Clarify literals handling

Author: hoijnet

lib/query/woqlBuilder.js

@@ -86,9 +86,9 @@ WOQLQuery.prototype.boolean = function (tf) {
 };
 
 /**
- * @param {any} s
- * @param {string} t
- * @returns {object}
+ * @param {any} s - the value of the literal
+ * @param {string} t - the type of the literal, e.g. 'xsd:string', 'xsd:boolean'
+ * @returns {object} - a WOQL DataValue object with the given type and value
  */
 WOQLQuery.prototype.literal = function (s, t) {
   t = t.indexOf(':') === -1 ? `xsd:${t}` : t;

test/woqlLiteral.spec.js

@@ -0,0 +1,25 @@
+const { expect } = require('chai');
+const WOQL = require('../lib/woql');
+
+describe('WOQL.literal() tests', () => {
+  it('should correctly wrap literal value 0 with xsd:double in DataValue structure', () => {
+    const result = WOQL.eq("v:var", WOQL.literal(0, 'xsd:double'));
+
+    const expected = {
+      '@type': 'Equals',
+      'left': {
+        '@type': 'Value',
+        'variable': 'var'
+      },
+      'right': {
+        '@type': 'Value',
+        'data': {
+          '@type': 'xsd:double',
+          '@value': 0
+        }
+      }
+    };
+
+    expect(result.query).to.eql(expected);
+  });
+});