test: ReadingPosition serde round-trip tests for all 6 variants

crates/zx_document_core/src/progress.rs

@@ -28,3 +28,75 @@ pub enum ReadingPosition {
     },
     Unknown,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_markdown_serde() {
+        let pos = ReadingPosition::Markdown {
+            block_id: "h1".into(),
+            scroll_progress: 0.5,
+        };
+        let json = serde_json::to_string(&pos).unwrap();
+        assert!(json.contains("\"type\":\"Markdown\""));
+        let back: ReadingPosition = serde_json::from_str(&json).unwrap();
+        assert_eq!(back, pos);
+    }
+
+    #[test]
+    fn test_text_serde() {
+        let pos = ReadingPosition::Text {
+            line_number: 42,
+            scroll_progress: 0.3,
+        };
+        let json = serde_json::to_string(&pos).unwrap();
+        let back: ReadingPosition = serde_json::from_str(&json).unwrap();
+        assert_eq!(back, pos);
+    }
+
+    #[test]
+    fn test_pdf_serde() {
+        let pos = ReadingPosition::Pdf {
+            page_number: 7,
+            page_progress: 0.8,
+            overall_progress: 0.35,
+        };
+        let json = serde_json::to_string(&pos).unwrap();
+        let back: ReadingPosition = serde_json::from_str(&json).unwrap();
+        assert_eq!(back, pos);
+    }
+
+    #[test]
+    fn test_image_serde() {
+        let pos = ReadingPosition::Image {
+            zoom_scale: 1.5,
+            offset_x: 100.0,
+            offset_y: 200.0,
+        };
+        let json = serde_json::to_string(&pos).unwrap();
+        let back: ReadingPosition = serde_json::from_str(&json).unwrap();
+        assert_eq!(back, pos);
+    }
+
+    #[test]
+    fn test_epub_serde() {
+        let pos = ReadingPosition::Epub {
+            chapter_id: "ch3".into(),
+            chapter_progress: 0.6,
+            overall_progress: 0.25,
+        };
+        let json = serde_json::to_string(&pos).unwrap();
+        let back: ReadingPosition = serde_json::from_str(&json).unwrap();
+        assert_eq!(back, pos);
+    }
+
+    #[test]
+    fn test_unknown_serde() {
+        let pos = ReadingPosition::Unknown;
+        let json = serde_json::to_string(&pos).unwrap();
+        let back: ReadingPosition = serde_json::from_str(&json).unwrap();
+        assert_eq!(back, pos);
+    }
+}