Merge branch 'master' of https://github.com/nestjs/docs.nestjs.com

Author: kamilmysliwiec

.nvmrc

@@ -1 +1 @@
-12.18.2
+12.18.3

content/enterprise.md

@@ -21,13 +21,13 @@ With official support, get expert help directly from the NestJS core team. We ta
     </p>
   </div>
   <div class="thumbnail p-l-30">
-    <img src="/assets/enterprise/help.svg">
+    <img src="/assets/enterprise/help.svg" />
   </div>
 </div>
 
 <div class="row">
 <div class="thumbnail p-r-30">
-    <img src="/assets/enterprise/contact.svg">
+    <img src="/assets/enterprise/contact.svg" />
   </div>
   <div class="content">
     <h4>NestJS Best Practices</h4>

content/fundamentals/unit-testing.md

@@ -256,30 +256,31 @@ Each of the override method types, in turn, returns the `TestingModule` instance
 The compiled module has several useful methods, as described in the following table:
 
 <table>
-    <tr>
-      <td>
-        <code>createNestApplication()</code>
-      </td>
-      <td>
-        Creates and returns a Nest application (<code>INestApplication</code> instance) based on the given module.
-        Note that you must manually initialize the application using the <code>init()</code> method.
-      </td>
-    </tr>
-    <tr>
-      <td>
-        <code>createNestMicroservice()</code>
-      </td>
-      <td>
-        Creates and returns a Nest microservice (<code>INestMicroservice</code> instance) based on the given module.
-      </td>
-    </tr>
-    <tr>
+  <tr>
+    <td>
+      <code>createNestApplication()</code>
+    </td>
+    <td>
+      Creates and returns a Nest application (<code>INestApplication</code> instance) based on the given module.
+      Note that you must manually initialize the application using the <code>init()</code> method.
+    </td>
+  </tr>
+  <tr>
+    <td>
+      <code>createNestMicroservice()</code>
+    </td>
+    <td>
+      Creates and returns a Nest microservice (<code>INestMicroservice</code> instance) based on the given module.
+    </td>
+  </tr>
+  <tr>
     <td>
       <code>get()</code>
     </td>
     <td>
       Retrieves a static instance of a controller or provider (including guards, filters, etc.) available in the application context. Inherited from the <a href="/fundamentals/module-ref">module reference</a> class.
     </td>
+  </tr>
   <tr>
      <td>
       <code>resolve()</code>

content/techniques/configuration.md

@@ -153,6 +153,26 @@ As shown above, use the `configService.get()` method to get a simple environment
 const dbHost = this.configService.get<string>('database.host', 'localhost');
 ```
 
+`ConfigService` has an optional generic (type argument) to help prevent accessing a config property that does not exist. Use it as shown below:
+
+```typescript
+interface EnvironmentVariables {
+  PORT: number;
+  TIMEOUT: string;
+}
+
+// somewhere in the code
+constructor(private configService: ConfigService<EnvironmentVariables>) {
+  // this is valid
+  const port = this.configService.get<number>('PORT');
+  
+  // this is invalid as URL is not a property on the EnvironmentVariables interface
+  const url = this.configService.get<string>('URL');
+}
+```
+
+> warning **Notice** If you have nested properties in your config, like in the `database.host` example above,  the interface must have a matching `'database.host': string;` property.  Otherwise a TypeScript error will be thrown.
+
 #### Configuration namespaces
 
 The `ConfigModule` allows you to define and load multiple custom configuration files, as shown in <a href="techniques/configuration#custom-configuration-files">Custom configuration files</a> above. You can manage complex configuration object hierarchies with nested configuration objects as shown in that section. Alternatively, you can return a "namespaced" configuration object with the `registerAs()` function as follows: