From 2dca43177b9e66a7c4632270359210f19ed0b8a5 Mon Sep 17 00:00:00 2001
From: "Sharad." <sharadvc@users.noreply.github.com>
Date: Sat, 12 Sep 2026 14:20:44 +0000
Subject: [PATCH] Fix contains scorer passing on empty needle

Reject empty substrings so misconfigured value: "" does not trivially pass.

Fixes #28

Co-authored-by: Sharad. <sharadvc@users.noreply.github.com>
---
 src/scorers/contains.ts | 4 ++--
 tests/scorers.test.ts   | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/scorers/contains.ts b/src/scorers/contains.ts
index ae4e64f..bf219d6 100644
--- a/src/scorers/contains.ts
+++ b/src/scorers/contains.ts
@@ -18,7 +18,7 @@ function asList(value: unknown): string[] {
 export const containsScorer: Scorer = {
   type: "contains",
   score(spec: ScorerSpec, ctx: ScoreContext) {
-    const needles = [...asList(spec.value), ...asList(spec.values)];
+    const needles = [...asList(spec.value), ...asList(spec.values)].filter((n) => n.length > 0);
     if (needles.length === 0) {
       return result(spec, { score: 0, passed: false, reason: "no value(s) provided" });
     }
@@ -44,7 +44,7 @@ export const containsScorer: Scorer = {
 export const notContainsScorer: Scorer = {
   type: "not-contains",
   score(spec: ScorerSpec, ctx: ScoreContext) {
-    const needles = [...asList(spec.value), ...asList(spec.values)];
+    const needles = [...asList(spec.value), ...asList(spec.values)].filter((n) => n.length > 0);
     if (needles.length === 0) {
       return result(spec, { score: 0, passed: false, reason: "no value(s) provided" });
     }
diff --git a/tests/scorers.test.ts b/tests/scorers.test.ts
index 78bf373..f2c0102 100644
--- a/tests/scorers.test.ts
+++ b/tests/scorers.test.ts
@@ -68,6 +68,10 @@ describe("regex", () => {
 });
 
 describe("contains / not-contains", () => {
+  it("fails when needle is an empty string", async () => {
+    const r = await run(containsScorer, { type: "contains", value: "" }, ctx("anything"));
+    expect(r.passed).toBe(false);
+  });
   it("gives partial credit when some substrings missing", async () => {
     const r = await run(containsScorer, { type: "contains", values: ["a", "b", "c"] }, ctx("a and b"));
     expect(r.passed).toBe(false);