chore: enable unbound-method eslint rule (#33605)

Unbound method calls using `this` are likely to have unintended effects.

Here is an example with static methods, but the same thing applies to object methods:

```ts
class Class {
  public static staticMethod() {
    this.otherStaticMethod()
  }

  public static otherStaticMethod() { }
}

// ✅ valid
Class.staticMethod();

// ❌ boom
const x = Class.staticMethod;
x();
```

When assigning a method to a variable, you need to take extra care and this linter rule is going to remind you.

This rule also catches a lot of cases were we meant to call a function but accidentally didn't:

```ts
// Actual examples of unintentional code in our code base
list.map(x => x.toString).join(', ')

expect(x).toBeTruthy
```

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: rix0rrr

packages/@aws-cdk-testing/framework-integ/test/aws-appsync/test/integ.graphql.ts

@@ -178,12 +178,12 @@ customerDS.createResolver('MutationRemoveCustomer', {
   responseMappingTemplate: MappingTemplate.dynamoDbResultItem(),
 });
 
-const ops = [
-  { suffix: 'Eq', op: KeyCondition.eq },
-  { suffix: 'Lt', op: KeyCondition.lt },
-  { suffix: 'Le', op: KeyCondition.le },
-  { suffix: 'Gt', op: KeyCondition.gt },
-  { suffix: 'Ge', op: KeyCondition.ge },
+const ops: Array<{ suffix: string; op: (x: string, y: string) => KeyCondition }> = [
+  { suffix: 'Eq', op: (x, y) => KeyCondition.eq(x, y) },
+  { suffix: 'Lt', op: (x, y) => KeyCondition.lt(x, y) },
+  { suffix: 'Le', op: (x, y) => KeyCondition.le(x, y) },
+  { suffix: 'Gt', op: (x, y) => KeyCondition.gt(x, y) },
+  { suffix: 'Ge', op: (x, y) => KeyCondition.ge(x, y) },
 ];
 for (const { suffix, op } of ops) {
   orderDS.createResolver(`QueryGetCustomerOrders${suffix}`, {

packages/@aws-cdk/aws-eks-v2-alpha/lib/managed-nodegroup.ts

@@ -633,7 +633,7 @@ function getPossibleAmiTypes(instanceTypes: InstanceType[]): NodegroupAmiType[]
   const architectures: Set<AmiArchitecture> = new Set(instanceTypes.map(typeToArch));
 
   if (architectures.size === 0) { // protective code, the current implementation will never result in this.
-    throw new Error(`Cannot determine any ami type compatible with instance types: ${instanceTypes.map(i => i.toString).join(', ')}`);
+    throw new Error(`Cannot determine any ami type compatible with instance types: ${instanceTypes.map(i => i.toString()).join(', ')}`);
   }
 
   if (architectures.size > 1) {

packages/@aws-cdk/aws-glue-alpha/lib/triggers/workflow.ts

@@ -137,7 +137,7 @@ export abstract class WorkflowBase extends cdk.Resource implements IWorkflow {
       ...options,
       workflowName: this.workflowName,
       type: 'ON_DEMAND',
-      actions: options.actions?.map(this.renderAction),
+      actions: options.actions?.map(this.renderAction.bind(this)),
       description: options.description || undefined,
     });
 
