fix(awslint): Don't fail if the @aws-cdk/cdk module is not present (#…

…1953)

This simply means that no class may be a `Construct` or `Resource`, and
that is a pretty valid thing to have.

tools/awslint/lib/cfn-resources.ts

@@ -64,7 +64,11 @@ export function findCfnResources(assembly: reflect.Assembly): CfnResourceSpec[]
   }
 
   function isCfnResource(c: reflect.ClassType) {
-    const resourceBaseClass = c.system.findFqn('@aws-cdk/cdk.Resource');
+    const cdkAssembly = '@aws-cdk/cdk';
+    if (!c.system.includesAssembly(cdkAssembly)) {
+      return false;
+    }
+    const resourceBaseClass = c.system.findFqn(`${cdkAssembly}.Resource`);
 
     if (!isConstruct(c)) {
       return false;

tools/awslint/lib/util.ts

@@ -1,9 +1,13 @@
 import reflect = require('jsii-reflect');
 
-export const CONSTRUCT_FQN = '@aws-cdk/cdk.Construct';
-export const CONSTRUCT_INTERFACE_FQN = '@aws-cdk/cdk.IConstruct';
+export const CONSTRUCT_ASSEMBLY = '@aws-cdk/cdk';
+export const CONSTRUCT_FQN = `${CONSTRUCT_ASSEMBLY}.Construct`;
+export const CONSTRUCT_INTERFACE_FQN = `${CONSTRUCT_ASSEMBLY}.IConstruct`;
 
 export function isConstruct(c: reflect.ClassType) {
+  if (!c.system.includesAssembly(CONSTRUCT_ASSEMBLY)) {
+    return false;
+  }
   const constructClass = c.system.findFqn(CONSTRUCT_FQN);
   const bases = c.getAncestors();
   const root = bases[bases.length - 1];