Workaround PATH casing issues on Windows

src/testing-utils.ts

@@ -63,6 +63,16 @@ export function setupTests(test: TestFn<any>) {
     t.context.stderrWrite = processStderrWrite;
     process.stderr.write = wrapOutput(t.context) as any;
 
+    // Workaround an issue in tests where the case insensitivity of the `$PATH`
+    // environment variable on Windows isn't preserved, i.e. `process.env.PATH`
+    // is not the same as `process.env.Path`.
+    const pathKeys = Object.keys(process.env).filter(
+      (k) => k.toLowerCase() === "path"
+    );
+    if (pathKeys.length > 0) {
+      process.env.PATH = process.env[pathKeys[0]];
+    }
+
     // Many tests modify environment variables. Take a copy now so that
     // we reset them after the test to keep tests independent of each other.
     // process.env only has strings fields, so a shallow copy is fine.