feat(chart): support fixed y-axis domains

src/components/core/yDomain.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, it } from 'vitest'
+
+import type { DisplayTrack } from './types'
+import { hasFixedYDomainForTrack, mergeYDomains, normalizeYDomain } from './yDomain'
+
+const track: DisplayTrack = {
+  id: 'shared-track',
+  series: [],
+  visibleSeries: [
+    {
+      id: 'channel-a',
+      name: 'A',
+      color: '#1677ff',
+      lineType: 'linear',
+      lineStyle: 'solid',
+      pointType: 'none',
+      errorBar: { visible: false, width: 1.5, capWidth: 8 },
+      points: [],
+      xDomain: [0, 1],
+      yDomain: [0, 1],
+      hasErrorPoints: false,
+    },
+  ],
+  xDomain: [0, 1],
+  yDomain: [0, 1],
+}
+
+describe('fixed Y domains', () => {
+  it('normalizes valid reversed domains', () => {
+    expect(normalizeYDomain([97, 3])).toEqual([3, 97])
+    expect(normalizeYDomain([-10, 10])).toEqual([-10, 10])
+  })
+
+  it.each([undefined, [1, 1], [Number.NaN, 1], [0, Number.POSITIVE_INFINITY]])(
+    'rejects an invalid domain: %j',
+    (domain) => {
+      expect(normalizeYDomain(domain as [number, number] | undefined)).toBeUndefined()
+    },
+  )
+
+  it('detects valid track, series, and global configuration only', () => {
+    expect(hasFixedYDomainForTrack(track, [-1, 1])).toBe(true)
+    expect(hasFixedYDomainForTrack(track, undefined, { 'shared-track': [-2, 2] })).toBe(true)
+    expect(hasFixedYDomainForTrack(track, undefined, { 'channel-a': [-3, 3] })).toBe(true)
+    expect(hasFixedYDomainForTrack(track, [0, 0], { 'channel-a': [1, 1] })).toBe(false)
+  })
+
+  it('merges configured and automatic series domains without padding', () => {
+    expect(
+      mergeYDomains([
+        [3, 97],
+        [-20, 40],
+      ]),
+    ).toEqual([-20, 97])
+  })
+})