add an example from discussion 155 on the mustache spec

compiler/src/test/java/com/github/mustachejava/SpecDisc155Test.java

@@ -0,0 +1,64 @@
+package com.github.mustachejava;
+
+import com.github.mustachejavabenchmarks.NullWriter;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Function;
+
+import static org.junit.Assert.assertEquals;
+
+public class SpecDisc155Test {
+
+    static class Friend {
+        String name = "Sam";
+    }
+
+    static class I18N {
+        String translationKey;
+        Function<String, String> key = content -> {
+            translationKey = content;
+            return "";
+        };
+        String defaultText;
+        TemplateFunction t = content -> {
+            defaultText = content;
+            return "";
+        };
+
+        Map<String, String> translations;
+
+        {
+            translations = new HashMap<>();
+            translations.put("goodmorning", "좋은 아침이에요 {{name}}");
+        }
+
+        MustacheFactory mf = new DefaultMustacheFactory();
+
+        TemplateFunction i18n = content -> {
+            try {
+                mf.compile(new StringReader(content), "i18n").execute(new NullWriter(), this).flush();
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+            if (translations.containsKey(translationKey)) {
+                return translations.get(translationKey);
+            } else {
+                return defaultText;
+            }
+        };
+    }
+
+    @Test
+    public void testDisc155() throws IOException {
+        MustacheFactory mf = new DefaultMustacheFactory();
+        Mustache m = mf.compile(new StringReader("{{#friend}}{{#i18n}}{{#key}}goodmorning{{/key}}{{#t}}Good morning, {{name}}{{/t}}{{/i18n}}{{/friend}}"), "test");
+        StringWriter sw = new StringWriter();
+        m.execute(sw, new Object[] {new I18N(), new Object() { public Friend friend = new Friend();}}).flush();
+        assertEquals("좋은 아침이에요 Sam", sw.toString());
+    }
+}