test(import): add a synthetic export.xml fixture for the origin marker

The fixture is invented, in the shape Apple's DTD documents, and says so in its
header and its file name. It shows the parser reads a file laid out like an
export; it cannot show that Apple writes a custom metadata key verbatim.

tests/integration/apple-health-import-own-samples.test.ts

@@ -116,6 +116,35 @@ describe("a record HealthLog wrote itself (the origin marker)", () => {
   });
 });
 
+describe("the synthetic export fixture", () => {
+  // `export-own-origin.synthetic.xml` is invented, in the shape Apple's DTD
+  // documents. It shows the parser reads a file laid out like an export; it
+  // cannot show that Apple writes a custom metadata key verbatim.
+  it("leaves out the two marked records and imports the other three", async () => {
+    const user = await prisma.user.create({
+      data: { username: "own-fixture", email: "fx@example.test", role: "USER" },
+    });
+    const result = await streamParseExportXml({
+      xmlPath: join(
+        process.cwd(),
+        "tests/fixtures/apple-health/export-own-origin.synthetic.xml",
+      ),
+      userId: user.id,
+      userTimezone: "Europe/Berlin",
+      prisma,
+    });
+    const rows = await prisma.measurement.findMany({
+      where: { userId: user.id, type: "WEIGHT", source: "APPLE_HEALTH" },
+      orderBy: { measuredAt: "asc" },
+    });
+    expect(rows.map((r) => r.value)).toEqual([80.2, 80.4, 80.5]);
+    expect(result.writtenByHealthLog).toEqual({
+      byMarker: 2,
+      matchedManual: 0,
+    });
+  });
+});
+
 describe("a manual entry mirrored before the marker existed", () => {
   async function runAgainst(
     manual: { value: number; at: string; source?: "MANUAL" | "WITHINGS" },