Add comprehensive test coverage for beta version extraction (issue #286)

Co-authored-by: garrytrinder <11563347+garrytrinder@users.noreply.github.com>

Author: Copilot

src/test/extension.test.ts

@@ -655,4 +655,34 @@ info    v0.29.1`;
     const result = detect.extractVersionFromOutput(output);
     assert.strictEqual(result, '0.29.1');
   });
+
+  test('should not extract beta version from Unix file paths (issue #286)', () => {
+    const output = `info    1 error responses loaded from /opt/homebrew/Cellar/dev-proxy/v0.30.0-beta.2/devproxy-errors.json`;
+    
+    const result = detect.extractVersionFromOutput(output);
+    assert.strictEqual(result, '');
+  });
+
+  test('should not extract beta version from Windows file paths (issue #286)', () => {
+    const output = `info    1 error responses loaded from C:\\Program Files\\dev-proxy\\v0.30.0-beta.2\\devproxy-errors.json`;
+    
+    const result = detect.extractVersionFromOutput(output);
+    assert.strictEqual(result, '');
+  });
+
+  test('should extract beta version from update notification, ignoring file paths (issue #286)', () => {
+    const output = `info    1 error responses loaded from /opt/homebrew/Cellar/dev-proxy/v0.30.0-beta.1/devproxy-errors.json
+info    v0.30.0-beta.2`;
+    
+    const result = detect.extractVersionFromOutput(output);
+    assert.strictEqual(result, '0.30.0-beta.2');
+  });
+
+  test('should extract beta version from update notification with Windows paths in earlier lines (issue #286)', () => {
+    const output = `info    1 error responses loaded from C:\\Program Files\\dev-proxy\\v0.30.0-beta.1\\devproxy-errors.json
+info    v0.30.0-beta.2`;
+    
+    const result = detect.extractVersionFromOutput(output);
+    assert.strictEqual(result, '0.30.0-beta.2');
+  });
 });