refactor substitute core

Author: notanengineercom

src/Substitute.ts

@@ -1,49 +1,25 @@
-import { inspect, InspectOptions } from 'util'
+import { DisabledSubstituteObject, ObjectSubstitute } from './Transformations'
+import { SubstituteNode } from './SubstituteNode'
 
-import { SubstituteBase } from './SubstituteBase'
-import { createSubstituteProxy } from './SubstituteProxy'
-import { Recorder } from './Recorder'
-import { DisabledSubstituteObject, ObjectSubstitute, OmitProxyMethods } from './Transformations'
-
-export type SubstituteOf<T extends Object> = ObjectSubstitute<OmitProxyMethods<T>, T> & T
-type Instantiable<T> = { [SubstituteBase.instance]?: T }
-
-export class Substitute extends SubstituteBase {
-  private _proxy: Substitute
-  private _recorder: Recorder = new Recorder()
-  private _context: { disableAssertions: boolean } = { disableAssertions: false }
-
-  constructor() {
-    super()
-    this._proxy = createSubstituteProxy(
-      this,
-      {
-        get: (target, _property, _, node) => {
-          if (target.context.disableAssertions) node.disableAssertions()
-        }
-        // apply: (target, _, args, __, proxy) => {
-        // const rootProperty = proxy.get(target, '()', proxy) TODO: Implement to support callable interfaces
-        // return Reflect.apply(rootProperty, rootProperty, args)
-        // }
-      }
-    )
-  }
+export type SubstituteOf<T> = ObjectSubstitute<T> & T
+type InstantiableSubstitute = SubstituteOf<unknown> & { [SubstituteNode.instance]?: SubstituteNode }
 
+export class Substitute {
   static for<T>(): SubstituteOf<T> {
-    const substitute = new this()
+    const substitute = SubstituteNode.createRoot()
     return substitute.proxy as unknown as SubstituteOf<T>
   }
 
-  static disableFor<T extends SubstituteOf<unknown> & Instantiable<Substitute>>(substituteProxy: T): DisabledSubstituteObject<T> {
-    const substitute = substituteProxy[SubstituteBase.instance]
+  static disableFor<T extends InstantiableSubstitute>(substituteProxy: T): DisabledSubstituteObject<T> {
+    const substitute = substituteProxy[SubstituteNode.instance]
 
     const disableProxy = <
       TParameters extends unknown[],
       TReturnType extends unknown
     >(reflection: (...args: TParameters) => TReturnType): typeof reflection => (...args) => {
-      substitute.context.disableAssertions = true
+      substitute.rootContext.substituteMethodsEnabled = false
       const reflectionResult = reflection(...args)
-      substitute.context.disableAssertions = false
+      substitute.rootContext.substituteMethodsEnabled = true
       return reflectionResult
     }
 
@@ -59,23 +35,4 @@ export class Substitute extends SubstituteBase {
       }
     }) as DisabledSubstituteObject<T>
   }
-
-  public get proxy() {
-    return this._proxy
-  }
-
-  public get recorder() {
-    return this._recorder
-  }
-
-  public get context() {
-    return this._context
-  }
-
-  protected printableForm(_: number, options: InspectOptions): string {
-    const records = inspect(this.recorder, options)
-
-    const instanceName = 'Substitute' // Substitute<FooThing>
-    return instanceName + ' {' + records + '\n}'
-  }
 }

src/SubstituteBase.ts

@@ -1,53 +1,79 @@
-import { inspect, InspectOptions } from 'util'
+import { inspect, InspectOptions, types } from 'util'
 
-import { PropertyType, isSubstitutionMethod, isAssertionMethod, AssertionMethod, SubstitutionMethod, textModifier, ConfigurationMethod, isSubstituteMethod } from './Utilities'
-import { SubstituteException } from './SubstituteException'
-import { RecordedArguments } from './RecordedArguments'
 import { SubstituteNodeBase } from './SubstituteNodeBase'
-import { SubstituteBase } from './SubstituteBase'
-import { createSubstituteProxy } from './SubstituteProxy'
-import { ClearType } from './Transformations'
+import { RecordedArguments } from './RecordedArguments'
+import { ClearType as ClearTypeMap, PropertyType as PropertyTypeMap, isAssertionMethod, isSubstituteMethod, isSubstitutionMethod, textModifier } from './Utilities'
+import { SubstituteException } from './SubstituteException'
+import type { FilterFunction, SubstituteContext, SubstitutionMethod, ClearType, PropertyType } from './Types'
+
+const instance = Symbol('Substitute:Instance')
+type SpecialProperty = typeof instance | typeof inspect.custom | 'then'
+type RootContext = { substituteMethodsEnabled: boolean }
 
