Fix: render { value: 0 } as 0 in template expressions (#46)

* Fix: render { value: 0 } as 0 in template expressions

* Fix: handle nullish values in template sinks with ?? operator (maintainer feedback)

* test: move .value=0 tests to BehaviorSubject block (maintainer feedback)

Author: the-matrixneo

src/parser/parser.test.ts

@@ -205,6 +205,12 @@ describe('Parser', () => {
 					expect(template).toEqual(`<div>${num}</div>`);
 				});
 
+				it('renders 0 for { value: 0 } expressions', () => {
+					const expr = { value: 0 };
+					const template = rml`<div>${expr}</div>`;
+					expect(template).toEqual('<div>0</div>');
+				});
+
 				it('handles -0 as "0"', () => {
 					// Don't ask why, it's a JavaScript quirk
 					const num = -0;
@@ -558,29 +564,36 @@ describe('Parser', () => {
 		describe('Any sink', () => {
 
 			describe('When a BehaviorSubject (.value) is passed', () => {
-
 				describe('When an implicit sink is used', () => {
-
 					it('sets the value inline', () => {
 						const bs = new BehaviorSubject(123)
 						const template = rml`<div>${bs}</div>`;
-
 						expect(template).toMatch(/<div.*>123<\/div>/);
 					});
-
 				});
-
 				describe('When an explicit sink is used', () => {
-
 					it('sets the value inline', () => {
 						const bs = new BehaviorSubject(123)
 						const template = rml`<div>${InnerText(bs)}</div>`;
-
 						expect(template).toMatch(/<div.*>123<\/div>/);
 					});
+				});
 
+				describe('Content', () => {
+					it('renders 0 when an object has a .value of 0', () => {
+						const zeroValueObject = { value: 0 };
+						const template = rml`<div>${zeroValueObject}</div>`;
+						expect(template).toEqual('<div>0</div>');
+					});
 				});
 
+				describe('Attributes', () => { 
+					it('renders 0 in an attribute when an object has a .value of 0', () => {
+						const zeroValueObject = { value: 0 };
+						const template = rml`<input value="${zeroValueObject}">`;
+						expect(template).toEqual(`<input value="0">`);
+					});
+				});
 			});
 
 		});

src/parser/parser.ts

@@ -68,14 +68,20 @@ const getEventName = (eventAttributeString: RMLEventAttributeName): [RMLEventNam
  *     <input type="number" value="${number}">
  *   `;
  * };
- * ```
- * 
- * ## Example
- *
- * ```ts
- * import { rml } from 'rimmel';
- *
- * const Component = () => {
+        if(['string', 'number', 'boolean'].includes(printableExpressionType)) {
+            acc = accPlusString +(expression ?? '');
+        } else if (
+            expression && typeof expression === 'object' &&
+            'value' in expression &&
+            (typeof expression.value === 'string' || typeof expression.value === 'number' || typeof expression.value === 'boolean')
+        ) {
+            // Render the value property of objects, including 0
+            acc = accPlusString + (expression.value ?? '');
+        } else {
+            //other existing logic for different expression types
+        }
+    }
+
  *   const data = fetch('/api').then(res => res.text());
  *
  *   return rml`
@@ -127,8 +133,13 @@ export function rml(strings: TemplateStringsArray, ...expressions: RMLTemplateEx
 		const printableExpressionType = typeof (expression ?? '');
 
 		if(['string', 'number', 'boolean'].includes(printableExpressionType)) {
-			// Static expressions, no data binding. Just concatenate and move on
 			acc = accPlusString +(expression ?? '');
+		} else if (
+			expression && typeof expression === 'object' &&
+			'value' in expression &&
+			(typeof expression.value === 'string' || typeof expression.value === 'number' || typeof expression.value === 'boolean')
+		) {
+			acc = accPlusString + (expression.value ?? '');
 		} else if(eventName) {
 			// Event Source
 			// so feed it to an Rx Subject | Observer | Handler Function | POJO | Array
@@ -268,7 +279,7 @@ export function rml(strings: TemplateStringsArray, ...expressions: RMLTemplateEx
 					addRef(ref, isSinkBindingConfiguration(_source) ? _source : InnerHTML(_source));
 					acc = acc
 						+(existingRef ? string : string.replace(/\s*>\s*$/, ` ${RESOLVE_ATTRIBUTE}="${ref}">`))
-						+(initialValue || '')
+						+(initialValue ?? '')
 					;
 
 				} else if(/>?\s*[^<]*$/m.test(string) && /^\s*[^<]*\s*<?/m.test(nextString)) {