Added tests for the convert_inline_callout() method.

test/test_inline_callout.rb

@@ -0,0 +1,35 @@
+require 'minitest/autorun'
+require_relative 'helper'
+
+class InlineCalloutTest < Minitest::Test
+  def test_callout_number_range
+    xml = <<~EOF.chomp.to_dita
+    ....
+    1: <1>
+    ....
+    ....
+    20: <20>
+    ....
+    ....
+    21: <21>
+    ....
+    ....
+    35: <35>
+    ....
+    ....
+    36: <36>
+    ....
+    ....
+    50: <50>
+    ....
+    EOF
+
+    # Three ranges of symbols are used to cover numbers between 1 and 50:
+    assert_xpath_equal xml, '1: &#9312;', '//pre[contains(., "1:")]/text()'
+    assert_xpath_equal xml, '20: &#9331;', '//pre[contains(., "20:")]/text()'
+    assert_xpath_equal xml, '21: &#12881;', '//pre[contains(., "21:")]/text()'
+    assert_xpath_equal xml, '35: &#12895;', '//pre[contains(., "35:")]/text()'
+    assert_xpath_equal xml, '36: &#12977;', '//pre[contains(., "36:")]/text()'
+    assert_xpath_equal xml, '50: &#12991;', '//pre[contains(., "50:")]/text()'
+  end
+end