test: add tests to ndarray/base/count-if

PR-URL: stdlib-js#8318
Closes: stdlib-js/metr-issue-tracker#104
Co-authored-by: Athan Reines <kgryte@gmail.com>
Reviewed-by: Athan Reines <kgryte@gmail.com>

Author: headlessNode

lib/node_modules/@stdlib/ndarray/base/count-if/lib/main.js

@@ -193,7 +193,7 @@ function countIf( arrays, predicate, thisArg ) {
 	}
 	// Check whether we were provided an empty ndarray...
 	if ( numel( shx ) === 0 ) {
-		return true;
+		return 0;
 	}
 	// Determine whether we can avoid blocked iteration...
 	if ( ndims <= MAX_DIMS && iterationOrder( x.strides ) !== 0 ) {