diff --git a/tests/validate-config.test.mjs b/tests/validate-config.test.mjs
index 630bb580..a974578b 100644
--- a/tests/validate-config.test.mjs
+++ b/tests/validate-config.test.mjs
@@ -3,13 +3,22 @@ import { test } from "node:test";
 
 import { validateInstanceConfig } from "../config/validate-config.js";
 
+// Common valid overrides to use as a base
+const VALID_OVERRIDES = {
+  ADMIN_SUPER_NPUB: "npub1qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq",
+  PLATFORM_FEE_PERCENT: 5,
+  PLATFORM_LUD16_OVERRIDE: "test@example.com",
+};
+
+test("validateInstanceConfig succeeds with valid configuration", () => {
+  assert.doesNotThrow(() => validateInstanceConfig(VALID_OVERRIDES));
+});
+
 test(
   "validateInstanceConfig throws when platform fee is positive without a platform override",
   () => {
     const overrides = {
-      ADMIN_SUPER_NPUB:
-        "npub1qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq",
-      PLATFORM_FEE_PERCENT: 5,
+      ...VALID_OVERRIDES,
       PLATFORM_LUD16_OVERRIDE: "   ",
     };
 
@@ -19,3 +28,108 @@ test(
     });
   }
 );
+
+test("validateInstanceConfig throws when ADMIN_SUPER_NPUB is empty", () => {
+  const overrides = {
+    ...VALID_OVERRIDES,
+    ADMIN_SUPER_NPUB: "   ",
+  };
+
+  assert.throws(() => validateInstanceConfig(overrides), {
+    message: /ADMIN_SUPER_NPUB is required/,
+  });
+});
+
+test("validateInstanceConfig throws when ADMIN_SUPER_NPUB does not start with npub", () => {
+  const overrides = {
+    ...VALID_OVERRIDES,
+    ADMIN_SUPER_NPUB: "invalid_npub",
+  };
+
+  assert.throws(() => validateInstanceConfig(overrides), {
+    message: /ADMIN_SUPER_NPUB should be a bech32 npub/,
+  });
+});
+
+test("validateInstanceConfig throws when PLATFORM_FEE_PERCENT is negative", () => {
+  const overrides = {
+    ...VALID_OVERRIDES,
+    PLATFORM_FEE_PERCENT: -1,
+  };
+
+  assert.throws(() => validateInstanceConfig(overrides), {
+    message: /PLATFORM_FEE_PERCENT must be between 0 and 100 inclusive/,
+  });
+});
+
+test("validateInstanceConfig throws when PLATFORM_FEE_PERCENT is greater than 100", () => {
+  const overrides = {
+    ...VALID_OVERRIDES,
+    PLATFORM_FEE_PERCENT: 101,
+  };
+
+  assert.throws(() => validateInstanceConfig(overrides), {
+    message: /PLATFORM_FEE_PERCENT must be between 0 and 100 inclusive/,
+  });
+});
+
+test("validateInstanceConfig throws when PLATFORM_FEE_PERCENT is not finite", () => {
+  const overrides = {
+    ...VALID_OVERRIDES,
+    PLATFORM_FEE_PERCENT: Infinity,
+  };
+
+  assert.throws(() => validateInstanceConfig(overrides), {
+    message: /PLATFORM_FEE_PERCENT must be a finite number/,
+  });
+});
+
+test("validateInstanceConfig throws when THEME_ACCENT_OVERRIDES has invalid hex color", () => {
+  const overrides = {
+    ...VALID_OVERRIDES,
+    THEME_ACCENT_OVERRIDES: {
+      light: {
+        accent: "invalid-hex",
+      },
+    },
+  };
+
+  assert.throws(() => validateInstanceConfig(overrides), {
+    message: /must be a #RRGGBB hex color/,
+  });
+});
+
+test("validateInstanceConfig throws when THEME_ACCENT_OVERRIDES structure is invalid", () => {
+  const overrides = {
+    ...VALID_OVERRIDES,
+    THEME_ACCENT_OVERRIDES: {
+      light: "not-an-object",
+    },
+  };
+
+  assert.throws(() => validateInstanceConfig(overrides), {
+    message: /must be an object with accent overrides/,
+  });
+});
+
+test("validateInstanceConfig throws when optional URL is invalid", () => {
+  const overrides = {
+    ...VALID_OVERRIDES,
+    BLOG_URL: "not-a-valid-url",
+  };
+
+  assert.throws(() => validateInstanceConfig(overrides), {
+    message: /BLOG_URL must be a valid http\(s\) URL/,
+  });
+});
+
+test("validateInstanceConfig throws when optional URL has invalid protocol", () => {
+  const overrides = {
+    ...VALID_OVERRIDES,
+    BLOG_URL: "ftp://example.com",
+  };
+
+  assert.throws(() => validateInstanceConfig(overrides), {
+    message: /BLOG_URL must be a valid http\(s\) URL/,
+  });
+});