test: improve reverse reference resolution handling

src/csv-loader/loader.test.ts

@@ -1166,26 +1166,49 @@ describe("parseCsv - reverse reference resolution", () => {
   });
 
   it("should handle multiple comment lines including plain comments and reverse references", () => {
-    const csv = [
-      "# id: id of user",
-      "# orders: list of related orders",
-      "# orders := ~order(user)",
-      "id,name",
-      "string,string",
-      "u01,Alice",
-      "u02,Bob",
+    const orderCsvPath = path.join(fixturesDir, "order.csv");
+    const orderContent = [
+      "id,user,total",
+      "string,string,number",
+      "o01,u01,100",
+      "o02,u01,50",
+      "o03,u02,75",
     ].join("\n");
+    fs.writeFileSync(orderCsvPath, orderContent);
 
-    const result = parseCsv(csv, {
-      emitTypes: false,
-      currentFilePath: path.join(fixturesDir, "test.csv"),
-    });
+    try {
+      const csv = [
+        "# id: id of user",
+        "# orders: list of related orders",
+        "# orders := ~order(user)",
+        "id,name",
+        "string,string",
+        "u01,Alice",
+        "u02,Bob",
+      ].join("\n");
 
-    expect(result.reverseReferences).toHaveLength(1);
-    expect(result.reverseReferences[0].fieldName).toBe("orders");
-    expect(result.data).toHaveLength(2);
-    expect(result.data[0].id).toBe("u01");
-    expect(result.data[1].id).toBe("u02");
+      const result = parseCsv(csv, {
+        emitTypes: false,
+        currentFilePath: path.join(fixturesDir, "test.csv"),
+      });
+
+      expect(result.reverseReferences).toHaveLength(1);
+      expect(result.reverseReferences[0].fieldName).toBe("orders");
+      expect(result.data).toHaveLength(2);
+      expect(result.data[0].id).toBe("u01");
+      expect(result.data[1].id).toBe("u02");
+      // User u01 (Alice) should have 2 orders
+      const aliceOrders = result.data[0].orders as Record<string, unknown>[];
+      expect(aliceOrders).toHaveLength(2);
+      expect(aliceOrders[0]).toEqual({ id: "o01", user: "u01", total: 100 });
+      expect(aliceOrders[1]).toEqual({ id: "o02", user: "u01", total: 50 });
+      // User u02 (Bob) should have 1 order
+      const bobOrders = result.data[1].orders as Record<string, unknown>[];
+      expect(bobOrders).toHaveLength(1);
+      expect(bobOrders[0].id).toBe("o03");
+    } finally {
+      fs.unlinkSync(orderCsvPath);
+    }
   });
 });
 

src/csv-loader/loader.ts

@@ -802,25 +802,10 @@ export function parseCsv(
     relax_column_count: true,
   });
 
-  if (records.length < 2) {
-    throw new Error("CSV must have at least 2 rows: headers and schemas");
-  }
-
-  const headers = records[0];
-  const schemas = records[1];
-
-  if (headers.length !== schemas.length) {
-    throw new Error(
-      `Header count (${headers.length}) does not match schema count (${schemas.length})`,
-    );
-  }
-
-  // Parse reverse reference declarations from comment lines between schema row and data rows
+  // Filter out comment lines from all records, collecting reverse reference declarations
   const reverseReferences: ReverseReferenceDeclaration[] = [];
-  const dataRows: string[][] = [];
-  for (let i = 2; i < records.length; i++) {
-    const row = records[i];
-    // Check if this is a comment line (starting with the configured comment character)
+  const filteredRecords: string[][] = [];
+  for (const row of records) {
     const firstCell = (row[0] ?? "").trim();
     if (comment && firstCell.startsWith(comment)) {
       const decl = parseReverseReferenceDeclaration(firstCell, comment);
@@ -830,9 +815,24 @@ export function parseCsv(
       // Skip comment lines (whether or not they're reverse ref declarations)
       continue;
     }
-    dataRows.push(row);
+    filteredRecords.push(row);
   }
 
+  if (filteredRecords.length < 2) {
+    throw new Error("CSV must have at least 2 rows: headers and schemas");
+  }
+
+  const headers = filteredRecords[0];
+  const schemas = filteredRecords[1];
+
+  if (headers.length !== schemas.length) {
+    throw new Error(
+      `Header count (${headers.length}) does not match schema count (${schemas.length})`,
+    );
+  }
+
+  const dataRows = filteredRecords.slice(2);
+
   // Also check schema row cells for comment-prefixed reverse reference declarations
   // (in case they appear as schema cells rather than separate rows)
   for (let col = 0; col < schemas.length; col++) {