feat(schematics): add lint check for circular deps

packages/schematics/src/tslint/nxEnforceModuleBoundariesRule.spec.ts

@@ -321,6 +321,41 @@ describe('Enforce Module Boundaries', () => {
     );
     expect(failures[0].getFailure()).toEqual('imports of apps are forbidden');
   });
+
+  it('should error when circular dependency detected', () => {
+    const failures = runRule(
+      {},
+      `${process.cwd()}/proj/libs/anotherlib/src/main.ts`,
+      'import "@mycompany/mylib"',
+      [
+        {
+          name: 'mylib',
+          root: 'libs/mylib/src',
+          type: ProjectType.lib,
+          tags: [],
+          files: [`libs/mylib/src/main.ts`]
+        },
+        {
+          name: 'anotherlib',
+          root: 'libs/anotherlib/src',
+          type: ProjectType.lib,
+          tags: [],
+          files: [`libs/anotherlib/src/main.ts`]
+        },
+        {
+          name: 'myapp',
+          root: 'apps/myapp/src',
+          type: ProjectType.app,
+          tags: [],
+          files: [`apps/myapp/index.ts`]
+        }
+      ],
+      {
+        mylib: [{ projectName: 'anotherlib', type: DependencyType.es6Import }]
+      }
+    );
+    expect(failures[0].getFailure()).toEqual('Circular dependency between \"anotherlib\" and \"mylib\" detected');
+  });
 });
 
 function runRule(

packages/schematics/src/tslint/nxEnforceModuleBoundariesRule.ts

@@ -98,6 +98,13 @@ class EnforceModuleBoundariesWalker extends Lint.RuleWalker {
         return;
       }
 
+      // check for circular dependency
+      if (this.isCircular(sourceProject, targetProject)) {
+        const error = `Circular dependency between "${sourceProject.name}" and "${targetProject.name}" detected`;
+        this.addFailureAt(node.getStart(), node.getWidth(), error);
+        return;
+      }
+
       // same project => allow
       if (sourceProject === targetProject) {
         super.visitImportDeclaration(node);
@@ -146,6 +153,11 @@ class EnforceModuleBoundariesWalker extends Lint.RuleWalker {
     super.visitImportDeclaration(node);
   }
 
+  private isCircular(sourceProject: ProjectNode, targetProject: ProjectNode): boolean {
+    if (!this.deps[targetProject.name]) return false;
+    return this.deps[targetProject.name].some(dep => dep.projectName == sourceProject.name);
+  }
+
   private onlyLoadChildren(sourceProjectName: string, targetProjectName: string, visited: string[]) {
     if (visited.indexOf(sourceProjectName) > -1) return false;
     return (this.deps[sourceProjectName] || []).filter(d => {