Add env var utils function for tests

Author: cderv

tests/utils.ts

@@ -190,3 +190,17 @@ export function fileLoader(...path: string[]) {
 export function quartoDevCmd(): string {
   return Deno.build.os === "windows" ? "quarto.cmd" : "quarto";
 }
+
+export function setEnvVar(name: string, value: string): string | undefined {
+  const originalValue = Deno.env.get(name);
+  Deno.env.set(name, value);
+  return originalValue;
+}
+
+export function restoreEnvVar(name: string, originalValue: string | undefined): void {
+  if (originalValue !== undefined) {
+    Deno.env.set(name, originalValue);
+  } else {
+    Deno.env.delete(name);
+  }
+}