diff --git a/encoding/_util_test.ts b/encoding/_util_test.ts
index ae80d1ae3..d24e68348 100644
--- a/encoding/_util_test.ts
+++ b/encoding/_util_test.ts
@@ -51,4 +51,11 @@ Deno.test("validateBinaryLike with invalid inputs", () => {
     TypeError,
     "The input must be a Uint8Array, a string, or an ArrayBuffer. Received a value of the type MyClass.",
   );
+  assertThrows(
+    () => {
+      validateBinaryLike(Object.create(null));
+    },
+    TypeError,
+    "The input must be a Uint8Array, a string, or an ArrayBuffer. Received a value of the type object.",
+  );
 });
diff --git a/encoding/ascii85_test.ts b/encoding/ascii85_test.ts
index 5f7f8d702..1e25dbbd3 100644
--- a/encoding/ascii85_test.ts
+++ b/encoding/ascii85_test.ts
@@ -192,3 +192,21 @@ Deno.test({
     assertEquals(encoded2, "F)YQ)");
   },
 });
+
+Deno.test({
+  name: `[encoding/ascii85] decode with default standard`,
+  fn() {
+    const tests = [
+      ["<~FCfN8Bl7P~>", "testing"],
+      ["<~A7]XsCgh3l~>", "denoland"],
+      ["<~@<5pmBfIsm@:X:cAH~>", "ascii85 adobe"],
+    ];
+
+    for (const [input, expect] of tests) {
+      assertEquals(
+        decodeAscii85(input),
+        utf8encoder.encode(expect),
+      );
+    }
+  },
+});
diff --git a/encoding/base32_test.ts b/encoding/base32_test.ts
index ba6d6eee8..3b827c48b 100644
--- a/encoding/base32_test.ts
+++ b/encoding/base32_test.ts
@@ -1,8 +1,8 @@
 // Test cases copied from https://github.com/LinusU/base32-encode/blob/master/test.js
 // Copyright (c) 2016-2017 Linus Unnebäck. MIT license.
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
-import { assert, assertEquals } from "../assert/mod.ts";
-import { decodeBase32, encodeBase32 } from "./base32.ts";
+import { assert, assertEquals, assertExists } from "../assert/mod.ts";
+import { byteLength, decodeBase32, encodeBase32 } from "./base32.ts";
 
 // Lifted from https://stackoverflow.com/questions/38987784
 const fromHexString = (hexString: string): Uint8Array =>
@@ -135,3 +135,27 @@ Deno.test({
     assert(errorCaught);
   },
 });
+
+Deno.test({
+  name: "[encoding.base32] byteLength",
+  fn() {
+    const tests: [string, number][] = [
+      ["JBSWY3DPEBLW64TMMQ======", 11],
+      ["3X4A5PRBX4NR4EVGJROMNJ2LLWJN2===", 18],
+      ["WB2K5C467XQPC7ZXXTFN3YAG2A4ZS62ZZDX3AWW5", 25],
+      ["6L6CGGN5FFCXZTIB5DQZJ3U327UXFGFWMEG7JKYPHVN2UCZNPTHWTAU63N2O33Y=", 39],
+    ];
+
+    for (const [input, expect] of tests) {
+      assertEquals(byteLength(input), expect);
+    }
+  },
+});
+
+Deno.test({
+  name: "[encoding.base32] encode very long text",
+  fn() {
+    const data = "a".repeat(16400);
+    assertExists(encodeBase32(data));
+  },
+});
diff --git a/encoding/base64url_test.ts b/encoding/base64url_test.ts
index f0f26d74d..d0e470851 100644
--- a/encoding/base64url_test.ts
+++ b/encoding/base64url_test.ts
@@ -54,3 +54,20 @@ Deno.test("[decoding/base64url] base64url.decode throws on invalid input", () =>
     );
   }
 });
+
+Deno.test("[decoding/base64url] base64url.decode throws on illegal base64url string", () => {
+  const testsetIllegalBase64url = [
+    "w58De",
+    "Zm9vYmFyy",
+    "DPj8-ZD_DnwEg",
+    "SGVsbG8gV29ybGQ-_",
+  ];
+
+  for (const illegalBase64url of testsetIllegalBase64url) {
+    assertThrows(
+      () => decodeBase64Url(illegalBase64url),
+      TypeError,
+      "Illegal base64url string!",
+    );
+  }
+});
diff --git a/encoding/varint_test.ts b/encoding/varint_test.ts
index 453c86e97..b51cb8fc2 100644
--- a/encoding/varint_test.ts
+++ b/encoding/varint_test.ts
@@ -95,8 +95,11 @@ Deno.test("VarInt encode manual", () => {
     [Uint8Array.of(255, 255, 255, 255, 255, 255, 255, 255, 255, 1), 10],
   );
 });
+Deno.test("VarInt encode overflow uint64", () => {
+  assertThrows(() => encode(1e+30), RangeError, "overflows uint64");
+});
 Deno.test("VarInt encode overflow with negative", () => {
-  assertThrows(() => encode(-1), RangeError);
+  assertThrows(() => encode(-1), RangeError, "signed input given");
 });
 Deno.test("VarInt encode with offset", () => {
   let uint = new Uint8Array(3);