Fix false positive from no-internal-module on global augmentation

Fixes #1069

src/rules/noInternalModuleRule.ts

@@ -8,8 +8,7 @@
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
+
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
@@ -39,7 +38,8 @@ class NoInternalModuleWalker extends Lint.RuleWalker {
         // for external modules, node.name.kind will be a LiteralExpression instead of Identifier
         return !Lint.isNodeFlagSet(node, ts.NodeFlags.Namespace)
             && !isNestedDeclaration(node)
-            && node.name.kind === ts.SyntaxKind.Identifier;
+            && node.name.kind === ts.SyntaxKind.Identifier
+            && !isGlobalAugmentation(node);
     }
 }
 
@@ -49,3 +49,9 @@ function isNestedDeclaration(node: ts.ModuleDeclaration) {
     // nodes
     return node.name.pos === node.pos;
 }
+
+function isGlobalAugmentation(node: ts.ModuleDeclaration) {
+    // augmenting global uses a sepcial syntax that is allowed
+    // see https://github.com/Microsoft/TypeScript/pull/6213
+    return node.name.kind === ts.SyntaxKind.Identifier && node.name.text === "global";
+}

test/rules/no-internal-module/test.ts.lint

@@ -1,6 +1,9 @@
 namespace foo {
 }
 
+// valid, special syntax for augmenting global
+declare global { }
+
 module bar {
 ~~~~~~~~~~~~
 }