fix: #2138 linter issues with fail function (#2171)

* fix: #2138 linter issues with fail function

- refactoring fail function to be a custom Error class
- adjusting throw class given the above changes
- adding missing imports
- removing unused imports

* adding tests

* typo

__tests__/core/object.test.ts

@@ -21,6 +21,7 @@ import {
 } from "../../src"
 
 import { autorun, reaction, observable, configure, getDebugName } from "mobx"
+import { MstError } from "../../src/internal"
 
 const createTestFactories = () => {
   const Factory = types
@@ -887,7 +888,7 @@ test("#993-1 - after attach should have a parent when accesing a reference direc
     })
     .actions((self) => ({
       afterAttach() {
-        throw fail("should never be called")
+        throw new MstError("should never be called")
       }
     }))
 

__tests__/utils.test.ts

@@ -0,0 +1,20 @@
+import { MstError } from "../src/utils"
+
+describe("MstError custom error class", () => {
+  test("with default message", () => {
+    const error = new MstError()
+    expect(error.message).toBe("[mobx-state-tree] Illegal state")
+  })
+
+  test("with custom message", () => {
+    const customMessage = "custom error message"
+    const error = new MstError(customMessage)
+    expect(error.message).toBe(`[mobx-state-tree] ${customMessage}`)
+  })
+
+  test("instance of MstError", () => {
+    const error = new MstError()
+    expect(error).toBeInstanceOf(MstError)
+    expect(error).toBeInstanceOf(Error)
+  })
+})

src/core/action.ts

@@ -1,7 +1,7 @@
 import { action as mobxAction } from "mobx"
 import {
   getStateTreeNode,
-  fail,
+  MstError,
   argsToArray,
   IDisposer,
   getRoot,
@@ -292,12 +292,12 @@ function runMiddleWares(
     if (devMode()) {
       if (!nextInvoked && !abortInvoked) {
         const node2 = getStateTreeNode(call.tree)
-        throw fail(
+        throw new MstError(
           `Neither the next() nor the abort() callback within the middleware ${handler.name} for the action: "${call.name}" on the node: ${node2.type.name} was invoked.`
         )
       } else if (nextInvoked && abortInvoked) {
         const node2 = getStateTreeNode(call.tree)
-        throw fail(
+        throw new MstError(
           `The next() and abort() callback within the middleware ${handler.name} for the action: "${call.name}" on the node: ${node2.type.name} were invoked.`
         )
       }

src/core/flow.ts

@@ -1,4 +1,4 @@
-import { argsToArray, fail, setImmediateWithFallback } from "../utils"
+import { argsToArray, MstError, setImmediateWithFallback } from "../utils"
 import {
   FunctionWithFlag,
   getCurrentActionContext,
@@ -98,11 +98,11 @@ export function createFlowSpawner(name: string, generator: FunctionWithFlag) {
     const runId = getNextActionId()
     const parentContext = getCurrentActionContext()!
     if (!parentContext) {
-      throw fail("a mst flow must always have a parent context")
+      throw new MstError("a mst flow must always have a parent context")
     }
     const parentActionContext = getParentActionContext(parentContext)
     if (!parentActionContext) {
-      throw fail("a mst flow must always have a parent action context")
+      throw new MstError("a mst flow must always have a parent action context")
     }
 
     const contextBase = {
@@ -193,7 +193,7 @@ export function createFlowSpawner(name: string, generator: FunctionWithFlag) {
         // TODO: support more type of values? See https://github.com/tj/co/blob/249bbdc72da24ae44076afd716349d2089b31c4c/index.js#L100
         if (!ret.value || typeof ret.value.then !== "function") {
           // istanbul ignore next
-          throw fail("Only promises can be yielded to `async`, got: " + ret)
+          throw new MstError("Only promises can be yielded to `async`, got: " + ret)
         }
         return ret.value.then(onFulfilled, onRejected)
       }

src/core/json-patch.ts

@@ -1,4 +1,4 @@
-import { fail, stringStartsWith } from "../internal"
+import { MstError, stringStartsWith } from "../internal"
 
