api/spec/packages/aip/lib/rules/friendly-name.js

import { createRule, getFriendlyName, paramMessage } from '@typespec/compiler'

export const friendlyNameRule = createRule({
  name: 'friendly-name',
  severity: 'error',
  description: 'Ensure friendlyName decorator.',
  messages: {
    default: paramMessage`The ${'type'} ${'name'} must have a friendlyName decorator.`,
    avoid: paramMessage`The ${'type'} ${'name'} should not have a friendlyName decorator.`,
  },
  create: (context) => ({
    interface: (node) => {
      const hasFriendlyName = !!getFriendlyName(context.program, node)
      const isEndpointsOrOperations =
        node.name.endsWith('Endpoints') || node.name.endsWith('Operations')

      if (isEndpointsOrOperations && hasFriendlyName) {
        context.reportDiagnostic({
          format: {
            type: node.kind,
            name: node.name,
          },
          target: node,
          messageId: 'avoid',
        })
        return
      }

      if (!isEndpointsOrOperations && !hasFriendlyName) {
        context.reportDiagnostic({
          format: {
            type: node.kind,
            name: node.name,
          },
          target: node,
          messageId: 'default',
        })
      }
    },
    model: (node) => {
      if (node.name && !getFriendlyName(context.program, node)) {
        context.reportDiagnostic({
          format: {
            type: node.kind,
            name: node.name,
          },
          target: node,
          messageId: 'default',
        })
      }
    },
    enum: (node) => {
      if (node.name && !getFriendlyName(context.program, node)) {
        context.reportDiagnostic({
          format: {
            type: node.kind,
            name: node.name,
          },
          target: node,
          messageId: 'default',
        })
      }
    },
    union: (node) => {
      if (node.name && !getFriendlyName(context.program, node)) {
        context.reportDiagnostic({
          format: {
            type: node.kind,
            name: node.name,
          },
          target: node,
          messageId: 'default',
        })
      }
    },
  }),
})