feat: strongly typed property assertions

chaijs · Jan 1, 2024 · 015c19a · 015c19a
1 parent a0f959f
commit 015c19a
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Showing 3 changed files with 55 additions and 37 deletions.
diff --git a/src/chai/assertion.ts b/src/chai/assertion.ts
@@ -88,13 +88,13 @@ export class Assertion<T, TFlags extends AssertionFlags<T> = AssertionFlags<T>>
     util.flag(this, 'eql', config.deepEqual ?? util.eql);
   }
 
-  public static create<T>(
-    obj?: T,
+  public static create<TObj>(
+    obj?: TObj,
     msg?: string | null,
     ssfi?: Function,
     lockSsfi?: boolean
-  ): Assertion<T> {
-    return util.proxify(new Assertion<T>(
+  ): Assertion<TObj> {
+    return util.proxify(new Assertion<TObj>(
       obj,
       msg,
       ssfi,
@@ -131,7 +131,12 @@ export class Assertion<T, TFlags extends AssertionFlags<T> = AssertionFlags<T>>
   >(
     name: TKey,
     fn: TKey extends MethodNames<Assertion<unknown>> ?
-      (this: Assertion<unknown>, ...args: Parameters<Assertion<unknown>[TKey]>) => (ReturnType<Assertion<unknown>[TKey]> extends Assertion<unknown> ? (Assertion<unknown> | void) : ReturnType<Assertion<unknown>[TKey]>) :
+      (
+        this: Assertion<unknown>,
+        ...args: Parameters<Assertion<unknown>[TKey]>
+      ) => (
+        ReturnType<Assertion<unknown>[TKey]> | void
+      ) :
       ((this: Assertion<unknown>, ...args: never) => unknown)
   ): void {
     util.addMethod(this.prototype, name, fn, getDefaultValue);

diff --git a/src/chai/core/assertions.ts b/src/chai/core/assertions.ts
@@ -126,17 +126,21 @@ declare module '../assertion.js' {
     include: OnlyIf<T, CollectionLike<never> | string | object, ChainedMethod<T, TFlags, [val: unknown, msg?: string]>>;
     includes: OnlyIf<T, CollectionLike<never> | string | object, ChainedMethod<T, TFlags, [val: unknown, msg?: string]>>;
 
-    decrease: ((subject: Function) => Assertion<T, TFlags & {deltaBehavior: string}>) &
-      ((subject: object, prop: PropertyKey, msg?: string) => Assertion<T, TFlags & {deltaBehavior: string}>);
-    decreases: ((subject: Function) => Assertion<T, TFlags & {deltaBehavior: string}>) &
-      ((subject: object, prop: PropertyKey, msg?: string) => Assertion<T, TFlags & {deltaBehavior: string}>);
-
-    eq: (val: unknown, msg?: string) => Assertion<T, TFlags>;
-    equal: (val: unknown, msg?: string) => Assertion<T, TFlags>;
-    equals: (val: unknown, msg?: string) => Assertion<T, TFlags>;
-
-    eql: (val: unknown, msg?: string) => Assertion<T, TFlags>;
-    eqls: (val: unknown, msg?: string) => Assertion<T, TFlags>;
+    decrease: OnlyIf<T, Function, {
+      (subject: Function): Assertion<T, TFlags & {deltaBehavior: string}>;
+      (subject: object, prop: PropertyKey, msg?: string): Assertion<T, TFlags & {deltaBehavior: string}>;
+    }>;
+    decreases: OnlyIf<T, Function, {
+      (subject: Function): Assertion<T, TFlags & {deltaBehavior: string}>;
+      (subject: object, prop: PropertyKey, msg?: string): Assertion<T, TFlags & {deltaBehavior: string}>;
+    }>;
+
+    eq: (val: T, msg?: string) => Assertion<T, TFlags>;
+    equal: (val: T, msg?: string) => Assertion<T, TFlags>;
+    equals: (val: T, msg?: string) => Assertion<T, TFlags>;
+
+    eql: (val: T, msg?: string) => Assertion<T, TFlags>;
+    eqls: (val: T, msg?: string) => Assertion<T, TFlags>;
 
     greaterThanOrEqual: OnlyIf<
       T,
@@ -157,16 +161,28 @@ declare module '../assertion.js' {
       OnlyIf<TFlags, {doLength: true}, (val: number, msg?: string) => Assertion<T, TFlags>>
     >;
 
