Format tests

lib/liquid/standardfilters.rb

@@ -391,6 +391,17 @@ module Liquid
       raise Liquid::FloatDomainError, e.message
     end
 
+    # Defaults are passed as nil so systems can easily override
+    def format_number(input, options = {})
+      options = {} unless options.is_a?(Hash)
+      precision = options['precision'] || 2
+      delimiter = options['delimiter'] || " ".freeze
+      separator = options['separator'] || ".".freeze
+      return input if (prec = Utils.to_number(precision).to_i) < 0
+      whole_part, decimal_part = Kernel.format("%.#{prec}f", Utils.to_number(input)).split('.')
+      [whole_part.gsub(/(\d)(?=\d{3}+$)/, "\\1#{delimiter}"), decimal_part].compact.join(separator.to_s)
+    end
+
     def ceil(input)
       Utils.to_number(input).ceil.to_i
     rescue ::FloatDomainError => e

test/integration/standard_filter_test.rb

@@ -610,6 +610,25 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result "4", "{{ price | round }}", 'price' => NumberLikeThing.new(4.3)
   end
 
+  def test_format_number
+    assert_template_result "4.60", "{{ input | format_number }}", 'input' => 4.6
+    assert_template_result "4.30", "{{ '4.3' | format_number }}"
+    assert_template_result "4.56", "{{ input | format_number: precision: 2 }}", 'input' => 4.5612
+    assert_template_result "5", "{{ price | format_number: precision: 0 }}", 'price' => NumberLikeThing.new(4.6)
+    assert_template_result "4", "{{ price | format_number: precision: 0 }}", 'price' => NumberLikeThing.new(4.3)
+    assert_template_result "4.30", "{{ price | format_number: precision: 2 }}", 'price' => NumberLikeThing.new(4.3)
+    assert_template_result "5.0000000", "{{ price | format_number: precision: 7 }}", 'price' => 5
+    assert_template_result "50", "{{ price | format_number: precision: -1 }}", 'price' => 50
+    assert_template_result "50.00", "{{ price | format_number: precision: A }}", 'price' => 50
+    assert_template_result "50.00", "{{ price | format_number: precision: '2e' }}", 'price' => 50
+    assert_template_result "50 000 000", "{{ price | format_number: precision: 0 }}", 'price' => 50000000
+    assert_template_result "50 000 000.00", "{{ price | format_number }}", 'price' => 50000000
+    assert_template_result "50000000.00", "{{ price | format_number: precision: 2, delimiter: '', separator: '.'}}", 'price' => 50000000
+    assert_template_result "50$000$000#00", "{{ price | format_number: precision: 2, delimiter: '$', separator:'#'}}", 'price' => 50000000
+    assert_template_result "-50$000$000#00", "{{ price | format_number: precision: 2, delimiter: '$', separator: '#'}}", 'price' => -50000000
+    assert_template_result "-50 000 000.00", "{{ price | format_number: precision: A, delimiter: A, separator: A}}", 'price' => -50000000
+  end
+
   def test_ceil
     assert_template_result "5", "{{ input | ceil }}", 'input' => 4.6
     assert_template_result "5", "{{ '4.3' | ceil }}"