Added istanbul rules to get 100% test coverage

src/common.ts

@@ -88,7 +88,7 @@ export const ownKeys: (target: AnyObject) => PropertyKey[] =
 				Object.getOwnPropertyNames(obj).concat(
 					Object.getOwnPropertySymbols(obj) as any
 				)
-		: Object.getOwnPropertyNames
+		: /* istanbul ignore next */ Object.getOwnPropertyNames
 
 export function each<T extends Objectish>(
 	obj: T,
@@ -108,6 +108,7 @@ export function isEnumerable(base: AnyObject, prop: PropertyKey): boolean {
 }
 
 export function getArchtype(thing: any): Archtype {
+	/* istanbul ignore next */
 	if (!thing) die()
 	if (thing[DRAFT_STATE]) {
 		switch ((thing as Drafted)[DRAFT_STATE].type) {
@@ -210,7 +211,7 @@ export function shallowCopy(base: any, invokeGetters = false) {
 	return clone
 }
 
-export function freeze(obj: any, deep: boolean = false): void {
+export function freeze(obj: any, deep: boolean): void {
 	if (!isDraftable(obj) || isDraft(obj) || Object.isFrozen(obj)) return
 	const type = getArchtype(obj)
 	if (type === Archtype.Set) {
@@ -238,6 +239,7 @@ export function createHiddenProperty(
 	})
 }
 
+/* istanbul ignore next */
 export function die(): never {
 	throw new Error("Illegal state, please file a bug")
 }

src/finalize.ts

@@ -78,17 +78,17 @@ function finalize(
 		finalizeTree(immer, state.draft, scope, path)
 
 		// We cannot really delete anything inside of a Set. We can only replace the whole Set.
-		if (immer.onDelete && !isSet(state.base)) {
+		if (immer.onDelete && state.type !== ProxyType.Set) {
 			// The `assigned` object is unreliable with ES5 drafts.
 			if (immer.useProxies) {
 				const {assigned} = state
 				each(assigned, (prop, exists) => {
-					if (!exists) immer.onDelete?.(state, prop as any)
+					if (!exists) immer.onDelete!(state, prop as any)
 				})
 			} else {
 				const {base, copy} = state
 				each(base, prop => {
-					if (!has(copy, prop)) immer.onDelete?.(state, prop as any)
+					if (!has(copy, prop)) immer.onDelete!(state, prop as any)
 				})
 			}
 		}

src/immer.ts

@@ -9,7 +9,8 @@ import {
 	isMap,
 	isDraftable,
 	DRAFT_STATE,
-	NOTHING
+	NOTHING,
+	die
 } from "./common"
 import {ImmerScope} from "./scope"
 import {
@@ -26,6 +27,7 @@ import {proxyMap} from "./map"
 import {proxySet} from "./set"
 import {processResult, maybeFreeze} from "./finalize"
 
+/* istanbul ignore next */
 function verifyMinified() {}
 
 const configDefaults = {
@@ -36,7 +38,8 @@ const configDefaults = {
 	autoFreeze:
 		typeof process !== "undefined"
 			? process.env.NODE_ENV !== "production"
-			: verifyMinified.name === "verifyMinified",
+			: /* istanbul ignore next */
+			  verifyMinified.name === "verifyMinified",
 	onAssign: null,
 	onDelete: null,
 	onCopy: null
@@ -163,8 +166,8 @@ export class Immer implements ProducersFns {
 				this.produceWithPatches(state, (draft: any) => arg1(draft, ...args))
 		}
 		// non-curried form
-		if (arg3)
-			throw new Error("A patch listener cannot be passed to produceWithPatches")
+		/* istanbul ignore next */
+		if (arg3) die()
 		let patches: Patch[], inversePatches: Patch[]
 		const nextState = this.produce(arg1, arg2, (p: Patch[], ip: Patch[]) => {
 			patches = p

src/map.ts

@@ -14,6 +14,7 @@ export interface MapState extends ImmerBaseState {
 }
 
 // Make sure DraftMap declarion doesn't die if Map is not avialable...
+/* istanbul ignore next */
 const MapBase: MapConstructor =
 	typeof Map !== "undefined" ? Map : (function FakeMap() {} as any)
 
@@ -117,6 +118,7 @@ export class DraftMap<K, V> extends MapBase implements Map<K, V> {
 			[iteratorSymbol]: () => this.values(),
 			next: () => {
 				const r = iterator.next()
+				/* istanbul ignore next */
 				if (r.done) return r
 				const value = this.get(r.value)
 				return {
@@ -133,6 +135,7 @@ export class DraftMap<K, V> extends MapBase implements Map<K, V> {
 			[iteratorSymbol]: () => this.entries(),
 			next: () => {
 				const r = iterator.next()
+				/* istanbul ignore next */
 				if (r.done) return r
 				const value = this.get(r.value)
 				return {

src/patches.ts

@@ -43,10 +43,11 @@ function generateArrayPatches(
 	inversePatches: Patch[]
 ) {
 	let {base, assigned, copy} = state
+	/* istanbul ignore next */
 	if (!copy) die()
 
 	// Reduce complexity by ensuring `base` is never longer.
-	if (copy!.length < base.length) {
+	if (copy.length < base.length) {
 		// @ts-ignore
 		;[base, copy] = [copy, base]
 		;[patches, inversePatches] = [inversePatches, patches]
@@ -173,6 +174,7 @@ export function applyPatches<T>(draft: T, patches: Patch[]): T {
 	patches.forEach(patch => {
 		const {path, op} = patch
 
+		/* istanbul ignore next */
 		if (!path.length) die()
 
 		let base: any = draft
@@ -190,6 +192,7 @@ export function applyPatches<T>(draft: T, patches: Patch[]): T {
 				switch (type) {
 					case Archtype.Map:
 						return base.set(key, value)
+					/* istanbul ignore next */
 					case Archtype.Set:
 						throw new Error('Sets cannot have "replace" patches.')
 					default:
@@ -199,7 +202,6 @@ export function applyPatches<T>(draft: T, patches: Patch[]): T {
 						// @ts-ignore
 						return (base[key] = value)
 				}
-				break
 			case "add":
 				switch (type) {
 					case Archtype.Array:

src/set.ts

@@ -14,6 +14,7 @@ export interface SetState extends ImmerBaseState {
 }
 
 // Make sure DraftSet declarion doesn't die if Map is not avialable...
+/* istanbul ignore next */
 const SetBase: SetConstructor =
 	typeof Set !== "undefined" ? Set : (function FakeSet() {} as any)
 
@@ -79,7 +80,7 @@ export class DraftSet<K, V> extends SetBase implements Set<V> {
 			state.copy!.delete(value) ||
 			(state.drafts.has(value)
 				? state.copy!.delete(state.drafts.get(value))
-				: false)
+				: /* istanbul ignore next */ false)
 		)
 	}