5 files changed, 39 insertions, 4 deletions
diff --git a/tests/integration/repl_tests.rs b/tests/integration/repl_tests.rs
index 4e00398ce..9eceb2f05 100644
--- a/tests/integration/repl_tests.rs
+++ b/tests/integration/repl_tests.rs
@@ -255,6 +255,20 @@ fn console_log() {
     console.write_line("'world'");
     console.expect("\"world\"");
   });
+
+  // https://github.com/denoland/deno/issues/21428
+  let (out, err) = util::run_and_collect_output_with_args(
+    true,
+    vec![
+      "repl",
+      "--eval-file=./../specs/repl/console_log/093_console_log_format.js",
+    ],
+    None,
+    None,
+    false,
+  );
+  assert_contains!(out, "0.5");
+  assert!(err.is_empty());
 }
 
 #[test]
diff --git a/tests/specs/repl/console_log/093_console_log_format.js b/tests/specs/repl/console_log/093_console_log_format.js
new file mode 100644
index 000000000..15022411c
--- /dev/null
+++ b/tests/specs/repl/console_log/093_console_log_format.js
@@ -0,0 +1,16 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+class Frac {
+  constructor(num, den) {
+    this.num = num;
+    this.den = den;
+  }
+  [Symbol.toPrimitive]() {
+    return this.num / this.den;
+  }
+  display() {
+    const result = this.num / this.den;
+    process.stdout.write(`${result}`);
+  }
+}
+const f = new Frac(1, 2);
+f.display();
diff --git a/tests/specs/repl/console_log/093_console_log_format.out b/tests/specs/repl/console_log/093_console_log_format.out
new file mode 100644
index 000000000..ea2303bc0
--- /dev/null
+++ b/tests/specs/repl/console_log/093_console_log_format.out
@@ -0,0 +1 @@
+0.5
+\ No newline at end of file
diff --git a/tests/specs/repl/console_log/__test__.jsonc b/tests/specs/repl/console_log/__test__.jsonc
new file mode 100644
index 000000000..641bc1f68
--- /dev/null
+++ b/tests/specs/repl/console_log/__test__.jsonc
@@ -0,0 +1,4 @@
+{
+  "args": "run -A --quiet 093_console_log_format.js",
+  "output": "093_console_log_format.out"
+}
diff --git a/tests/unit/console_test.ts b/tests/unit/console_test.ts
index 878d17ae3..42cff7c70 100644
--- a/tests/unit/console_test.ts
+++ b/tests/unit/console_test.ts
@@ -1162,7 +1162,7 @@ Deno.test(function consoleTestWithIntegerFormatSpecifier() {
   assertEquals(stringify("%i"), "%i");
   assertEquals(stringify("%i", 42.0), "42");
   assertEquals(stringify("%i", 42), "42");
-  assertEquals(stringify("%i", "42"), "NaN");
+  assertEquals(stringify("%i", "42"), "42");
   assertEquals(stringify("%i", 1.5), "1");
   assertEquals(stringify("%i", -0.5), "0");
   assertEquals(stringify("%i", ""), "NaN");
@@ -1172,7 +1172,7 @@ Deno.test(function consoleTestWithIntegerFormatSpecifier() {
   assertEquals(stringify("%d", 12345678901234567890123), "1");
   assertEquals(
     stringify("%i", 12345678901234567890123n),
-    "12345678901234567890123n",
+    "1.2345678901234568e+22",
   );
 });
 
@@ -1180,13 +1180,13 @@ Deno.test(function consoleTestWithFloatFormatSpecifier() {
   assertEquals(stringify("%f"), "%f");
   assertEquals(stringify("%f", 42.0), "42");
   assertEquals(stringify("%f", 42), "42");
-  assertEquals(stringify("%f", "42"), "NaN");
+  assertEquals(stringify("%f", "42"), "42");
   assertEquals(stringify("%f", 1.5), "1.5");
   assertEquals(stringify("%f", -0.5), "-0.5");
   assertEquals(stringify("%f", Math.PI), "3.141592653589793");
   assertEquals(stringify("%f", ""), "NaN");
   assertEquals(stringify("%f", Symbol("foo")), "NaN");
-  assertEquals(stringify("%f", 5n), "NaN");
+  assertEquals(stringify("%f", 5n), "5");
   assertEquals(stringify("%f %f", 42, 43), "42 43");
   assertEquals(stringify("%f %f", 42), "42 %f");
 });