fix(@angular/build): support injecting global styles into vitest unit-tests

Author: clydin

packages/angular/build/src/builders/unit-test/builder.ts

@@ -257,6 +257,25 @@ export async function* execute(
                 ];
               },
             },
+            {
+              name: 'angular-html-index',
+              transformIndexHtml() {
+                // Add all global stylesheets
+                return (
+                  Object.entries(result.files)
+                    // TODO: Expand this to all configured global stylesheets
+                    .filter(([file]) => file === 'styles.css')
+                    .map(([styleUrl]) => ({
+                      tag: 'link',
+                      attrs: {
+                        'href': styleUrl,
+                        'rel': 'stylesheet',
+                      },
+                      injectTo: 'head',
+                    }))
+                );
+              },
+            },
           ],
         },
       );