diff --git a/test/js/bun/shell/file-io.test.ts b/test/js/bun/shell/file-io.test.ts
index 5b10f0351a8e..d85fddc954aa 100644
--- a/test/js/bun/shell/file-io.test.ts
+++ b/test/js/bun/shell/file-io.test.ts
@@ -225,14 +225,32 @@ describe("IOWriter file output redirection", () => {
     // command caused the same file descriptor to be closed twice, resulting
     // in an EBADF error. The issue was that two separate IOWriter instances
     // were created for the same fd when both stdout and stderr were redirected.
-    TestBuilder.command`pwd &> pwd_output.txt`.exitCode(0).runAsTest("builtin pwd with &> redirect");
+    TestBuilder.command`pwd &> pwd_output.txt`
+      .exitCode(0)
+      .fileEquals("pwd_output.txt", "$TEMP_DIR\n")
+      .runAsTest("builtin pwd with &> redirect");
 
     TestBuilder.command`echo "hello" &> echo_output.txt`
       .exitCode(0)
       .fileEquals("echo_output.txt", "hello\n")
       .runAsTest("builtin echo with &> redirect");
 
-    TestBuilder.command`pwd &>> append_output.txt`.exitCode(0).runAsTest("builtin pwd with &>> append redirect");
+    TestBuilder.command`pwd extra-arg &> stderr_output.txt`
+      .exitCode(1)
+      .stderr("")
+      .fileEquals("stderr_output.txt", "pwd: too many arguments\n")
+      .runAsTest("builtin stderr with &> redirect");
+
+    TestBuilder.command`pwd &>> append_output.txt`
+      .file("append_output.txt", "existing line\n")
+      .exitCode(0)
+      .fileEquals("append_output.txt", "existing line\n$TEMP_DIR\n")
+      .runAsTest("builtin pwd with &>> append redirect");
+
+    TestBuilder.command`pwd &>> new_append_output.txt`
+      .exitCode(0)
+      .fileEquals("new_append_output.txt", "$TEMP_DIR\n")
+      .runAsTest("builtin pwd with &>> redirect creates a missing file");
   });
 });
 
diff --git a/test/js/bun/shell/test_builder.ts b/test/js/bun/shell/test_builder.ts
index 64a90a805548..5d6033f3c74f 100644
--- a/test/js/bun/shell/test_builder.ts
+++ b/test/js/bun/shell/test_builder.ts
@@ -171,6 +171,10 @@ export function createTestBuilder(path: string) {
       return this;
     }
 
+    /**
+     * Expect a file in the temp directory to have the given contents. Like
+     * `stdout()`, a string `expected` has `$TEMP_DIR` replaced with the temp directory.
+     */
     fileEquals(filename: string, expected: string | (() => string | Promise<string>)): this {
       this.getTempDir();
       this.file_equals[filename] = expected;
@@ -228,7 +232,8 @@ export function createTestBuilder(path: string) {
       } else if (typeof this.expected_exit_code === "function") this.expected_exit_code(exitCode);
 
       for (const [filename, expected_raw] of Object.entries(this.file_equals)) {
-        const expected = typeof expected_raw === "string" ? expected_raw : await expected_raw();
+        const expected =
+          typeof expected_raw === "string" ? expected_raw.replaceAll("$TEMP_DIR", tempdir) : await expected_raw();
         const actual = await Bun.file(join(this.tempdir!, filename)).text();
         expect(actual).toEqual(expected);
       }
@@ -256,7 +261,7 @@ export function createTestBuilder(path: string) {
           if (stdout === undefined || stderr === undefined || exitCode === undefined) {
             throw err_;
           }
-          this.doChecks(stdout, stderr, exitCode);
+          await this.doChecks(stdout, stderr, exitCode);
           return;
         }
         if (this.expected_error === true) return undefined;