before functional changes by codex

test/basic/specific-constructor.basic.test.js

@@ -0,0 +1,16 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+
+const { makeMeasurementInstance } = require('../helpers/factories');
+
+test('Measurement constructor initializes key defaults and ranges', () => {
+  const m = makeMeasurementInstance();
+
+  assert.equal(m.inputValue, 0);
+  assert.equal(m.outputAbs, 0);
+  assert.equal(m.outputPercent, 0);
+  assert.equal(Array.isArray(m.storedValues), true);
+  assert.equal(typeof m.measurements, 'object');
+  assert.equal(m.inputRange, 100);
+  assert.equal(m.processRange, 10);
+});