 /**
  * https://tools.ietf.org/html/rfc6902
@@ -19,7 +19,8 @@ export interface IReversibleJsonPatch extends IJsonPatch {
  * @hidden
  */
 export function splitPatch(patch: IReversibleJsonPatch): [IJsonPatch, IJsonPatch] {
-  if (!("oldValue" in patch)) throw fail(`Patches without \`oldValue\` field cannot be inversed`)
+  if (!("oldValue" in patch))
+    throw new MstError(`Patches without \`oldValue\` field cannot be inversed`)
   return [stripPatch(patch), invertPatch(patch)]
 }
 
@@ -127,7 +128,7 @@ export function splitJsonPath(path: string): string[] {
     stringStartsWith(path, "./") ||
     stringStartsWith(path, "../")
   if (!valid) {
-    throw fail(`a json path must be either rooted, empty or relative, but got '${path}'`)
+    throw new MstError(`a json path must be either rooted, empty or relative, but got '${path}'`)
   }
 
   // '/a/b/c' -> ["a", "b", "c"]

src/core/mst-operations.ts

@@ -10,7 +10,7 @@ import {
   splitJsonPath,
   asArray,
   EMPTY_OBJECT,
-  fail,
+  MstError,
   IDisposer,
   resolveNodeByPath,
   getRelativePathBetweenNodes,
@@ -268,7 +268,7 @@ export function protect(target: IAnyStateTreeNode): void {
   assertIsStateTreeNode(target, 1)
 
   const node = getStateTreeNode(target)
-  if (!node.isRoot) throw fail("`protect` can only be invoked on root nodes")
+  if (!node.isRoot) throw new MstError("`protect` can only be invoked on root nodes")
   node.isProtectionEnabled = true
 }
 
@@ -301,7 +301,7 @@ export function unprotect(target: IAnyStateTreeNode): void {
   assertIsStateTreeNode(target, 1)
 
   const node = getStateTreeNode(target)
-  if (!node.isRoot) throw fail("`unprotect` can only be invoked on root nodes")
+  if (!node.isRoot) throw new MstError("`unprotect` can only be invoked on root nodes")
   node.isProtectionEnabled = false
 }
 
@@ -394,7 +394,7 @@ export function getParent<IT extends IAnyStateTreeNode | IAnyComplexType>(
     if (--d === 0) return parent.storedValue as any
     parent = parent.parent
   }
-  throw fail(`Failed to find the parent of ${getStateTreeNode(target)} at depth ${depth}`)
+  throw new MstError(`Failed to find the parent of ${getStateTreeNode(target)} at depth ${depth}`)
 }
 
 /**
@@ -437,7 +437,7 @@ export function getParentOfType<IT extends IAnyComplexType>(
     if (type.is(parent.storedValue)) return parent.storedValue
     parent = parent.parent
   }
-  throw fail(`Failed to find the parent of ${getStateTreeNode(target)} of a given type`)
+  throw new MstError(`Failed to find the parent of ${getStateTreeNode(target)} of a given type`)
 }
 
 /**
@@ -577,7 +577,7 @@ export function tryReference<N extends IAnyStateTreeNode>(
         return isAlive(node) ? node : undefined
       }
     } else {
-      throw fail("The reference to be checked is not one of node, null or undefined")
+      throw new MstError("The reference to be checked is not one of node, null or undefined")
     }
   } catch (e) {
     if (e instanceof InvalidReferenceError) {
@@ -605,7 +605,7 @@ export function isValidReference<N extends IAnyStateTreeNode>(
     } else if (isStateTreeNode(node)) {
       return checkIfAlive ? isAlive(node) : true
     } else {
-      throw fail("The reference to be checked is not one of node, null or undefined")
+      throw new MstError("The reference to be checked is not one of node, null or undefined")
     }
   } catch (e) {
     if (e instanceof InvalidReferenceError) {
@@ -777,7 +777,7 @@ export function getEnv<T = any>(target: IAnyStateTreeNode): T {
 
   const node = getStateTreeNode(target)
   const env = node.root.environment
-  if (!env) throw fail(`Failed to find the environment of ${node} ${node.path}`)
+  if (!env) throw new MstError(`Failed to find the environment of ${node} ${node.path}`)
   return env
 }
 

src/core/node/BaseNode.ts

@@ -7,7 +7,7 @@ import {
   IAnyType,
   IDisposer,
   devMode,
-  fail
+  MstError
 } from "../../internal"
 import { createAtom, IAtom } from "mobx"
 