-type SubstituteContext = SubstitutionMethod | AssertionMethod | ConfigurationMethod | 'none'
-const clearTypeToFilterMap: Record<ClearType, (node: SubstituteNode) => boolean> = {
+const clearTypeToFilterMap: Record<ClearType, FilterFunction<SubstituteNode>> = {
   all: () => true,
   receivedCalls: node => !node.hasContext,
   substituteValues: node => node.isSubstitution
 }
 
-export class SubstituteNode extends SubstituteNodeBase<SubstituteNode> {
+export class SubstituteNode extends SubstituteNodeBase {
   private _proxy: SubstituteNode
-  private _propertyType: PropertyType = PropertyType.property
+  private _rootContext: RootContext
+
+  private _propertyType: PropertyType = PropertyTypeMap.Property
   private _accessorType: 'get' | 'set' = 'get'
   private _recordedArguments: RecordedArguments = RecordedArguments.none()
 
   private _context: SubstituteContext = 'none'
-  private _disabledAssertions: boolean = false
+  private _disabledSubstituteMethods: boolean = false
 
-  constructor(property: PropertyKey, parent: SubstituteNode | SubstituteBase) {
-    super(property, parent)
-    this._proxy = createSubstituteProxy(
+  private constructor(key: PropertyKey, parent?: SubstituteNode) {
+    super(key, parent)
+    if (this.isRoot()) this._rootContext = { substituteMethodsEnabled: true }
+    if (this.isIntermediateNode()) this._rootContext = this.root.rootContext
+    this._proxy = new Proxy(
       this,
       {
-        get: (node, _, __, nextNode) => {
-          if (node.isAssertion) nextNode.executeAssertion()
+        get: function (target, property) {
+          if (target.isSpecialProperty(property)) return target.evaluateSpecialProperty(property)
+          const newNode = SubstituteNode.createChild(property, target)
+          if (target.isRoot() && !target.rootContext.substituteMethodsEnabled) newNode.disableSubstituteMethods()
+          if (target.isIntermediateNode() && target.isAssertion) newNode.executeAssertion()
+          return newNode.read()
         },
-        set: (node, _, __, ___, nextNode) => {
-          if (node.isAssertion) nextNode.executeAssertion()
+        set: function (target, property, value) {
+          const newNode = SubstituteNode.createChild(property, target)
+          newNode.write(value)
+          if (target.isAssertion) newNode.executeAssertion()
+          return true
         },
-        apply: (node, _, rawArguments) => {
-          node.handleMethod(rawArguments)
-          if (node.context === 'clearSubstitute') return node.clear()
-          return node.parent?.isAssertion ?? false ? node.executeAssertion() : node.read()
+        apply: function (target, _thisArg, rawArguments) {
+          target.handleMethod(rawArguments)
+          if (target.hasContext) target.handleSpecialContext()
+          return (target.parent?.isAssertion ?? false) ? target.executeAssertion() : target.read()
         }
       }
     )
   }
 
+  public static instance: typeof instance = instance
+
+  public static createRoot(): SubstituteNode {
+    return new this('*Substitute<Root>')
+  }
+
+  public static createChild(key: PropertyKey, parent: SubstituteNode): SubstituteNode {
+    return new this(key, parent)
+  }
+
   public get proxy() {
     return this._proxy
   }
 
+  public get rootContext() {
+    return this._rootContext
+  }
+
   get context(): SubstituteContext {
     return this._context
   }
@@ -80,20 +106,20 @@ export class SubstituteNode extends SubstituteNodeBase<SubstituteNode> {
     return this._recordedArguments
   }
 
-  public get disabledAssertions() {
-    return this._disabledAssertions
+  public get disabledSubstituteMethods() {
+    return this._disabledSubstituteMethods
   }
 
   public assignContext(context: SubstituteContext): void {
     this._context = context
   }
 
