feat: parse files in parallel at import when multiple (#2372)

cf https://github.com/umap-project/umap/pull/2363#discussion_r1882966275

umap/static/umap/js/modules/data/layer.js

@@ -526,15 +526,13 @@ export class DataLayer extends ServerStored {
   }
 
   async importFromFiles(files, type) {
-    let all = []
+    const toLoad = []
     for (const file of files) {
-      const features = await this.importFromFile(file, type)
+      toLoad.push(this.importFromFile(file, type))
-      if (features) {
-        all = all.concat(features)
-      }
     }
+    const features = await Promise.all(toLoad)
     return new Promise((resolve) => {
-      resolve(all)
+      resolve([].concat(...features))
     })
   }
 

umap/tests/fixtures/test_upload_simple_marker.json

@@ -0,0 +1,19 @@
+{
+    "crs": null,
+    "type": "FeatureCollection",
+    "features": [
+        {
+            "type": "Feature",
+            "geometry": {
+                "coordinates": [
+                    -1.09314,
+                    50.791718
+                ],
+                "type": "Point"
+            },
+            "properties": {
+                "name": "Portsmouth"
+            }
+        }
+    ]
+}

umap/tests/integration/test_import.py

@@ -9,7 +9,6 @@ from playwright.sync_api import expect
 
 from umap.models import DataLayer
 
-from ..base import mock_tiles
 from .helpers import save_and_get_json
 
 pytestmark = pytest.mark.django_db
@@ -765,3 +764,23 @@ def test_import_georss_from_textarea(tilelayer, live_server, page):
     # A layer has been created
     expect(layers).to_have_count(1)
     expect(markers).to_have_count(1)
+
+
+def test_import_from_multiple_files(live_server, page, tilelayer):
+    page.goto(f"{live_server.url}/map/new/")
+    page.get_by_title("Import data").click()
+    file_input = page.locator("input[type='file']")
+    with page.expect_file_chooser() as fc_info:
+        file_input.click()
+    file_chooser = fc_info.value
+    FIXTURES = Path(__file__).parent.parent / "fixtures"
+    paths = [
+        FIXTURES / "test_upload_data.json",
+        FIXTURES / "test_upload_simple_marker.json",
+    ]
+    file_chooser.set_files(paths)
+    markers = page.locator(".leaflet-marker-icon")
+    expect(markers).to_have_count(0)
+    page.get_by_role("button", name="Import data", exact=True).click()
+    # Two in one file, one in the other
+    expect(markers).to_have_count(3)