@@ -162,7 +162,7 @@ export abstract class WorkflowBase extends cdk.Resource implements IWorkflow {
       ...options,
       workflowName: this.workflowName,
       type: 'SCHEDULED',
-      actions: options.actions?.map(this.renderAction),
+      actions: options.actions?.map(this.renderAction.bind(this)),
       schedule: dailySchedule.expressionString,
       startOnCreation: options.startOnCreation ?? false,
     });
@@ -189,7 +189,7 @@ export abstract class WorkflowBase extends cdk.Resource implements IWorkflow {
       ...options,
       workflowName: this.workflowName,
       type: 'SCHEDULED',
-      actions: options.actions?.map(this.renderAction),
+      actions: options.actions?.map(this.renderAction.bind(this)),
       schedule: weeklySchedule.expressionString,
       startOnCreation: options.startOnCreation ?? false,
     });
@@ -210,7 +210,7 @@ export abstract class WorkflowBase extends cdk.Resource implements IWorkflow {
       ...options,
       workflowName: this.workflowName,
       type: 'SCHEDULED',
-      actions: options.actions?.map(this.renderAction),
+      actions: options.actions?.map(this.renderAction.bind(this)),
       schedule: options.schedule.expressionString,
       startOnCreation: options.startOnCreation ?? false,
     });
@@ -231,7 +231,7 @@ export abstract class WorkflowBase extends cdk.Resource implements IWorkflow {
       ...options,
       workflowName: this.workflowName,
       type: 'EVENT',
-      actions: options.actions?.map(this.renderAction),
+      actions: options.actions?.map(this.renderAction.bind(this)),
       eventBatchingCondition: this.renderEventBatchingCondition(options),
       description: options.description ?? undefined,
     });
@@ -253,7 +253,7 @@ export abstract class WorkflowBase extends cdk.Resource implements IWorkflow {
       ...options,
       workflowName: this.workflowName,
       type: 'CONDITIONAL',
-      actions: options.actions?.map(this.renderAction),
+      actions: options.actions?.map(this.renderAction.bind(this)),
       predicate: this.renderPredicate(options),
       eventBatchingCondition: this.renderEventBatchingCondition(options),
       description: options.description ?? undefined,

packages/@aws-cdk/aws-iot-alpha/test/topic-rule.test.ts

@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/unbound-method */
 import { Template } from 'aws-cdk-lib/assertions';
 import * as cdk from 'aws-cdk-lib';
 import * as iot from '../lib';