@@ -164,7 +164,9 @@ export abstract class BaseNode<C, S, T> {
     if (devMode()) {
       if (!this.isAlive) {
         // istanbul ignore next
-        throw fail("assertion failed: cannot finalize the creation of a node that is already dead")
+        throw new MstError(
+          "assertion failed: cannot finalize the creation of a node that is already dead"
+        )
       }
     }
 

src/core/node/create-node.ts

@@ -1,5 +1,5 @@
 import {
-  fail,
+  MstError,
   ObjectNode,
   ScalarNode,
   AnyNode,
@@ -24,7 +24,7 @@ export function createObjectNode<C, S, T>(
   if (existingNode) {
     if (existingNode.parent) {
       // istanbul ignore next
-      throw fail(
+      throw new MstError(
         `Cannot add an object to a state tree if it is already part of the same or another state tree. Tried to assign an object to '${
           parent ? parent.path : ""
         }/${subpath}', but it lives already at '${existingNode.path}'`

src/core/node/identifier-cache.ts

@@ -1,5 +1,5 @@
 import { IObservableArray, values, observable, entries } from "mobx"
-import { fail, ObjectNode, mobxShallow, AnyObjectNode, IAnyComplexType } from "../../internal"
+import { MstError, ObjectNode, mobxShallow, AnyObjectNode, IAnyComplexType } from "../../internal"
 
 let identifierCacheId = 0
 
@@ -37,7 +37,7 @@ export class IdentifierCache {
         this.cache.set(identifier, observable.array<AnyObjectNode>([], mobxShallow))
       }
       const set = this.cache.get(identifier)!
-      if (set.indexOf(node) !== -1) throw fail(`Already registered`)
+      if (set.indexOf(node) !== -1) throw new MstError(`Already registered`)
       set.push(node)
       if (lastCacheUpdate) {
         this.updateLastCacheModificationPerId(identifier)
@@ -114,7 +114,7 @@ export class IdentifierCache {
       case 1:
         return matches[0]
       default:
-        throw fail(
+        throw new MstError(
           `Cannot resolve a reference to type '${
             type.name
           }' with id: '${identifier}' unambigously, there are multiple candidates: ${matches

src/core/node/node-utils.ts

@@ -1,5 +1,5 @@
 import {
-  fail,
+  MstError,
   ObjectNode,
   splitJsonPath,
   joinJsonPath,
@@ -89,7 +89,7 @@ export function assertIsStateTreeNode(
 export function getStateTreeNode(value: IAnyStateTreeNode): AnyObjectNode {
   if (!isStateTreeNode(value)) {
     // istanbul ignore next
-    throw fail(`Value ${value} is no MST Node`)
+    throw new MstError(`Value ${value} is no MST Node`)
   }
   return value.$treenode!
 }
@@ -119,7 +119,7 @@ const doubleDot = (_: any) => ".."
 export function getRelativePathBetweenNodes(base: AnyObjectNode, target: AnyObjectNode): string {
   // PRE condition target is (a child of) base!
   if (base.root !== target.root) {
-    throw fail(
+    throw new MstError(
       `Cannot calculate relative path: objects '${base}' and '${target}' are not part of the same object tree`
     )
   }
@@ -182,7 +182,7 @@ export function resolveNodeByPathParts(
           }
         }
       }
-      throw fail(
+      throw new MstError(
         `Could not resolve '${part}' in path '${
           joinJsonPath(pathParts.slice(0, i)) || "/"
         }' while resolving '${joinJsonPath(pathParts)}'`

