nx/packages/eslint-plugin-nx/src/rules/enforce-module-boundaries.ts

import { appRootPath } from '@nrwl/workspace/src/utils/app-root';
import {
  DepConstraint,
  findConstraintsFor,
  findProjectUsingImport,
  findSourceProject,
  getSourceFilePath,
  hasArchitectBuildBuilder,
  hasNoneOfTheseTags,
  isAbsoluteImportIntoAnotherProject,
  isCircular,
  isRelativeImportIntoAnotherProject,
  matchImportWithWildcard,
  onlyLoadChildren,
} from '@nrwl/workspace/src/utils/runtime-lint-utils';
import { TSESTree } from '@typescript-eslint/experimental-utils';
import { createESLintRule } from '../utils/create-eslint-rule';
import { normalize } from '@angular-devkit/core';
import {
  createProjectGraph,
  ProjectGraph,
  ProjectType,
} from '@nrwl/workspace/src/core/project-graph';
import {
  readNxJson,
  readWorkspaceJson,
} from '@nrwl/workspace/src/core/file-utils';
import { TargetProjectLocator } from '@nrwl/workspace/src/core/target-project-locator';

type Options = [
  {
    allow: string[];
    depConstraints: DepConstraint[];
    enforceBuildableLibDependency: boolean;
  }
];
export type MessageIds =
  | 'noRelativeOrAbsoluteImportsAcrossLibraries'
  | 'noCircularDependencies'
  | 'noImportsOfApps'
  | 'noImportOfNonBuildableLibraries'
  | 'noImportsOfLazyLoadedLibraries'
  | 'projectWithoutTagsCannotHaveDependencies'
  | 'tagConstraintViolation';
export const RULE_NAME = 'enforce-module-boundaries';

export default createESLintRule<Options, MessageIds>({
  name: RULE_NAME,
  meta: {
    type: 'suggestion',
    docs: {
      description: `Ensure that module boundaries are respected within the monorepo`,
      category: 'Best Practices',
      recommended: 'error',
    },
    fixable: 'code',
    schema: [
      {
        type: 'object',
        properties: {
          enforceBuildableLibDependency: { type: 'boolean' },
          allow: [{ type: 'string' }],
          depConstraints: [
            {
              type: 'object',
              properties: {
                sourceTag: { type: 'string' },
                onlyDependOnLibsWithTags: [{ type: 'string' }],
              },
              additionalProperties: false,
            },
          ],
        },
        additionalProperties: false,
      },
    ],
    messages: {
      noRelativeOrAbsoluteImportsAcrossLibraries: `Libraries cannot be imported by a relative or absolute path, and must begin with a npm scope`,
      noCircularDependencies: `Circular dependency between "{{sourceProjectName}}" and "{{targetProjectName}}" detected`,
      noImportsOfApps: 'Imports of apps are forbidden',
      noImportOfNonBuildableLibraries:
        'Buildable libraries cannot import non-buildable libraries',
      noImportsOfLazyLoadedLibraries: `Imports of lazy-loaded libraries are forbidden`,
      projectWithoutTagsCannotHaveDependencies: `A project without tags cannot depend on any libraries`,
      tagConstraintViolation: `A project tagged with "{{sourceTag}}" can only depend on libs tagged with {{allowedTags}}`,
    },
  },
  defaultOptions: [
    {
      allow: [],
      depConstraints: [],
      enforceBuildableLibDependency: false,
    },
  ],
  create(context, [{ allow, depConstraints, enforceBuildableLibDependency }]) {
    /**
     * Globally cached info about workspace
     */
    const projectPath = normalize((global as any).projectPath || appRootPath);
    if (!(global as any).projectGraph) {
      const workspaceJson = readWorkspaceJson();
      const nxJson = readNxJson();
      (global as any).npmScope = nxJson.npmScope;
      (global as any).projectGraph = createProjectGraph(workspaceJson, nxJson);
    }
    const npmScope = (global as any).npmScope;
    const projectGraph = (global as any).projectGraph as ProjectGraph;

    if (!(global as any).targetProjectLocator) {
      (global as any).targetProjectLocator = new TargetProjectLocator(
        projectGraph.nodes
      );
    }
    const targetProjectLocator = (global as any)
      .targetProjectLocator as TargetProjectLocator;

    return {
      ImportDeclaration(node: TSESTree.ImportDeclaration) {
        const imp = (node.source as TSESTree.Literal).value as string;

        const sourceFilePath = getSourceFilePath(
          normalize(context.getFilename()),
          projectPath
        );

        // whitelisted import
        if (allow.some((a) => matchImportWithWildcard(a, imp))) {
          return;
        }

        // check for relative and absolute imports
        if (
          isRelativeImportIntoAnotherProject(
            imp,
            projectPath,
            projectGraph,
            sourceFilePath
          ) ||
          isAbsoluteImportIntoAnotherProject(imp)
        ) {
          context.report({
            node,
            messageId: 'noRelativeOrAbsoluteImportsAcrossLibraries',
            data: {
              npmScope,
            },
          });
          return;
        }

        const sourceProject = findSourceProject(projectGraph, sourceFilePath);
        const targetProject = findProjectUsingImport(
          projectGraph,
          targetProjectLocator,
          sourceFilePath,
          imp,
          npmScope
        );

        // If source or target are not part of an nx workspace, return.
        if (!sourceProject || !targetProject) {
          return;
        }

        // same project => allow
        if (sourceProject === targetProject) {
          return;
        }

        // check constraints between libs and apps
        // check for circular dependency
        if (isCircular(projectGraph, sourceProject, targetProject)) {
          context.report({
            node,
            messageId: 'noCircularDependencies',
            data: {
              sourceProjectName: sourceProject.name,
              targetProjectName: targetProject.name,
            },
          });
          return;
        }

        // cannot import apps
        if (targetProject.type !== ProjectType.lib) {
          context.report({
            node,
            messageId: 'noImportsOfApps',
          });
          return;
        }

        // buildable-lib is not allowed to import non-buildable-lib
        if (
          enforceBuildableLibDependency === true &&
          sourceProject.type === ProjectType.lib &&
          targetProject.type === ProjectType.lib
        ) {
          if (
            hasArchitectBuildBuilder(sourceProject) &&
            !hasArchitectBuildBuilder(targetProject)
          ) {
            context.report({
              node,
              messageId: 'noImportOfNonBuildableLibraries',
            });
            return;
          }
        }

        // if we import a library using loadChildren, we should not import it using es6imports
        if (
          onlyLoadChildren(
            projectGraph,
            sourceProject.name,
            targetProject.name,
            []
          )
        ) {
          context.report({
            node,
            messageId: 'noImportsOfLazyLoadedLibraries',
          });
          return;
        }

        // check that dependency constraints are satisfied
        if (depConstraints.length > 0) {
          const constraints = findConstraintsFor(depConstraints, sourceProject);
          // when no constrains found => error. Force the user to provision them.
          if (constraints.length === 0) {
            context.report({
              node,
              messageId: 'projectWithoutTagsCannotHaveDependencies',
            });
            return;
          }

          for (let constraint of constraints) {
            if (
              hasNoneOfTheseTags(
                targetProject,
                constraint.onlyDependOnLibsWithTags || []
              )
            ) {
              const allowedTags = constraint.onlyDependOnLibsWithTags
                .map((s) => `"${s}"`)
                .join(', ');
              context.report({
                node,
                messageId: 'tagConstraintViolation',
                data: {
                  sourceTag: constraint.sourceTag,
                  allowedTags,
                },
              });
              return;
            }
          }
        }
      },
    };
  },
});