angle node kind of working

frontend/tests/angleMeasureGeometry.test.mjs

@@ -0,0 +1,62 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+
+import {
+  getAngleLabelBasePosition,
+  getAngleLabelPosition,
+  measureAngleDegrees,
+  moveAngleWidget,
+} from '../src/angleMeasureGeometry.js';
+
+test('measureAngleDegrees returns the included angle', () => {
+  assert.equal(measureAngleDegrees(0, 1, 0, 0, 1, 0), 90);
+  assert.ok(Math.abs(measureAngleDegrees(-1, 0, 0, 0, 1, 0) - 180) < 1e-9);
+});
+
+test('moveAngleWidget translates all points together', () => {
+  const moved = moveAngleWidget(
+    { x1: 0.2, y1: 0.7, xm: 0.5, ym: 0.5, x2: 0.8, y2: 0.3 },
+    0.1,
+    -0.2,
+  );
+
+  assert.deepEqual(moved, {
+    x1: 0.3,
+    y1: 0.5,
+    xm: 0.6,
+    ym: 0.3,
+    x2: 0.9,
+    y2: 0.1,
+  });
+});
+
+test('moveAngleWidget clamps whole-widget drags to the image bounds', () => {
+  const moved = moveAngleWidget(
+    { x1: 0.2, y1: 0.7, xm: 0.5, ym: 0.5, x2: 0.8, y2: 0.3 },
+    0.4,
+    -0.5,
+  );
+
+  assert.deepEqual(moved, {
+    x1: 0.4,
+    y1: 0.4,
+    xm: 0.7,
+    ym: 0.2,
+    x2: 1,
+    y2: 0,
+  });
+});
+
+test('getAngleLabelPosition follows the angle bisector and applies draggable offsets', () => {
+  const base = getAngleLabelBasePosition(0.2, 0.5, 0.5, 0.5, 0.5, 0.2);
+  assert.ok(base.x < 0.5);
+  assert.ok(base.y < 0.5);
+
+  const shifted = getAngleLabelPosition(
+    { x1: 0.2, y1: 0.5, xm: 0.5, ym: 0.5, x2: 0.5, y2: 0.2 },
+    -0.1,
+    0.05,
+  );
+  assert.ok(Math.abs(shifted.x - (base.x - 0.1)) < 1e-9);
+  assert.ok(Math.abs(shifted.y - (base.y + 0.05)) < 1e-9);
+});