test: add zeros tests

---
type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
report:
  - task: lint_filenames
    status: passed
  - task: lint_editorconfig
    status: passed
  - task: lint_markdown
    status: na
  - task: lint_package_json
    status: na
  - task: lint_repl_help
    status: na
  - task: lint_javascript_src
    status: na
  - task: lint_javascript_cli
    status: na
  - task: lint_javascript_examples
    status: na
  - task: lint_javascript_tests
    status: passed
  - task: lint_javascript_benchmarks
    status: na
  - task: lint_python
    status: na
  - task: lint_r
    status: na
  - task: lint_c_src
    status: na
  - task: lint_c_examples
    status: na
  - task: lint_c_benchmarks
    status: na
  - task: lint_c_tests_fixtures
    status: na
  - task: lint_shell
    status: na
  - task: lint_typescript_declarations
    status: na
  - task: lint_typescript_tests
    status: na
  - task: lint_license_headers
    status: passed
---

Author: kgryte

lib/node_modules/@stdlib/blas/ext/base/gnansumkbn2/test/test.ndarray.js

@@ -21,6 +21,7 @@
 // MODULES //
 
 var tape = require( 'tape' );
+var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
 var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
 var gnansumkbn2 = require( './../lib/ndarray.js' );
 
@@ -108,6 +109,40 @@ tape( 'the function calculates the sum of strided array elements (ignoring NaN v
 	t.end();
 });
 
+tape( 'the function does not preserve the sign of zero', function test( t ) {
+	var x;
+	var v;
+
+	x = [ -0.0, -0.0, -0.0 ];
+
+	v = gnansumkbn2( x.length, x, 1, 0 );
+	t.strictEqual( isPositiveZero( v ), true, 'returns expected value' );
+
+	x = [ 0.0, -0.0, -0.0 ];
+
+	v = gnansumkbn2( x.length, x, 1, 0 );
+	t.strictEqual( isPositiveZero( v ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'the function does not preserve the sign of zero (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = toAccessorArray( [ -0.0, -0.0, -0.0 ] );
+
+	v = gnansumkbn2( x.length, x, 1, 0 );
+	t.strictEqual( isPositiveZero( v ), true, 'returns expected value' );
+
+	x = toAccessorArray( [ 0.0, -0.0, -0.0 ] );
+
+	v = gnansumkbn2( x.length, x, 1, 0 );
+	t.strictEqual( isPositiveZero( v ), true, 'returns expected value' );
+
+	t.end();
+});
+
 tape( 'if provided an `N` parameter less than or equal to `0`, the function returns `0.0`', function test( t ) {
 	var x;
 	var v;