test : added unit tests for scorePrMergeRate function

test/repo-health.test.js

@@ -0,0 +1,38 @@
+const assert = require("node:assert/strict");
+const test = require("node:test");
+
+function clamp(n, min, max) {
+  if (!Number.isFinite(n)) {
+    return min;
+  }
+  return Math.min(max, Math.max(min, n));
+}
+
+function scorePrMergeRate(rate) {
+  return clamp(rate, 0, 1) * 25;
+}
+
+test("scorePrMergeRate returns 0 for rate 0", () => {
+  assert.equal(scorePrMergeRate(0), 0);
+});
+
+test("scorePrMergeRate returns 25 for rate 1", () => {
+  assert.equal(scorePrMergeRate(1), 25);
+});
+
+test("scorePrMergeRate scales linearly for rate 0-1", () => {
+  assert.equal(scorePrMergeRate(0.5), 12.5);
+  assert.equal(scorePrMergeRate(0.25), 6.25);
+});
+
+test("scorePrMergeRate clamps negative rates to 0", () => {
+  assert.equal(scorePrMergeRate(-0.5), 0);
+});
+
+test("scorePrMergeRate clamps rates above 1 to 25", () => {
+  assert.equal(scorePrMergeRate(1.5), 25);
+});
+
+test("scorePrMergeRate handles non-finite values", () => {
+  assert.equal(scorePrMergeRate(NaN), 0);
+});