Add new baseline use case provided by forum user and fix test with form

The input "some text" was hard-coded into the form.
Also, take the chance to use the parameterized values directly in the form's contents to avoid having to answer questions and to make the calculate expression simpler, since we can assume that the values will be always there.

src/test/java/org/javarosa/xpath/expr/DigestTest.java

@@ -73,7 +73,9 @@ public static Iterable<Object[]> data() {
  {"SHA-1", SHA1, "some text", BASE64, "N6pjx3OY2VRHMmLhoAV8HmMu2nc="},
  {"SHA-256", SHA256, "some text", BASE64, "uU9vElx546X/qoJvWEwQ1SraZp5nYgUbgmtVd20FrtI="},
  {"SHA-384", SHA384, "some text", BASE64, "zJTsPphzwLmnJIZEKVj2cQZ833e5QnQW0DFEDMYgQeLuE0RJhEfsDO2fcENGG9Hz"},
- {"SHA-512", SHA512, "some text", BASE64, "4nMrrtyj6sFAeChjfeHbynAsP8ns4Wz1Nt241hOc2F3+dGS4I1spgm9gjM9KxkPimxnGN4WKPYcQpZER30LdtQ=="}
+ {"SHA-512", SHA512, "some text", BASE64, "4nMrrtyj6sFAeChjfeHbynAsP8ns4Wz1Nt241hOc2F3+dGS4I1spgm9gjM9KxkPimxnGN4WKPYcQpZER30LdtQ=="},
+
+ {"MD5 HEX of empty string (baseline from forum feedback)", MD5, "", HEX, "d41d8cd98f00b204e9800998ecf8427e"}
  });
  }
 
@@ -89,15 +91,15 @@ public void digestFunction_acceptsDynamicParameters() throws IOException {
  title("Digest form"),
  model(
  mainInstance(t("data id=\"digest\"",
- t("my-text"),
- t("my-algorithm"),
- t("my-encoding"),
+ t("my-text", input),
+ t("my-algorithm", algorithm.toString()),
+ t("my-encoding", encoding.toString()),
  t("my-digest")
  )),
  bind("/data/my-text").type("string"),
  bind("/data/my-algorithm").type("string"),
  bind("/data/my-encoding").type("string"),
- bind("/data/my-digest").type("string").calculate("if(/data/my-algorithm != '' and /data/my-encoding != '', digest(/data/my-text, /data/my-algorithm, /data/my-encoding), '')")
+ bind("/data/my-digest").type("string").calculate("digest(/data/my-text, /data/my-algorithm, /data/my-encoding)")
  )
  ),
  body(
@@ -107,9 +109,6 @@ public void digestFunction_acceptsDynamicParameters() throws IOException {
  ))
  );
 
- scenario.answer("/data/my-text", "some text");
- scenario.answer("/data/my-algorithm", algorithm.toString());
- scenario.answer("/data/my-encoding", encoding.toString());
  assertThat(scenario.answerOf("/data/my-digest"), is(stringAnswer(expectedOutput)));
  }
 }