From 796226a218a46057579740527dc3e81acca04774 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 20 Jan 2026 15:01:22 +0000
Subject: [PATCH 1/2] Initial plan


From a4f772cba03754aef405e02fa3df74df6cf67c0e Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 20 Jan 2026 15:05:13 +0000
Subject: [PATCH 2/2] Add comprehensive unit tests for add function covering
 all branches

Co-authored-by: Sander-Toonen <5106372+Sander-Toonen@users.noreply.github.com>
---
 test/functions/functions-binary-ops.ts | 46 ++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/test/functions/functions-binary-ops.ts b/test/functions/functions-binary-ops.ts
index 53d47a51..12aaa5a5 100644
--- a/test/functions/functions-binary-ops.ts
+++ b/test/functions/functions-binary-ops.ts
@@ -16,6 +16,52 @@ describe('Binary Operators TypeScript Test', function () {
       assert.strictEqual(parser.evaluate('2 + undefined'), undefined);
       assert.strictEqual(parser.evaluate('undefined + 2'), undefined);
     });
+    it('should concatenate non-numeric strings', function () {
+      const parser = new Parser();
+      assert.strictEqual(parser.evaluate('"hello" + "world"'), 'helloworld');
+      assert.strictEqual(parser.evaluate('"foo" + "bar"'), 'foobar');
+      assert.strictEqual(parser.evaluate('"test" + "123"'), 'test123');
+    });
+    it('should add numeric strings as numbers', function () {
+      const parser = new Parser();
+      assert.strictEqual(parser.evaluate('"5" + "3"'), 8);
+      assert.strictEqual(parser.evaluate('"10" + "20"'), 30);
+      assert.strictEqual(parser.evaluate('"0" + "5"'), 5);
+    });
+    it('should concatenate arrays', function () {
+      const parser = new Parser();
+      assert.deepStrictEqual(parser.evaluate('[1, 2] + [3, 4]'), [1, 2, 3, 4]);
+      assert.deepStrictEqual(parser.evaluate('[1] + [2, 3]'), [1, 2, 3]);
+      assert.deepStrictEqual(parser.evaluate('[] + [1, 2]'), [1, 2]);
+    });
+    it('should merge objects', function () {
+      const parser = new Parser();
+      assert.deepStrictEqual(parser.evaluate('{a: 1} + {b: 2}'), { a: 1, b: 2 });
+      assert.deepStrictEqual(parser.evaluate('{x: 10} + {y: 20}'), { x: 10, y: 20 });
+      assert.deepStrictEqual(parser.evaluate('{a: 1, b: 2} + {c: 3}'), { a: 1, b: 2, c: 3 });
+    });
+    it('should handle object merging with overlapping keys', function () {
+      const parser = new Parser();
+      assert.deepStrictEqual(parser.evaluate('{a: 1} + {a: 2}'), { a: 2 });
+      assert.deepStrictEqual(parser.evaluate('{x: 10, y: 20} + {y: 30}'), { x: 10, y: 30 });
+    });
+    it('should handle null values correctly', function () {
+      const parser = new Parser();
+      assert.deepStrictEqual(parser.evaluate('null + null'), {});
+    });
+    it('should convert numeric values to numbers before adding', function () {
+      const parser = new Parser();
+      assert.strictEqual(parser.evaluate('true + 1'), 2);
+      assert.strictEqual(parser.evaluate('false + 5'), 5);
+      assert.strictEqual(parser.evaluate('1 + true'), 2);
+    });
+    it('should throw error for incompatible types', function () {
+      const parser = new Parser();
+      assert.throws(() => parser.evaluate('5 + [1, 2]'), /Cannot add values of incompatible types/);
+      assert.throws(() => parser.evaluate('"text" + {a: 1}'), /Cannot add values of incompatible types/);
+      assert.throws(() => parser.evaluate('[1, 2] + {a: 1}'), /Cannot add values of incompatible types/);
+      assert.throws(() => parser.evaluate('5 + {x: 1}'), /Cannot add values of incompatible types/);
+    });
   });
 
   describe('- (subtraction)', function () {