test: add capacitive touch slider snapshot test with polygon smtpads

tests/components/normal-components/capacitive-touch-slider.test.tsx

@@ -0,0 +1,104 @@
+import { test, expect } from "bun:test"
+import { getTestFixture } from "tests/fixtures/get-test-fixture"
+
+/**
+ * Capacitive Touch Slider using polygon smtpads with coveredWithSolderMask
+ *
+ * A capacitive touch slider consists of multiple polygon-shaped SMT pads
+ * covered with solder mask. The solder mask acts as the dielectric, and the
+ * copper pads underneath form the capacitive sensing electrodes.
+ *
+ * Related issue: tscircuit/tscircuit#786
+ */
+
+/**
+ * Generate a diamond (rhombus) polygon centered at offsetX, offsetY
+ */
+function diamondPoints(
+  halfWidth: number,
+  halfHeight: number,
+  offsetX = 0,
+  offsetY = 0,
+) {
+  return [
+    { x: offsetX, y: offsetY + halfHeight },
+    { x: offsetX + halfWidth, y: offsetY },
+    { x: offsetX, y: offsetY - halfHeight },
+    { x: offsetX - halfWidth, y: offsetY },
+  ]
+}
+
+test("capacitive touch slider - 5 segment polygon smtpads with soldermask", () => {
+  const { project } = getTestFixture()
+
+  const NUM_PADS = 5
+  const PAD_HALF_WIDTH = 1.2 // mm
+  const PAD_HALF_HEIGHT = 2.5 // mm
+  const SPACING = 3.0 // mm, center-to-center spacing
+
+  project.add(
+    <board width={`${NUM_PADS * SPACING + 4}mm`} height="10mm">
+      <chip
+        name="U1"
+        footprint={
+          <footprint>
+            {Array.from({ length: NUM_PADS }, (_, i) => {
+              const offsetX = (i - (NUM_PADS - 1) / 2) * SPACING
+              return (
+                <smtpad
+                  name={`pad${i + 1}`}
+                  shape="polygon"
+                  points={diamondPoints(
+                    PAD_HALF_WIDTH,
+                    PAD_HALF_HEIGHT,
+                    offsetX,
+                    0,
+                  )}
+                  portHints={[`pin${i + 1}`]}
+                  coveredWithSolderMask={true}
+                />
+              )
+            })}
+          </footprint>
+        }
+      />
+    </board>,
+  )
+
+  project.render()
+
+  const pads = project.db.pcb_smtpad.list()
+
+  // Verify all 5 pads exist
+  expect(pads).toHaveLength(NUM_PADS)
+
+  // Verify all pads are polygon shape and covered with solder mask
+  for (const pad of pads) {
+    expect(pad.shape).toBe("polygon")
+    expect(pad.is_covered_with_solder_mask).toBe(true)
+  }
+
+  // No solder paste should be generated for covered pads
+  expect(project.db.pcb_solder_paste.list()).toHaveLength(0)
+
+  // Each pad should have the correct number of polygon points (4 for diamond)
+  for (const pad of pads) {
+    if (pad.shape === "polygon") {
+      expect(pad.points).toHaveLength(4)
+    }
+  }
+
+  // Compute polygon centroids and verify they are distinct (pads spread along slider)
+  const centroids = pads.map((pad) => {
+    if (pad.shape === "polygon") {
+      const pts = pad.points
+      const cx = pts.reduce((s, p) => s + p.x, 0) / pts.length
+      return Math.round(cx * 100) / 100
+    }
+    return 0
+  })
+  const uniqueCentroids = new Set(centroids)
+  expect(uniqueCentroids.size).toBe(NUM_PADS)
+
+  expect(project).toMatchPcbSnapshot(import.meta.path)
+})