[feature] default_cli_command for config what command bundler runs when no specific command is provided

[jonbarlo]

What was the end-user or developer problem that led to this PR?

Closes#8786

The default_cli_command feature allows users to configure what command Bundler runs when no specific command is provided.

What is your fix for the problem, implemented in this PR?

Implementation Details

1. bundler/lib/bundler/settings/validator.rb

   • Added validation rule for default_cli_command
   • Ensures only valid values (install or cli_help) are accepted
   • Provides clear error messages for invalid values

2. bundler/lib/bundler/settings.rb

   • Added default_cli_command to STRING_KEYS list

3. bundler/lib/bundler/cli.rb

   • Updated version method to not show default timestamp (1980-01-02)
   • Updated cli_help method to use enhanced man-based help system

4. bundler/spec/bundler/settings_spec.rb

   • Tests for valid values, invalid values, and nil values

Key Technical Changes

Validation Rule

rule %w[default_cli_command], "default_cli_command must be either 'install' or 'cli_help'" do |key, value, settings|
  valid_values = %w[install cli_help]
  if value.nil?
    fail!(key, value, "must be one of: #{valid_values.join(", ")}")
  elsif !valid_values.include?(value.to_s)
    fail!(key, value, "must be one of: #{valid_values.join(", ")}")
  end
end

Version Display Fix

# Only show build info if it's not the default timestamp
timestamp = BuildMetadata.timestamp
unless timestamp == "1980-01-02"
  build_info = " (#{timestamp} commit #{BuildMetadata.git_commit_sha})"
end

Enhanced Help System

desc "cli_help", "Prints a summary of bundler commands", hide: true
def cli_help
  # Use the enhanced man-based help system for consistency
  help(nil)
end

Setting the Default Command

Users can configure the default CLI command using Bundler's settings system:

# Set to run 'install' by default (Bundler 3 behavior)
bundle config set default_cli_command install

# Set to run 'cli_help' by default (Bundler 4 behavior)
bundle config set default_cli_command cli_help

Valid Values

The default_cli_command setting accepts only two valid values:

• install - Runs bundle install when no command is specified (Bundler 3 behavior)
• cli_help - Displays usage help when no command is specified (Bundler 4 behavior)

Make sure the following tasks are checked

• Describe the problem / feature
• Write tests for features and bug fixes
• Write code to solve the problem
• Make sure you follow the current code style and write meaningful commit messages without tags

[deivid-rodriguez]

Please update this test to match the implementation and name it it "accepts nil values".

[deivid-rodriguez]

Also, the code in the rule checking for !value.nil? in order to not raise an error it's not even triggered by this test, because we Settings#set_local returns early if the previous value of the setting (nil in this case), matches the value passed to #set_local (nil, too).

So I'd add an extra test it "accepts nil values for unsetting an existing value of the setting" that first sets settings.set_local("default_cli_command", "install") and then checks that settings.set_local("default_cli_command", nil) does not raise an error.