test: add tests for IEEE 754-2019 compliance

---
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---

Author: anandkaranubc

lib/node_modules/@stdlib/math/base/special/cosd/test/test.js

@@ -114,3 +114,15 @@ tape( 'if provided `90.0`, the function returns `0.0`', function test( t ) {
 	t.equal( v, 0.0, 'returns expected value' );
 	t.end();
 });
+
+tape( 'the function returns `1` if provided `+-0`', function test( t ) {
+	var v;
+
+	v = cosd( -0.0 );
+	t.equal( v, 1.0, 'returns expected value' );
+
+	v = cosd( +0.0 );
+	t.equal( v, 1.0, 'returns expected value' );
+
+	t.end();
+});

lib/node_modules/@stdlib/math/base/special/cosd/test/test.native.js

@@ -123,3 +123,15 @@ tape( 'if provided `90.0`, the function returns `0.0`', opts, function test( t )
 	t.equal( v, 0.0, 'returns expected value' );
 	t.end();
 });
+
+tape( 'the function returns `1` if provided `+-0`', opts, function test( t ) {
+	var v;
+
+	v = cosd( -0.0 );
+	t.equal( v, 1.0, 'returns expected value' );
+
+	v = cosd( +0.0 );
+	t.equal( v, 1.0, 'returns expected value' );
+
+	t.end();
+});