diff --git a/.drone.yml b/.drone.yml
index a2f4d8f..d98fb55 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -12,5 +12,4 @@ steps:
   image: node
   commands:
   - yarn install
-  - yarn build
   - yarn test
\ No newline at end of file
diff --git a/package.json b/package.json
index 5b05782..603afc8 100644
--- a/package.json
+++ b/package.json
@@ -22,7 +22,7 @@
   ],
   "scripts": {
     "build": "tsc",
-    "test": "jest",
+    "test": "tsc && jest",
     "release": "tsc && yarn publish",
     "lint": "eslint --fix"
   }
diff --git a/src/classes/Command.ts b/src/classes/Command.ts
index 88057e6..0db5e14 100644
--- a/src/classes/Command.ts
+++ b/src/classes/Command.ts
@@ -15,6 +15,9 @@ abstract class Command implements ICommand {
 
     constructor(def: CommandDefinition) {
 
+        if (typeof def !== 'object') throw new Error('Missing command definition');
+        
+        if (!def.name) throw new Error('Missing name for command');
         this.name = def.name;
 
         this.aliases = def.aliases || [];
@@ -24,6 +27,8 @@ abstract class Command implements ICommand {
             if (opt instanceof CommandOption) this.options.push(opt);
             else this.options.push(new CommandOption(opt));
         }
+        if (this.options.some(opt => [OptionType.SUB_COMMAND, OptionType.SUB_COMMAND_GROUP].includes(opt.type))
+            && this.options.some(opt => ![OptionType.SUB_COMMAND, OptionType.SUB_COMMAND_GROUP].includes(opt.type))) throw new Error('Cannot have subcommand(group)s on the same level as an option')
 
     }
 
diff --git a/src/classes/CommandOption.ts b/src/classes/CommandOption.ts
index efba9fd..0a96329 100644
--- a/src/classes/CommandOption.ts
+++ b/src/classes/CommandOption.ts
@@ -49,17 +49,27 @@ class CommandOption implements ICommandOption {
         this.name = def.name;
         this.aliases = def.aliases || [];
 
+        this.strict = def.strict || false;
+        this.type = def.type ?? OptionType.STRING;
+        this.flag = def.flag || false;
+
         this.options = [];
         for (const opt of def.options || []) {
             if (opt instanceof CommandOption) this.options.push(opt);
             else this.options.push(new CommandOption(opt));
         }
+
+        if (this.type === OptionType.SUB_COMMAND_GROUP && this.options.some(opt => opt.type === OptionType.SUB_COMMAND_GROUP)) throw new Error('Cannot nest subcommand groups');
+        if (this.type === OptionType.SUB_COMMAND && this.options.some(opt => opt.type === OptionType.SUB_COMMAND_GROUP)) throw new Error('Cannot have subcommand groups under a subcommand');
+        if (this.type === OptionType.SUB_COMMAND && this.options.some(opt => opt.type === OptionType.SUB_COMMAND)) throw new Error('Cannot nest subcommands');
+        if (![OptionType.SUB_COMMAND, OptionType.SUB_COMMAND_GROUP].includes(this.type)
+            && this.options.some(opt => [OptionType.SUB_COMMAND, OptionType.SUB_COMMAND_GROUP].includes(opt.type))) throw new Error('Cannot have subcommand(group)s under an option');
+
+        if (this.options.some(opt => [OptionType.SUB_COMMAND, OptionType.SUB_COMMAND_GROUP].includes(opt.type))
+            && this.options.some(opt => ![OptionType.SUB_COMMAND, OptionType.SUB_COMMAND_GROUP].includes(opt.type))) throw new Error('Cannot have subcommand(group)s on the same level as an option')
+
         this.choices = def.choices || [];
         
-        this.strict = def.strict || false;
-        this.type = def.type ?? OptionType.STRING;
-        this.flag = def.flag || false;
-
         this.valueOptional = def.valueOptional || false;
         this.defaultValue = def.defaultValue ?? null;
         this.valueAsAlias = def.valueAsAlias || false;
diff --git a/tests/CommandOption.test.js b/tests/CommandOption.test.js
index 1e0b73e..e876e09 100644
--- a/tests/CommandOption.test.js
+++ b/tests/CommandOption.test.js
@@ -20,7 +20,7 @@ const parser = new Parser({
 
 (async () => {
     const parsed = await parser.parseMessage('test message.author')
-    console.log(parsed)
+    // console.log(parsed)
 })();
 
 test('', () => {
diff --git a/tests/Parser.test.js b/tests/Parser.test.js
index b35a775..8b0f8cf 100644
--- a/tests/Parser.test.js
+++ b/tests/Parser.test.js
@@ -1,11 +1,70 @@
 const { inspect } = require('node:util');
 const { Parser, Command, OptionType } = require('../build');
 
+test('Command definition', () => {
+    expect(() => new Command()).toThrow();
+    expect(() => new Command({})).toThrow();
+    expect(() => new Command(235345)).toThrow();
+    expect(() => new Command({ name: 'create' })).not.toThrow();
+    
+    expect(() => new Command({
+        name: 'create',
+        options: [{
+            name: 'test',
+            type: OptionType.SUB_COMMAND,
+            options: [{
+                name:'dingus',
+                type: OptionType.SUB_COMMAND
+            }]
+        }]
+    })).toThrow();
+
+    expect(() => new Command({
+        name: 'create',
+        options: [{
+            name: 'test',
+            type: OptionType.STRING,
+            options: [{
+                name:'dingus',
+                type: OptionType.SUB_COMMAND
+            }]
+        }]
+    })).toThrow();
+    
+    expect(() => new Command({
+        name: 'create',
+        options: [{
+            name: 'test',
+            type: OptionType.SUB_COMMAND_GROUP,
+            options: [{
+                name:'dingus',
+                type: OptionType.SUB_COMMAND
+            }]
+    }] })).not.toThrow();
+})
 
 test('Command Parser', async () => {
-    const command = new Command({ name: 'create', options: [{ name: 'registration-code', aliases: ['code'], type: OptionType.SUB_COMMAND }, { name: 'test' }] });
+    const command = new Command({
+        name: 'create',
+        options: [{
+            name: 'registration-code',
+            aliases: ['code'],
+            type: OptionType.SUB_COMMAND,
+            options: [{
+                name: 'amount',
+                type: OptionType.INTEGER,
+                defaultValue: 1,
+                valueOptional: true
+            }]
+        }]
+    });
     const parser = new Parser({ commands: [command], prefix: '' });
 
     await expect(parser.parseMessage('create')).rejects.toThrow();
+    // Cannot have an option at the sub-command level
+    await expect(parser.parseMessage('create test')).rejects.toThrow();
+
+    await expect(parser.parseMessage('create code')).resolves.toHaveProperty('command.name', 'create');
+    await expect(parser.parseMessage('create code 1')).resolves.toHaveProperty('args.amount.value', 1);
 
 });
\ No newline at end of file