Introduce plugin/disable_ternary

README.md

@@ -658,6 +658,7 @@ To register plugins, define a file somewhere in your load path named `syntax_tre
 
 * `plugin/single_quotes` - This will change all of your string literals to use single quotes instead of the default double quotes.
 * `plugin/trailing_comma` - This will put trailing commas into multiline array literals, hash literals, and method calls that can support trailing commas.
+* `plugin/disable_ternary` - This will prevent the automatic conversion of `if ... else` to ternary expressions.
 
 If you're using Syntax Tree as a library, you can require those files directly or manually pass those options to the formatter initializer through the `SyntaxTree::Formatter::Options` class.
 

lib/syntax_tree/formatter.rb

@@ -21,11 +21,15 @@ def initialize(version)
     # that folks have become entrenched in their ways, we decided to provide a
     # small amount of configurability.
     class Options
-      attr_reader :quote, :trailing_comma, :target_ruby_version
+      attr_reader :quote,
+                  :trailing_comma,
+                  :disable_ternary,
+                  :target_ruby_version
 
       def initialize(
         quote: :default,
         trailing_comma: :default,
+        disable_ternary: :default,
         target_ruby_version: :default
       )
         @quote =
@@ -50,6 +54,17 @@ def initialize(
             trailing_comma
           end
 
+        @disable_ternary =
+          if disable_ternary == :default
+            # We ship with a disable ternary plugin that will define this
+            # constant. That constant is responsible for determining the default
+            # disable ternary value. If it's defined, then we default to true.
+            # Otherwise we default to false.
+            defined?(DISABLE_TERNARY)
+          else
+            disable_ternary
+          end
+
         @target_ruby_version =
           if target_ruby_version == :default
             # The default target Ruby version is the current version of Ruby.
@@ -69,8 +84,9 @@ def initialize(
 
     # These options are overridden in plugins to we need to make sure they are
     # available here.
-    attr_reader :quote, :trailing_comma, :target_ruby_version
+    attr_reader :quote, :trailing_comma, :disable_ternary, :target_ruby_version
     alias trailing_comma? trailing_comma
+    alias disable_ternary? disable_ternary
 
     def initialize(source, *args, options: Options.new)
       super(*args)
@@ -81,6 +97,7 @@ def initialize(source, *args, options: Options.new)
       # Memoizing these values to make access faster.
       @quote = options.quote
       @trailing_comma = options.trailing_comma
+      @disable_ternary = options.disable_ternary
       @target_ruby_version = options.target_ruby_version
     end
 

lib/syntax_tree/node.rb

@@ -6154,6 +6154,7 @@ module Ternaryable
     class << self
       def call(q, node)
         return false if ENV["STREE_FAST_FORMAT"]
+        return false if q.disable_ternary?
 
         # If this is a conditional inside of a parentheses as the only content,
         # then we don't want to transform it into a ternary. Presumably the user

lib/syntax_tree/plugin/disable_ternary.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module SyntaxTree
+  class Formatter
+    DISABLE_TERNARY = true
+  end
+end

test/plugin/disable_ternary_test.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module SyntaxTree
+  class DisableTernaryTest < Minitest::Test
+    def test_short_if_else_unchanged
+      assert_format(<<~RUBY)
+        if true
+          1
+        else
+          2
+        end
+      RUBY
+    end
+
+    def test_short_ternary_unchanged
+      assert_format("true ? 1 : 2\n")
+    end
+
+    private
+
+    def assert_format(expected, source = expected)
+      options = Formatter::Options.new(disable_ternary: true)
+      formatter = Formatter.new(source, [], options: options)
+      SyntaxTree.parse(source).format(formatter)
+
+      formatter.flush
+      assert_equal(expected, formatter.output.join)
+    end
+  end
+end