Add negative label filtering for cards

client/src/utils/filter-card-labels.js

@@ -0,0 +1,20 @@
+const getLabelIds = (card) =>
+  card.labels.toRefArray
+    ? card.labels.toRefArray().map((label) => label.id)
+    : card.labels.map((label) => label.id);
+
+const filterCardLabels = (cards, includedLabelIds, excludedLabelIds) =>
+  cards.filter((card) => {
+    const labelIds = getLabelIds(card);
+
+    if (
+      includedLabelIds.length > 0 &&
+      !labelIds.some((labelId) => includedLabelIds.includes(labelId))
+    ) {
+      return false;
+    }
+
+    return !labelIds.some((labelId) => excludedLabelIds.includes(labelId));
+  });
+
+export default filterCardLabels;

client/src/utils/filter-card-labels.test.js

@@ -0,0 +1,34 @@
+import filterCardLabels from './filter-card-labels';
+
+const makeCard = (id, labelIds) => ({
+  id,
+  labels: labelIds.map((labelId) => ({ id: labelId })),
+});
+
+describe('filterCardLabels', () => {
+  it('keeps cards that have any included label', () => {
+    const cards = [makeCard('card-1', ['frontend']), makeCard('card-2', ['backend'])];
+
+    expect(filterCardLabels(cards, ['frontend'], [])).toEqual([cards[0]]);
+  });
+
+  it('keeps cards that have none of the excluded labels, including unlabeled cards', () => {
+    const cards = [
+      makeCard('card-1', ['frontend']),
+      makeCard('card-2', ['backend']),
+      makeCard('card-3', []),
+    ];
+
+    expect(filterCardLabels(cards, [], ['frontend'])).toEqual([cards[1], cards[2]]);
+  });
+
+  it('combines included and excluded labels with AND semantics', () => {
+    const cards = [
+      makeCard('card-1', ['frontend', 'blocked']),
+      makeCard('card-2', ['frontend']),
+      makeCard('card-3', ['backend']),
+    ];
+
+    expect(filterCardLabels(cards, ['frontend'], ['blocked'])).toEqual([cards[1]]);
+  });
+});