packages/@aws-cdk/aws-kinesisanalytics-flink-alpha/test/application.test.ts

@@ -857,31 +857,31 @@ describe('Application', () => {
 
     // Table driven test with: [method, metricName, default statistic]
     const assertions: Array<[(options?: cloudwatch.MetricOptions) => cloudwatch.Metric, string, string]> = [
-      [flinkApp.metricKpus, 'KPUs', 'Average'],
-      [flinkApp.metricDowntime, 'downtime', 'Average'],
-      [flinkApp.metricUptime, 'uptime', 'Average'],
-      [flinkApp.metricFullRestarts, 'fullRestarts', 'Sum'],
-      [flinkApp.metricNumberOfFailedCheckpoints, 'numberOfFailedCheckpoints', 'Sum'],
-      [flinkApp.metricLastCheckpointDuration, 'lastCheckpointDuration', 'Maximum'],
-      [flinkApp.metricLastCheckpointSize, 'lastCheckpointSize', 'Maximum'],
-      [flinkApp.metricCpuUtilization, 'cpuUtilization', 'Average'],
-      [flinkApp.metricHeapMemoryUtilization, 'heapMemoryUtilization', 'Average'],
-      [flinkApp.metricOldGenerationGCTime, 'oldGenerationGCTime', 'Sum'],
-      [flinkApp.metricOldGenerationGCCount, 'oldGenerationGCCount', 'Sum'],
-      [flinkApp.metricThreadsCount, 'threadsCount', 'Average'],
-      [flinkApp.metricNumRecordsIn, 'numRecordsIn', 'Average'],
-      [flinkApp.metricNumRecordsInPerSecond, 'numRecordsInPerSecond', 'Average'],
-      [flinkApp.metricNumRecordsOut, 'numRecordsOut', 'Average'],
-      [flinkApp.metricNumRecordsOutPerSecond, 'numRecordsOutPerSecond', 'Average'],
-      [flinkApp.metricNumLateRecordsDropped, 'numLateRecordsDropped', 'Sum'],
-      [flinkApp.metricCurrentInputWatermark, 'currentInputWatermark', 'Maximum'],
-      [flinkApp.metricCurrentOutputWatermark, 'currentOutputWatermark', 'Maximum'],
-      [flinkApp.metricManagedMemoryUsed, 'managedMemoryUsed', 'Average'],
-      [flinkApp.metricManagedMemoryTotal, 'managedMemoryTotal', 'Average'],
-      [flinkApp.metricManagedMemoryUtilization, 'managedMemoryUtilization', 'Average'],
-      [flinkApp.metricIdleTimeMsPerSecond, 'idleTimeMsPerSecond', 'Average'],
-      [flinkApp.metricBackPressuredTimeMsPerSecond, 'backPressuredTimeMsPerSecond', 'Average'],
-      [flinkApp.metricBusyTimePerMsPerSecond, 'busyTimePerMsPerSecond', 'Average'],
+      [x => flinkApp.metricKpus(x), 'KPUs', 'Average'],
+      [x => flinkApp.metricDowntime(x), 'downtime', 'Average'],
+      [x => flinkApp.metricUptime(x), 'uptime', 'Average'],
+      [x => flinkApp.metricFullRestarts(x), 'fullRestarts', 'Sum'],
+      [x => flinkApp.metricNumberOfFailedCheckpoints(x), 'numberOfFailedCheckpoints', 'Sum'],
+      [x => flinkApp.metricLastCheckpointDuration(x), 'lastCheckpointDuration', 'Maximum'],
+      [x => flinkApp.metricLastCheckpointSize(x), 'lastCheckpointSize', 'Maximum'],
+      [x => flinkApp.metricCpuUtilization(x), 'cpuUtilization', 'Average'],
+      [x => flinkApp.metricHeapMemoryUtilization(x), 'heapMemoryUtilization', 'Average'],
+      [x => flinkApp.metricOldGenerationGCTime(x), 'oldGenerationGCTime', 'Sum'],
+      [x => flinkApp.metricOldGenerationGCCount(x), 'oldGenerationGCCount', 'Sum'],
+      [x => flinkApp.metricThreadsCount(x), 'threadsCount', 'Average'],
+      [x => flinkApp.metricNumRecordsIn(x), 'numRecordsIn', 'Average'],
+      [x => flinkApp.metricNumRecordsInPerSecond(x), 'numRecordsInPerSecond', 'Average'],
+      [x => flinkApp.metricNumRecordsOut(x), 'numRecordsOut', 'Average'],
+      [x => flinkApp.metricNumRecordsOutPerSecond(x), 'numRecordsOutPerSecond', 'Average'],
+      [x => flinkApp.metricNumLateRecordsDropped(x), 'numLateRecordsDropped', 'Sum'],
+      [x => flinkApp.metricCurrentInputWatermark(x), 'currentInputWatermark', 'Maximum'],
+      [x => flinkApp.metricCurrentOutputWatermark(x), 'currentOutputWatermark', 'Maximum'],
+      [x => flinkApp.metricManagedMemoryUsed(x), 'managedMemoryUsed', 'Average'],
+      [x => flinkApp.metricManagedMemoryTotal(x), 'managedMemoryTotal', 'Average'],
+      [x => flinkApp.metricManagedMemoryUtilization(x), 'managedMemoryUtilization', 'Average'],
+      [x => flinkApp.metricIdleTimeMsPerSecond(x), 'idleTimeMsPerSecond', 'Average'],
+      [x => flinkApp.metricBackPressuredTimeMsPerSecond(x), 'backPressuredTimeMsPerSecond', 'Average'],
+      [x => flinkApp.metricBusyTimePerMsPerSecond(x), 'busyTimePerMsPerSecond', 'Average'],
     ];
 
     assertions.forEach(([method, metricName, defaultStatistic]) => {

packages/@aws-cdk/aws-lambda-go-alpha/test/bundling.test.ts

@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/unbound-method */
 import * as child_process from 'child_process';
 import * as os from 'os';
 import * as path from 'path';

packages/@aws-cdk/aws-lambda-go-alpha/test/function.test.ts

@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/unbound-method */
 import * as path from 'path';
 import { Template } from 'aws-cdk-lib/assertions';
 import { Runtime } from 'aws-cdk-lib/aws-lambda';

packages/@aws-cdk/aws-lambda-python-alpha/test/bundling.test.ts

@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/unbound-method */
 import * as fs from 'fs';
 import * as path from 'path';
 import { Architecture, Code, Runtime } from 'aws-cdk-lib/aws-lambda';

packages/@aws-cdk/aws-lambda-python-alpha/test/function.test.ts

@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/unbound-method */
 import * as path from 'path';
 import { Template } from 'aws-cdk-lib/assertions';
 import { Code, Runtime, Architecture } from 'aws-cdk-lib/aws-lambda';

