test(jimeng): cover body assembly and poll parameters

Round out request-body validation and pin the polling parameters:
- all five allowed aspect ratios and both frame counts build
- prompt + image_urls together both land in the video body
- whitespace-only prompt is dropped but an image still satisfies one-of
- optional video fields are omitted when absent
- default poll interval/timeout values (image 2s/120s, video 8s/600s)

src/services/jimeng/mod.rs

@@ -384,4 +384,101 @@ mod tests {
             Err(JimengError::Disabled)
         ));
     }
+
+    #[test]
+    fn video_body_accepts_all_allowed_aspect_ratios() {
+        for ratio in ALLOWED_ASPECT_RATIOS {
+            let req = VideoRequest {
+                prompt: Some("x".into()),
+                image_urls: vec![],
+                frames: 121,
+                aspect_ratio: Some(ratio.to_string()),
+                seed: None,
+            };
+            let body = build_video_body(&req)
+                .unwrap_or_else(|e| panic!("ratio {ratio} should be allowed: {e:?}"));
+            assert_eq!(body["aspect_ratio"], ratio);
+        }
+    }
+
+    #[test]
+    fn video_body_accepts_both_frame_counts() {
+        for frames in ALLOWED_FRAMES {
+            let req = VideoRequest {
+                prompt: Some("x".into()),
+                image_urls: vec![],
+                frames,
+                aspect_ratio: None,
+                seed: None,
+            };
+            let body = build_video_body(&req)
+                .unwrap_or_else(|e| panic!("frames {frames} should be allowed: {e:?}"));
+            assert_eq!(body["frames"], frames);
+        }
+    }
+
+    #[test]
+    fn video_body_includes_prompt_and_image_together() {
+        // Both inputs supplied (image-to-video with a guiding prompt): both end
+        // up in the body.
+        let req = VideoRequest {
+            prompt: Some("a dragon".into()),
+            image_urls: vec!["https://x/a.jpg".into(), "https://x/b.jpg".into()],
+            frames: 241,
+            aspect_ratio: Some("9:16".into()),
+            seed: Some(42),
+        };
+        let body = build_video_body(&req).unwrap();
+        assert_eq!(body["prompt"], "a dragon");
+        assert_eq!(body["image_urls"][1], "https://x/b.jpg");
+        assert_eq!(body["frames"], 241);
+        assert_eq!(body["seed"], 42);
+    }
+
+    #[test]
+    fn video_body_drops_whitespace_prompt_but_keeps_image() {
+        // A whitespace-only prompt is not a real prompt: it must not be written
+        // to the body, yet the image alone satisfies the "one of" requirement.
+        let req = VideoRequest {
+            prompt: Some("   ".into()),
+            image_urls: vec!["https://x/a.jpg".into()],
+            frames: 121,
+            aspect_ratio: None,
+            seed: None,
+        };
+        let body = build_video_body(&req).unwrap();
+        let obj = body.as_object().unwrap();
+        assert!(!obj.contains_key("prompt"), "blank prompt must be omitted");
+        assert_eq!(body["image_urls"][0], "https://x/a.jpg");
+    }
+
+    #[test]
+    fn video_body_omits_absent_optional_fields() {
+        let req = VideoRequest {
+            prompt: Some("x".into()),
+            image_urls: vec![],
+            frames: 121,
+            aspect_ratio: None,
+            seed: None,
+        };
+        let body = build_video_body(&req).unwrap();
+        let obj = body.as_object().unwrap();
+        assert!(!obj.contains_key("aspect_ratio"));
+        assert!(!obj.contains_key("seed"));
+        assert!(!obj.contains_key("image_urls"));
+    }
+
+    #[test]
+    fn default_poll_parameters_differ_image_vs_video() {
+        // The submit→poll state machine reads interval/timeout from config; lock
+        // the shipped defaults so a regression in JimengConfig is caught here.
+        let cfg = JimengConfig::default();
+        assert_eq!(cfg.image_poll_interval_secs, 2);
+        assert_eq!(cfg.image_timeout_secs, 120);
+        assert_eq!(cfg.video_poll_interval_secs, 8);
+        assert_eq!(cfg.video_timeout_secs, 600);
+        // Video is the longer-running capability: bigger interval and timeout.
+        assert!(cfg.video_poll_interval_secs > cfg.image_poll_interval_secs);
+        assert!(cfg.video_timeout_secs > cfg.image_timeout_secs);
+    }
 }