Add Chart Builder: no-JSON Vega-Lite composer from a dataset (M4)

src/app/stores/ChartBuilderStore.test.ts

@@ -0,0 +1,104 @@
+import { beforeEach, describe, expect, test } from 'vitest';
+import { createDataset } from '@core/dataset';
+import { useChartBuilderStore } from './ChartBuilderStore';
+import { useDatasetStore } from './DatasetStore';
+import { useSnippetStore } from './SnippetStore';
+
+const cb = () => useChartBuilderStore.getState();
+const T = new Date('2026-06-01T00:00:00Z');
+
+/** Seed a dataset directly into the store and return its id. */
+function seedDataset(name: string, data: unknown): number {
+  const ds = createDataset({ name, data, format: 'json', source: 'inline', now: T });
+  useDatasetStore.getState().add(ds);
+  return ds.id;
+}
+
+beforeEach(() => {
+  cb().reset();
+  useDatasetStore.getState().reset();
+  useSnippetStore.getState().reset();
+});
+
+describe('init', () => {
+  test('pre-populates a smart default config from the dataset columns', () => {
+    const id = seedDataset('Traffic', [
+      { day: '2026-01-01', visits: 10 },
+      { day: '2026-01-02', visits: 20 },
+    ]);
+    cb().init(id);
+
+    expect(cb().datasetId).toBe(id);
+    expect(cb().config.datasetName).toBe('Traffic');
+    // date × number → a Line time series, first col on X, second on Y.
+    expect(cb().config.mark).toBe('line');
+    expect(cb().config.encodings.x).toEqual({ field: 'day', type: 'temporal' });
+    expect(cb().config.encodings.y).toEqual({ field: 'visits', type: 'quantitative' });
+  });
+
+  test('lands empty when no dataset is found', () => {
+    cb().init(999);
+    expect(cb().datasetId).toBeNull();
+    expect(cb().config.encodings).toEqual({});
+  });
+});
+
+describe('channel editing', () => {
+  test('mapping a column seeds a channel-appropriate type (Size stays a measure)', () => {
+    const id = seedDataset('Mixed', [{ name: 'A', value: 5 }]);
+    cb().init(id);
+    // A numeric column on Size → Quantitative (allowed); a category cannot be chosen
+    // for Size in the UI, and the store keeps the type valid for the channel.
+    cb().setChannelColumn('size', 'value');
+    expect(cb().config.encodings.size).toEqual({ field: 'value', type: 'quantitative' });
+  });
+
+  test('swapXY flips the two axis mappings', () => {
+    const id = seedDataset('XY', [{ a: 'x', b: 1 }]);
+    cb().init(id);
+    const x0 = cb().config.encodings.x;
+    const y0 = cb().config.encodings.y;
+    cb().swapXY();
+    expect(cb().config.encodings.x).toEqual(y0);
+    expect(cb().config.encodings.y).toEqual(x0);
+  });
+
+  test('clearing a channel to None removes it from the config', () => {
+    const id = seedDataset('XY', [{ a: 'x', b: 1 }]);
+    cb().init(id);
+    cb().setChannelColumn('x', null);
+    expect(cb().config.encodings.x).toBeNull();
+  });
+});
+
+describe('createSnippet', () => {
+  test('builds a linked snippet, activates it, and resets the builder', () => {
+    const id = seedDataset('Sales', [
+      { region: 'N', revenue: 100 },
+      { region: 'S', revenue: 80 },
+    ]);
+    cb().init(id);
+
+    expect(cb().createSnippet(T)).toBe(true);
+
+    const snippets = useSnippetStore.getState().snippets;
+    expect(snippets).toHaveLength(1);
+    const made = snippets[0];
+    // Linked to its dataset by name (§09F), and the spec references it.
+    expect(made.datasetRefs).toEqual(['Sales']);
+    expect(made.spec).toContain('"name": "Sales"');
+    expect(made.meta.createdWith).toBe('chart-builder');
+    expect(useSnippetStore.getState().activeSnippetId).toBe(made.id);
+    // Builder state is reset for a fresh next open.
+    expect(cb().datasetId).toBeNull();
+  });
+
+  test('refuses to create when no channel is mapped', () => {
+    const id = seedDataset('Empty', [{ a: 1 }]);
+    cb().init(id);
+    cb().setChannelColumn('x', null);
+    cb().setChannelColumn('y', null);
+    expect(cb().createSnippet(T)).toBe(false);
+    expect(useSnippetStore.getState().snippets).toHaveLength(0);
+  });
+});