### Question:
HttpHeaderTransport { public String render(Map<String, String> context) { final StringBuilder sb = new StringBuilder(128); for (Iterator<Map.Entry<String, String>> iterator = context.entrySet().iterator(); iterator.hasNext(); ) { Map.Entry<String, String> entry = iterator.next(); try { final String key = URLEncoder.encode(entry.getKey().trim(), ENCODING_CHARSET); final String value = URLEncoder.encode(entry.getValue().trim(), ENCODING_CHARSET); sb.append(key).append('=').append(value); if (iterator.hasNext()) { sb.append(','); } } catch (UnsupportedEncodingException e) { LOGGER.error("Charset not found", e); } } return sb.toString(); }  Map<String, String> parse(List<String> serializedElements); String render(Map<String, String> context); static final String ENCODING_CHARSET; }### Answer:
@Test public void renderKeyValueWithEqualSignAndConcatWithComma() { final Map<String, String> context = new HashMap<>(); context.put("key1", "value1"); context.put("key2", "value2"); assertThat(UNIT.render(context), anyOf(is("key1=value1,key2=value2"), is("key2=value2,key1=value1"))); }
@Test public void trimValuesBeforeConcat() { final Map<String, String> context = new HashMap<>(); context.put(" key1 ", " value1 "); context.put(" key2 ", " value2 "); System.out.println(UNIT.render(context)); assertThat(UNIT.render(context), anyOf(is("key1=value1,key2=value2"), is("key2=value2,key1=value1"))); }
@Test public void renderEmptyMapResultsIntoEmptyString() { assertThat(UNIT.render(Collections.<String, String>emptyMap()), is("")); }
@Test public void specialCharsShouldGetEscapedToNonUnsafeCharacters() { final Map<String, String> context = new HashMap<>(); context.put("!\"§$%&@/( )=?", "^°+*'#-.,;:_<> ´´``"); context.put("ö üäß", "Ö ÜÄß€"); final String headerString = UNIT.render(context); assertThat(headerString, not(anyOf(containsString("\""), containsString("\\")))); }
@Test public void specialCharsShouldGetEscapedToNotUsedSeperatorCharacters() { final Map<String, String> context = new HashMap<>(); context.put("!\"§$%&@/()=? ", "^°+*'# .,;:_<>´´``"); context.put("öü äß", "ÖÜ Äß€"); final String headerString = UNIT.render(context); assertThat(headerString, not(anyOf(containsString("("), containsString(")")))); assertThat(headerString, not(anyOf(containsString("<"), containsString(">")))); assertThat(headerString, not(anyOf(containsString("{"), containsString("}")))); assertThat(headerString, not(anyOf(containsString("["), containsString("]")))); assertThat(headerString, not(anyOf(containsString("/"), containsString("\\")))); assertThat(headerString, not(anyOf(containsString(" "), containsString("\t")))); assertThat(headerString, not(anyOf(containsString("?"), containsString(":")))); assertThat(headerString, not(anyOf(containsString(";"), containsString("@")))); }
@Test public void specialCharsShouldGetEscapedAndUseOnlyCommaAndEqualsSignForConcat() { final Map<String, String> context = new HashMap<>(); context.put("!\"§$%&@/()=? ", "^°+*'# .,;:_<>´´``"); context.put("öü äß", "ÖÜ Äß€"); final String headerString = UNIT.render(context); assertThat(countChars(headerString, '='), is(2)); assertThat(countChars(headerString, ','), is(1)); }