-    haveOwnProperty: (name: PropertyKey, val?: unknown, msg?: string) => Assertion<T, TFlags>;
-    ownProperty: (name: PropertyKey, val?: unknown, msg?: string) => Assertion<T, TFlags>;
-
-    haveOwnPropertyDescriptor: (name: PropertyKey, descriptor: PropertyDescriptor, msg?: string) => Assertion<T, TFlags>;
-    ownPropertyDescriptor: (name: PropertyKey, descriptor: PropertyDescriptor, msg?: string) => Assertion<T, TFlags>;
-
-    increase: ((subject: Function) => Assertion<T, TFlags & {deltaBehavior: string}>) &
-      ((subject: object, prop: PropertyKey, msg?: string) => Assertion<T, TFlags & {deltaBehavior: string}>);
-    increases: ((subject: Function) => Assertion<T, TFlags & {deltaBehavior: string}>) &
-      ((subject: object, prop: PropertyKey, msg?: string) => Assertion<T, TFlags & {deltaBehavior: string}>);
+    haveOwnProperty: OnlyIf<T, object, {
+      <TKey extends keyof T>(name: TKey): Assertion<T[TKey]>;
+      (name: PropertyKey): Assertion<unknown>;
+      <TKey extends keyof T>(name: TKey, val: T[TKey], msg?: string): Assertion<T[TKey]>;
+    }>;
+    ownProperty: OnlyIf<T, object, {
+      <TKey extends keyof T>(name: TKey): Assertion<T[TKey]>;
+      (name: PropertyKey): Assertion<unknown>;
+      <TKey extends keyof T>(name: TKey, val: T[TKey], msg?: string): Assertion<T[TKey]>;
+    }>;
+
+    haveOwnPropertyDescriptor: (name: PropertyKey, descriptor: PropertyDescriptor, msg?: string) => Assertion<PropertyDescriptor>;
+    ownPropertyDescriptor: (name: PropertyKey, descriptor: PropertyDescriptor, msg?: string) => Assertion<PropertyDescriptor>
+
+    increase: OnlyIf<T, Function, {
+      (subject: Function): Assertion<T, TFlags & {deltaBehavior: string}>;
+      (subject: object, prop: PropertyKey, msg?: string): Assertion<T, TFlags & {deltaBehavior: string}>;
+    }>;
+    increases: OnlyIf<T, Function, {
+      (subject: Function): Assertion<T, TFlags & {deltaBehavior: string}>;
+      (subject: object, prop: PropertyKey, msg?: string): Assertion<T, TFlags & {deltaBehavior: string}>;
+    }>;
 
     instanceOf: (ctor: Constructor<unknown>, msg?: string) => Assertion<T, TFlags>;
     instanceof: (ctor: Constructor<unknown>, msg?: string) => Assertion<T, TFlags>;
@@ -233,15 +249,12 @@ declare module '../assertion.js' {
     property: OnlyIf<T, object, OnlyIf<
       TFlags,
       {nested: true},
-      (name: string, val?: unknown, msg?: string) => Assertion<T, TFlags>,
-      OnlyIf<
-        [keyof T],
-        [never],
-        ((name: PropertyKey) => Assertion<T, TFlags>) &
-          ((name: PropertyKey, val: unknown, msg?: string) => Assertion<T, TFlags>),
-        ((name: PropertyKey) => Assertion<T, TFlags>) &
-          (<TKey extends keyof T>(name: TKey, val: T[TKey], msg?: string) => Assertion<T, TFlags>)
-      >
+      (name: string, val?: unknown, msg?: string) => Assertion<unknown, TFlags>,
+      {
+        <TKey extends keyof T>(name: TKey): Assertion<T[TKey]>;
+        (name: PropertyKey): Assertion<unknown>;
+        <TKey extends keyof T>(name: TKey, val: T[TKey], msg?: string): Assertion<T[TKey]>;
+      }
     >>;
 
     respondTo: (method: string, msg?: string) => Assertion<T, TFlags>;
@@ -809,7 +822,7 @@ function include<T>(this: Assertion<unknown>, val: T, msg?: string) {
         , numErrs = 0;
 
       props.forEach(function (this: Assertion<unknown>, prop) {
-        var propAssertion = Assertion.create(obj as object);
+        var propAssertion = Assertion.create(obj as Record<PropertyKey, unknown>);
         _.transferFlags(this, propAssertion, true);
         flag(propAssertion, 'lockSsfi', true);
 

diff --git a/src/chai/interface/assert.ts b/src/chai/interface/assert.ts
@@ -1671,7 +1671,7 @@ assert.notProperty = function (obj: object, prop: string, msg?: string) {
  * @api public
  */
 
-assert.propertyVal = function propertyVal<T, TKey extends keyof T>(obj: T, prop: TKey, val: T[TKey], msg?: string) {
+assert.propertyVal = function propertyVal<T extends object, TKey extends keyof T>(obj: T, prop: TKey, val: T[TKey], msg?: string) {
   Assertion.create(obj, msg, assert.propertyVal, true)
     .to.have.property(prop, val);
 };