src/core/node/object-node.ts

@@ -7,7 +7,7 @@ import {
   createActionInvoker,
   EMPTY_OBJECT,
   extend,
-  fail,
+  MstError,
   freeze,
   IAnyType,
   IdentifierCache,
@@ -155,7 +155,7 @@ export class ObjectNode<C, S, T> extends BaseNode<C, S, T> {
       }
 
       if (typeof id !== "string" && typeof id !== "number") {
-        throw fail(
+        throw new MstError(
           `Instance identifier '${this.identifierAttribute}' for type '${this.type.name}' must be a string or a number`
         )
       }
@@ -182,7 +182,7 @@ export class ObjectNode<C, S, T> extends BaseNode<C, S, T> {
     if (devMode()) {
       if (this.state !== NodeLifeCycle.INITIALIZING) {
         // istanbul ignore next
-        throw fail(
+        throw new MstError(
           "assertion failed: the creation of the observable instance must be done on the initializing phase"
         )
       }
@@ -294,25 +294,25 @@ export class ObjectNode<C, S, T> extends BaseNode<C, S, T> {
     if (devMode()) {
       if (!subpath) {
         // istanbul ignore next
-        throw fail("assertion failed: subpath expected")
+        throw new MstError("assertion failed: subpath expected")
       }
       if (!newParent) {
         // istanbul ignore next
-        throw fail("assertion failed: new parent expected")
+        throw new MstError("assertion failed: new parent expected")
       }
 
       if (this.parent && parentChanged) {
-        throw fail(
+        throw new MstError(
           `A node cannot exists twice in the state tree. Failed to add ${this} to path '${newParent.path}/${subpath}'.`
         )
       }
       if (!this.parent && newParent.root === this) {
-        throw fail(
+        throw new MstError(
           `A state tree is not allowed to contain itself. Cannot assign ${this} to path '${newParent.path}/${subpath}'`
         )
       }
       if (!this.parent && !!this.environment && this.environment !== newParent.root.environment) {
-        throw fail(
+        throw new MstError(
           `A state tree cannot be made part of another state tree as long as their environments are different.`
         )
       }
@@ -394,7 +394,7 @@ export class ObjectNode<C, S, T> extends BaseNode<C, S, T> {
       const error = this._getAssertAliveError(context)
       switch (livelinessChecking) {
         case "error":
-          throw fail(error)
+          throw new MstError(error)
         case "warn":
           warnError(error)
       }
@@ -460,7 +460,7 @@ export class ObjectNode<C, S, T> extends BaseNode<C, S, T> {
   assertWritable(context: AssertAliveContext): void {
     this.assertAlive(context)
     if (!this.isRunningAction() && this.isProtected) {
-      throw fail(
+      throw new MstError(
         `Cannot modify '${this}', the object is protected and can only be modified by using an action.`
       )
     }
@@ -497,7 +497,7 @@ export class ObjectNode<C, S, T> extends BaseNode<C, S, T> {
   }
 
   detach(): void {
-    if (!this.isAlive) throw fail(`Error while detaching, node is not alive.`)
+    if (!this.isAlive) throw new MstError(`Error while detaching, node is not alive.`)
 
     this.clearParent()
   }
@@ -607,12 +607,12 @@ export class ObjectNode<C, S, T> extends BaseNode<C, S, T> {
       this._internalEventsRegister(InternalEvents.Dispose, disposer, true)
       return
     }
-    throw fail("cannot add a disposer when it is already registered for execution")
+    throw new MstError("cannot add a disposer when it is already registered for execution")
   }
 
   removeDisposer(disposer: () => void): void {
     if (!this._internalEventsHas(InternalEvents.Dispose, disposer)) {
-      throw fail("cannot remove a disposer which was never registered for execution")
+      throw new MstError("cannot remove a disposer which was never registered for execution")
     }
     this._internalEventsUnregister(InternalEvents.Dispose, disposer)
   }