fix: allow t-attf- attributes to combine with regular attrs

fixes #10

src/qweb.ts

@@ -522,7 +522,10 @@ export class QWeb {
       const value = attributes[i].textContent!;
 
       // regular attributes
-      if (!name.startsWith("t-")) {
+      if (
+        !name.startsWith("t-") &&
+        !(<Element>node).getAttribute("t-attf-" + name)
+      ) {
         const attID = ctx.generateID();
         ctx.addLine(`let _${attID} = '${value}';`);
         if (!name.match(/^[a-zA-Z]+$/)) {
@@ -576,7 +579,14 @@ export class QWeb {
           s => "${" + ctx.formatExpression(s.slice(2, -2)) + "}"
         );
         const attID = ctx.generateID();
-        ctx.addLine(`let _${attID} = \`${formattedExpr}\`;`);
+        let staticVal = (<Element>node).getAttribute(attName);
+        if (staticVal) {
+          ctx.addLine(
+            `let _${attID} = '${staticVal} ' + \`${formattedExpr}\`;`
+          );
+        } else {
+          ctx.addLine(`let _${attID} = \`${formattedExpr}\`;`);
+        }
         attrs.push(`${attName}: _${attID}`);
       }
 

tests/__snapshots__/qweb.test.ts.snap

@@ -207,6 +207,17 @@ exports[`attributes t-att-class with object 1`] = `
 }"
 `;
 
+exports[`attributes t-attf-class should combine with class 1`] = `
+"function anonymous(context,extra
+) {
+    let h = this.utils.h;
+    let _1 = 'hello ' + \`world\`;
+    let c2 = [], p2 = {key:2,attrs:{class: _1}};
+    let vn2 = h('div', p2, c2);
+    return vn2;
+}"
+`;
+
 exports[`attributes tuple literal 1`] = `
 "function anonymous(context,extra
 ) {

tests/qweb.test.ts

@@ -401,6 +401,12 @@ describe("attributes", () => {
     expect(result).toBe(`<div foo="bar"></div>`);
   });
 
+  test("t-attf-class should combine with class", () => {
+    qweb.addTemplate("test", `<div class="hello" t-attf-class="world"/>`);
+    const result = renderToString(qweb, "test");
+    expect(result).toBe(`<div class="hello world"></div>`);
+  });
+
   test("format value", () => {
     qweb.addTemplate("test", `<div t-attf-foo="b{{value}}r"/>`);
     const result = renderToString(qweb, "test", { value: "a" });