packages/@aws-cdk/aws-lambda-python-alpha/test/layer.test.ts

@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/unbound-method */
 import * as path from 'path';
 import { Runtime } from 'aws-cdk-lib/aws-lambda';
 import { DockerImage, Stack } from 'aws-cdk-lib';

packages/@aws-cdk/aws-pipes-alpha/test/pipe.test.ts

@@ -469,6 +469,7 @@ describe('Pipe', () => {
       expect(pipe.pipeRole).toBe(role);
       expect(source.grantRead).toHaveBeenCalledWith(role);
       expect(target.grantPush).toHaveBeenCalledWith(role);
+      // eslint-disable-next-line @typescript-eslint/unbound-method
       expect(enrichment.grantInvoke).toHaveBeenCalledWith(role);
     });
 

packages/@aws-cdk/integ-runner/test/workers/snapshot-worker.test.ts

@@ -1,4 +1,3 @@
-import * as child_process from 'child_process';
 import * as path from 'path';
 import * as fs from 'fs-extra';
 import { snapshotTestWorker } from '../../lib/workers/extract';
@@ -33,7 +32,6 @@ describe('Snapshot tests', () => {
 
   test('has snapshot', () => {
     // WHEN
-    jest.spyOn(child_process, 'spawnSync').mockResolvedValue;
     const test = {
       fileName: path.join(directory, 'xxxxx.test-with-snapshot.js'),
       discoveryRoot: directory,
@@ -46,7 +44,6 @@ describe('Snapshot tests', () => {
 
   test('failed snapshot', () => {
     // WHEN
-    jest.spyOn(child_process, 'spawnSync').mockRejectedValue;
     const test = {
       fileName: path.join(directory, 'xxxxx.test-with-snapshot-assets-diff.js'),
       discoveryRoot: directory,

packages/aws-cdk-lib/aws-backup/lib/plan.ts

@@ -200,7 +200,7 @@ export class BackupPlan extends Resource implements IBackupPlan {
     });
   }
 
-  private planCopyActions(props: BackupPlanCopyActionProps): CfnBackupPlan.CopyActionResourceTypeProperty {
+  private planCopyActions(this: void, props: BackupPlanCopyActionProps): CfnBackupPlan.CopyActionResourceTypeProperty {
     return {
       destinationBackupVaultArn: props.destinationBackupVault.backupVaultArn,
       lifecycle: (props.deleteAfter || props.moveToColdStorageAfter) && {

packages/aws-cdk-lib/aws-cloudfront/lib/geo-restriction.ts

@@ -11,7 +11,7 @@ export class GeoRestriction {
    * that you want to allow. Include one element for each country.
    * See ISO 3166-1-alpha-2 code on the *International Organization for Standardization* website
    */
-  public static allowlist(...locations: string[]) {
+  public static allowlist(this: void, ...locations: string[]) {
     return new GeoRestriction('whitelist', GeoRestriction.validateLocations(locations));
   }
 
@@ -22,7 +22,7 @@ export class GeoRestriction {
    * that you want to deny. Include one element for each country.
    * See ISO 3166-1-alpha-2 code on the *International Organization for Standardization* website
    */
-  public static denylist(...locations: string[]) {
+  public static denylist(this: void, ...locations: string[]) {
     return new GeoRestriction('blacklist', GeoRestriction.validateLocations(locations));
   }
 

packages/aws-cdk-lib/aws-config/lib/rule.ts

@@ -449,6 +449,7 @@ export class CustomRule extends RuleNew {
     }
     const hash = createHash('sha256')
       .update(JSON.stringify({
+        /* eslint-disable-next-line @typescript-eslint/unbound-method *//* REMOVEME: this is a latent bug */
         fnName: props.lambdaFunction.functionName.toString,
         accountId: Stack.of(this).resolve(this.env.account),
         region: Stack.of(this).resolve(this.env.region),

packages/aws-cdk-lib/aws-ec2/lib/cfn-init-elements.ts

@@ -655,42 +655,42 @@ export class InitPackage extends InitElement {
   /**
    * Install an RPM from an HTTP URL or a location on disk
    */
-  public static rpm(location: string, options: LocationPackageOptions = {}): InitPackage {
+  public static rpm(this: void, location: string, options: LocationPackageOptions = {}): InitPackage {
     return new InitPackage('rpm', [location], options.key, options.serviceRestartHandles);
   }
 
