fix: don't default null replicas/readyReplicas in Readiness checks

util/src/main/java/io/kubernetes/client/util/Readiness.java

@@ -206,13 +206,15 @@ public static boolean isReplicaSetReady(V1ReplicaSet replicaSet) {
         Integer readyReplicas = status.getReadyReplicas();
 
         if (replicas == null) {
-            replicas = 1;
-        }
-        if (readyReplicas == null) {
-            readyReplicas = 0;
+            return false;
         }
+        // readyReplicas is `omitempty` in the real API (a plain int, not a pointer), so the
+        // API server omits it from the JSON whenever it's genuinely 0 - not just when it
+        // hasn't been reported yet. A null here means "zero", matching client-go's own
+        // comparison (*(rs.Spec.Replicas) == rs.Status.ReadyReplicas), not "unknown".
+        int effectiveReadyReplicas = readyReplicas == null ? 0 : readyReplicas;
 
-        return replicas.equals(readyReplicas);
+        return replicas.equals(effectiveReadyReplicas);
     }
 
     /**
@@ -380,13 +382,15 @@ public static boolean isReplicationControllerReady(V1ReplicationController repli
         Integer readyReplicas = status.getReadyReplicas();
 
         if (replicas == null) {
-            replicas = 1;
-        }
-        if (readyReplicas == null) {
-            readyReplicas = 0;
+            return false;
         }
+        // readyReplicas is `omitempty` in the real API (a plain int, not a pointer), so the
+        // API server omits it from the JSON whenever it's genuinely 0 - not just when it
+        // hasn't been reported yet. A null here means "zero", matching client-go's own
+        // semantics, not "unknown".
+        int effectiveReadyReplicas = readyReplicas == null ? 0 : readyReplicas;
 
-        return replicas.equals(readyReplicas);
+        return replicas.equals(effectiveReadyReplicas);
     }
 
     /**

util/src/test/java/io/kubernetes/client/util/ReadinessTest.java

@@ -222,6 +222,41 @@ void isReplicaSetReady_notAllReplicasReady_returnsFalse() {
         assertThat(Readiness.isReplicaSetReady(replicaSet)).isFalse();
     }
 
+    @Test
+    void isReplicaSetReady_nullSpecReplicas_returnsFalse() {
+        // Regression test: a null spec.replicas must not be silently treated as "1".
+        V1ReplicaSet replicaSet = new V1ReplicaSet()
+                .metadata(new V1ObjectMeta().name("test"))
+                .spec(new V1ReplicaSetSpec())
+                .status(new V1ReplicaSetStatus().readyReplicas(1));
+        assertThat(Readiness.isReplicaSetReady(replicaSet)).isFalse();
+    }
+
+    @Test
+    void isReplicaSetReady_zeroReplicasWithNullReadyReplicas_returnsTrue() {
+        // readyReplicas is `omitempty` on a plain int in the real API, so the API server
+        // omits it from the JSON whenever it's genuinely 0 - not just when it hasn't been
+        // reported yet. A null readyReplicas here should be treated as 0, matching
+        // client-go's own WaitForReadyReplicaSet check (spec.replicas == status.readyReplicas),
+        // which considers a zero-replica ReplicaSet ready once its status is all-zero.
+        V1ReplicaSet replicaSet = new V1ReplicaSet()
+                .metadata(new V1ObjectMeta().name("test"))
+                .spec(new V1ReplicaSetSpec().replicas(0))
+                .status(new V1ReplicaSetStatus());
+        assertThat(Readiness.isReplicaSetReady(replicaSet)).isTrue();
+    }
+
+    @Test
+    void isReplicaSetReady_nonZeroReplicasWithNullReadyReplicas_returnsFalse() {
+        // A null readyReplicas is treated as 0 (see above), so a non-zero desired replica
+        // count still correctly reports not-ready when readyReplicas is null.
+        V1ReplicaSet replicaSet = new V1ReplicaSet()
+                .metadata(new V1ObjectMeta().name("test"))
+                .spec(new V1ReplicaSetSpec().replicas(3))
+                .status(new V1ReplicaSetStatus());
+        assertThat(Readiness.isReplicaSetReady(replicaSet)).isFalse();
+    }
+
     // ========== DaemonSet Tests ==========
 
     @Test
@@ -337,6 +372,39 @@ void isReplicationControllerReady_allReplicasReady_returnsTrue() {
         assertThat(Readiness.isReplicationControllerReady(rc)).isTrue();
     }
 
+    @Test
+    void isReplicationControllerReady_nullSpecReplicas_returnsFalse() {
+        // Regression test: a null spec.replicas must not be silently treated as "1".
+        V1ReplicationController rc = new V1ReplicationController()
+                .metadata(new V1ObjectMeta().name("test"))
+                .spec(new io.kubernetes.client.openapi.models.V1ReplicationControllerSpec())
+                .status(new V1ReplicationControllerStatus().readyReplicas(1));
+        assertThat(Readiness.isReplicationControllerReady(rc)).isFalse();
+    }
+
+    @Test
+    void isReplicationControllerReady_zeroReplicasWithNullReadyReplicas_returnsTrue() {
+        // readyReplicas is `omitempty` on a plain int in the real API, so it's omitted from
+        // the JSON whenever it's genuinely 0, not just when unreported. A null readyReplicas
+        // should be treated as 0, matching client-go's semantics for a zero-replica resource.
+        V1ReplicationController rc = new V1ReplicationController()
+                .metadata(new V1ObjectMeta().name("test"))
+                .spec(new io.kubernetes.client.openapi.models.V1ReplicationControllerSpec().replicas(0))
+                .status(new V1ReplicationControllerStatus());
+        assertThat(Readiness.isReplicationControllerReady(rc)).isTrue();
+    }
+
+    @Test
+    void isReplicationControllerReady_nonZeroReplicasWithNullReadyReplicas_returnsFalse() {
+        // A null readyReplicas is treated as 0 (see above), so a non-zero desired replica
+        // count still correctly reports not-ready when readyReplicas is null.
+        V1ReplicationController rc = new V1ReplicationController()
+                .metadata(new V1ObjectMeta().name("test"))
+                .spec(new io.kubernetes.client.openapi.models.V1ReplicationControllerSpec().replicas(3))
+                .status(new V1ReplicationControllerStatus());
+        assertThat(Readiness.isReplicationControllerReady(rc)).isFalse();
+    }
+
     // ========== PersistentVolumeClaim Tests ==========
 
     @Test
@@ -447,4 +515,4 @@ void isReady_delegatesToCorrectMethod_forJob() {
                                         .status("True"))));
         assertThat(Readiness.isReady(job)).isTrue();
     }
-}
+}