-  public disableAssertions() {
-    this._disabledAssertions = true
+  public disableSubstituteMethods() {
+    this._disabledSubstituteMethods = true
   }
 
   public read(): SubstituteNode | void | never {
-    if (this.parent?.isSubstitution ?? false) return
+    if ((this.parent?.isSubstitution ?? false) || this.context === 'clearSubstitute') return
     if (this.isAssertion) return this.proxy
 
     const mostSuitableSubstitution = this.getMostSuitableSubstitution()
@@ -108,9 +134,9 @@ export class SubstituteNode extends SubstituteNodeBase<SubstituteNode> {
   }
 
   public clear() {
-    const clearType: ClearType = this.recordedArguments.value[0] ?? 'all'
-    const filter = clearTypeToFilterMap[clearType] as (node: SubstituteNodeBase) => boolean
-    this.root.recorder.clearRecords(filter)
+    const clearType: ClearType = this.recordedArguments.value[0] ?? ClearTypeMap.All
+    const filter = clearTypeToFilterMap[clearType]
+    this.recorder.clearRecords(filter)
   }
 
   public executeSubstitution(contextArguments: RecordedArguments) {
@@ -122,7 +148,7 @@ export class SubstituteNode extends SubstituteNodeBase<SubstituteNode> {
       case 'throws':
         throw substitutionValue
       case 'mimicks':
-        const argumentsToApply = this.propertyType === PropertyType.property ? [] : contextArguments.value
+        const argumentsToApply = this.propertyType === PropertyTypeMap.Property ? [] : contextArguments.value
         return substitutionValue(...argumentsToApply)
       case 'resolves':
         return Promise.resolve(substitutionValue)
@@ -136,8 +162,8 @@ export class SubstituteNode extends SubstituteNodeBase<SubstituteNode> {
   }
 
   public executeAssertion(): void | never {
-    const siblings = [...this.getAllSiblings().filter(n => !n.hasContext && n.accessorType === this.accessorType)]
     if (!this.isIntermediateNode()) throw new Error('Not possible')
+    const siblings = [...this.getAllSiblings().filter(n => !n.hasContext && n.accessorType === this.accessorType)]
 
     const expectedCount = this.parent.recordedArguments.value[0] ?? undefined
     const finiteExpectation = expectedCount !== undefined
@@ -168,14 +194,20 @@ export class SubstituteNode extends SubstituteNodeBase<SubstituteNode> {
   }
 
   public handleMethod(rawArguments: any[]): void {
-    this._propertyType = PropertyType.method
+    this._propertyType = PropertyTypeMap.Method
     this._recordedArguments = RecordedArguments.from(rawArguments)
-    if (!isSubstituteMethod(this.property)) return
+    this.tryToAssignContext()
+  }
 
+  private tryToAssignContext() {
+    if (!isSubstituteMethod(this.property)) return
     if (this.isIntermediateNode() && isSubstitutionMethod(this.property)) return this.parent.assignContext(this.property)
-    if (this.disabledAssertions || !this.isHead()) return
-
+    if (this.disabledSubstituteMethods) return
     this.assignContext(this.property)
+  }
+
+  private handleSpecialContext(): void {
+    if (this.context === 'clearSubstitute') return this.clear()
     if (this.context === 'didNotReceive') this._recordedArguments = RecordedArguments.from([0])
   }
 
@@ -188,7 +220,38 @@ export class SubstituteNode extends SubstituteNodeBase<SubstituteNode> {
     return sortedNodes[0]
   }
 
-  protected printableForm(_: number, options: InspectOptions): string {
+  private isSpecialProperty(property: PropertyKey): property is SpecialProperty {
+    return property === SubstituteNode.instance || property === inspect.custom || property === 'then'
+  }
+
+  private evaluateSpecialProperty(property: SpecialProperty) {
+    switch (property) {
+      case SubstituteNode.instance:
+        return this
+      case inspect.custom:
+        return this.printableForm.bind(this)
+      case 'then':
+        return
+      default:
+        throw SubstituteException.generic(`Evaluation of special property ${property} is not implemented`)
+    }
+  }
+
+  public [inspect.custom](...args: [_: number, options: InspectOptions]): string {
+    return types.isProxy(this) ? this[inspect.custom](...args) : this.printableForm(...args)
+  }
+
+  private printableForm(_: number, options: InspectOptions): string {
+    return this.isRoot() ? this.printRootNode(options) : this.printNode(options)
+  }
+
+  private printRootNode(options: InspectOptions): string {
+    const records = inspect(this.recorder, options)
+    const instanceName = '*Substitute<Root>' // Substitute<FooThing>
+    return instanceName + ' {' + records + '\n}'
+  }
+
+  private printNode(options: InspectOptions): string {
     const hasContext = this.hasContext
     const args = inspect(this.recordedArguments, options)
     const label = this.isSubstitution