Use the closed ASCII blank set in Redrive and enforce mandatory roundtrip case fields

Author: muhammetsafak

CHANGELOG.md

@@ -35,6 +35,8 @@ normalisation). The envelope stays frozen at `schema_version: 1`; conformance su
   (`fail` / `delete` / `release`). With `delete` it is removed silently; with `fail` the DLQ copy keeps the
   whitespace `job` and, since decode drops `urn`, loses its routable identity (ADR-0031 Consequences/Negative).
   This is what keeps cross-SDK parity (GR-5).
+  `Redrive` follows the same set: a DLQ message whose `job` is ASCII-blank is restored, while one whose `job` is only
+  Unicode whitespace is redriven like in the other SDKs (previously `Redrive` used `String.isBlank()`).
 - Conformance runners implement the v1.4.0 optional fields (`forbidden_keys.expect_preserved`,
   `roundtrip.expect_absent_after_reencode` / `apply_dead_letter` / `expect_dead_letter`) and the
   `extension_write` / `encode_reject` sections.

src/main/java/com/babelqueue/Redrive.java

@@ -246,9 +246,10 @@ public static Result redrive(Transport transport, String dlq, Options opts) thro
      */
     private static Item process(Transport transport, String dlq, Options opts, Reserved msg) throws Exception {
         // decode() never throws — a malformed/non-object body yields an empty envelope
-        // (a null job), which is not redrivable; restore it rather than drop it.
+        // (a null job), which is not redrivable; restore it rather than drop it. "Blank" is the closed
+        // ASCII set of ADR-0031 (c), not Unicode whitespace, so every SDK redrives the same messages.
         Envelope env = EnvelopeCodec.decode(msg.body());
-        if (env.job() == null || env.job().isBlank()) {
+        if (EnvelopeCodec.isBlankAscii(env.job())) {
             restore(transport, dlq, msg);
             return new Item(null, null, null, null, dlq, null, false, false);
         }

src/test/java/com/babelqueue/BehaviourConformanceTest.java

@@ -47,6 +47,10 @@ class BehaviourConformanceTest {
     @TestFactory
     Stream<DynamicTest> roundtrip() {
         return cases("roundtrip").stream().map(c -> dynamicTest(name(c), () -> {
+            // conformance/README.md (v1.4.0): "expect_attempts" and "expect_preserved" are required on every
+            // roundtrip case (the other fields are optional). A case that loses one must fail, not silently verify less.
+            assertNotNull(c.get("expect_attempts"), "roundtrip case lacks mandatory expect_attempts: " + name(c));
+            assertNotNull(c.get("expect_preserved"), "roundtrip case lacks mandatory expect_preserved: " + name(c));
             List<String> violations = roundtripViolations(c, fixture(c));
             assertTrue(violations.isEmpty(), "roundtrip violations: " + violations);
         }));

src/test/java/com/babelqueue/RedriveTest.java

@@ -183,4 +183,33 @@ void noDeadLetterFallsBackToMetaQueue() throws Exception {
         assertEquals(1, res.redriven());
         assertEquals(1, t.size("orders"));
     }
+
+    /** ADR-0031 (c): "blank" is the closed ASCII set, so an ASCII-blank job is not redrivable ... */
+    @Test
+    void asciiBlankJobIsRestoredNotRedriven() throws Exception {
+        MemoryTransport t = new MemoryTransport();
+        String body = "{\"job\":\" \\t\\n\",\"data\":{},\"meta\":{\"queue\":\"orders\"},\"attempts\":1}";
+        t.publish("dlq", body);
+
+        Redrive.Result res = Redrive.redrive(t, "dlq", Redrive.Options.all());
+
+        assertEquals(0, res.redriven());
+        assertEquals(1, res.skipped());
+        assertEquals(1, t.size("dlq"), "blank-job message must stay in the DLQ");
+        assertEquals(0, t.size("orders"));
+    }
+
+    /** ... while a job made only of Unicode whitespace (U+2003) is not blank and is redriven like any other SDK does. */
+    @Test
+    void unicodeWhitespaceJobIsRedrivenNotTreatedAsBlank() throws Exception {
+        MemoryTransport t = new MemoryTransport();
+        String body = "{\"job\":\"\\u2003\",\"data\":{},\"meta\":{\"queue\":\"orders\"},\"attempts\":1}";
+        t.publish("dlq", body);
+
+        Redrive.Result res = Redrive.redrive(t, "dlq", Redrive.Options.all());
+
+        assertEquals(1, res.redriven());
+        assertEquals(0, t.size("dlq"));
+        assertEquals(1, t.size("orders"));
+    }
 }