allow true for thousands separator

lib/money/money/formatter.rb

@@ -124,11 +124,14 @@ class Formatter
     #  the currency should be delimited by the specified character or ','
     #
     # @example
-    #   # If false is specified, no thousands_separator is used.
+    #   # If a falsey value is specified, no thousands_separator is used.
     #   Money.new(100000, "USD").format(thousands_separator: false) #=> "1000.00"
     #   Money.new(100000, "USD").format(thousands_separator: nil)   #=> "1000.00"
     #   Money.new(100000, "USD").format(thousands_separator: "")    #=> "1000.00"
     #
+    #   # If true is specified, the locale or default thousands_separator is used.
+    #   Money.new(100000, "USD").format(thousands_separator: true) #=> "1,000.00"
+    #
     #   # If a string is specified, it's value is used.
     #   Money.new(100000, "USD").format(thousands_separator: ".") #=> "$1.000.00"
     #
@@ -241,7 +244,13 @@ def to_s
     end
 
     def thousands_separator
-      lookup :thousands_separator
+      val = lookup :thousands_separator
+
+      if val == true
+        val = (Money.locale_backend && Money.locale_backend.lookup(:thousands_separator, currency)) || DEFAULTS[key]
+      end
+
+      val
     end
 
     def decimal_mark

spec/money/formatting_spec.rb

@@ -447,6 +447,7 @@
 
     describe ":thousands_separator option" do
       specify "(thousands_separator: a thousands_separator string) works as documented" do
+        expect(Money.us_dollar(100000).format(thousands_separator: ".")).to eq "$1.000.00"
         expect(Money.us_dollar(100000).format(thousands_separator: ".")).to eq "$1.000.00"
         expect(Money.us_dollar(200000).format(thousands_separator: "")).to eq "$2000.00"
       end
@@ -456,6 +457,10 @@
         expect(Money.us_dollar(200000).format(thousands_separator: nil)).to eq "$2000.00"
       end
 
+      specify "(thousands_separator: true) works as documented" do
+        expect(Money.us_dollar(100000).format(thousands_separator: true)).to eq "$1,000.00"
+      end
+
       specify "(delimiter: a delimiter string) works as documented" do
         expect(Money.us_dollar(100000).format(delimiter: ".")).to eq "$1.000.00"
         expect(Money.us_dollar(200000).format(delimiter: "")).to eq "$2000.00"
@@ -466,6 +471,10 @@
         expect(Money.us_dollar(200000).format(delimiter: nil)).to eq "$2000.00"
       end
 
+      specify "(delimiter: true) works as documented" do
+        expect(Money.us_dollar(100000).format(delimiter: true)).to eq "$1,000.00"
+      end
+
       it "defaults to ',' if currency isn't recognized" do
         expect(Money.new(100000, "ZWD").format).to eq "$1,000.00"
       end