(dictionary: commands(external: false, aliases: true)).correct(cmd)
+    suggestions = DidYouMean::SpellChecker.new(dictionary: commands(aliases: true)).correct(cmd) if suggestions.empty?
+    return "" if suggestions.empty?
+
+    "\nDid you mean #{suggestions.to_sentence(two_words_connector: " or ", last_word_connector: " or ")}?"
+  end
+
   # An array of all tap cmd directory {Pathname}s.
   sig { returns(T::Array[Pathname]) }
   def self.tap_cmd_directories

Library/Homebrew/test/commands_spec.rb

@@ -86,6 +86,32 @@
     end
   end
 
+  describe "::suggestion_message" do
+    let(:internal_commands) { %w[doctor up upgrade] }
+    let(:all_commands) { %w[doctor external-command up upgrade] }
+
+    before do
+      allow(described_class).to receive(:commands).with(external: false, aliases: true).and_return(internal_commands)
+      allow(described_class).to receive(:commands).with(aliases: true).and_return(all_commands)
+    end
+
+    it "suggests a command for a typo" do
+      expect(described_class.suggestion_message("upgrde")).to eq("\nDid you mean upgrade?")
+    end
+
+    it "suggests a command alias for a typo" do
+      expect(described_class.suggestion_message("upp")).to eq("\nDid you mean up?")
+    end
+
+    it "falls back to external command suggestions" do
+      expect(described_class.suggestion_message("external-comand")).to eq("\nDid you mean external-command?")
+    end
+
+    it "does not suggest a command without a close match" do
+      expect(described_class.suggestion_message("zzzzzz")).to be_empty
+    end
+  end
+
   describe "::rebuild_internal_commands_completion_list" do
     it "omits internal command aliases" do
       mktmpdir do |repository|