   /**
    * Install a package using Yum
    */
-  public static yum(packageName: string, options: NamedPackageOptions = {}): InitPackage {
+  public static yum(this: void, packageName: string, options: NamedPackageOptions = {}): InitPackage {
     return new InitPackage('yum', options.version ?? [], packageName, options.serviceRestartHandles);
   }
 
   /**
    * Install a package from RubyGems
    */
-  public static rubyGem(gemName: string, options: NamedPackageOptions = {}): InitPackage {
+  public static rubyGem(this: void, gemName: string, options: NamedPackageOptions = {}): InitPackage {
     return new InitPackage('rubygems', options.version ?? [], gemName, options.serviceRestartHandles);
   }
 
   /**
    * Install a package from PyPI
    */
-  public static python(packageName: string, options: NamedPackageOptions = {}): InitPackage {
+  public static python(this: void, packageName: string, options: NamedPackageOptions = {}): InitPackage {
     return new InitPackage('python', options.version ?? [], packageName, options.serviceRestartHandles);
   }
 
   /**
    * Install a package using APT
    */
-  public static apt(packageName: string, options: NamedPackageOptions = {}): InitPackage {
+  public static apt(this: void, packageName: string, options: NamedPackageOptions = {}): InitPackage {
     return new InitPackage('apt', options.version ?? [], packageName, options.serviceRestartHandles);
   }
 
   /**
    * Install an MSI package from an HTTP URL or a location on disk
    */
-  public static msi(location: string, options: LocationPackageOptions = {}): InitPackage {
+  public static msi(this: void, location: string, options: LocationPackageOptions = {}): InitPackage {
     // The MSI package version must be a string, not an array.
     return new class extends InitPackage {
       protected renderPackageVersions() { return location; }

packages/aws-cdk-lib/aws-ec2/test/ip-addresses.test.ts

@@ -12,12 +12,12 @@ describe('Cidr vpc allocation', () => {
 
   test('Default Cidr returns ipv4IpamPoolId as undefined', () => {
     const ipAddresses = IpAddresses.cidr('10.0.0.0/16');
-    expect(ipAddresses.allocateVpcCidr().ipv4IpamPoolId).toBeUndefined;
+    expect(ipAddresses.allocateVpcCidr().ipv4IpamPoolId).toBeUndefined();
   });
 
   test('Default Cidr returns ipv4NetmaskLength as undefined', () => {
     const ipAddresses = IpAddresses.cidr('10.0.0.0/16');
-    expect(ipAddresses.allocateVpcCidr().ipv4NetmaskLength).toBeUndefined;
+    expect(ipAddresses.allocateVpcCidr().ipv4NetmaskLength).toBeUndefined();
   });
 });
 
@@ -102,7 +102,7 @@ describe('AwsIpam vpc allocation', () => {
 
   test('AwsIpam returns cidrBlock as undefined', () => {
     const ipAddresses = IpAddresses.awsIpamAllocation(awsIpamProps);
-    expect(ipAddresses.allocateVpcCidr().cidrBlock).toBeUndefined;
+    expect(ipAddresses.allocateVpcCidr().cidrBlock).toBeUndefined();
   });
 
   test('AwsIpam returns the correct vpc ipv4IpamPoolId', () => {

packages/aws-cdk-lib/aws-ec2/test/vpc.from-lookup.test.ts

@@ -380,6 +380,7 @@ interface MockVpcContextResponse {
 function mockVpcContextProviderWith(
   response: MockVpcContextResponse,
   paramValidator?: (options: cxschema.VpcContextQuery) => void) {
+  // eslint-disable-next-line @typescript-eslint/unbound-method
   const previous = ContextProvider.getValue;
   ContextProvider.getValue = (_scope: Construct, options: GetContextValueOptions) => {
     // do some basic sanity checks

packages/aws-cdk-lib/aws-ecs-patterns/test/fargate/load-balanced-fargate-service.test.ts

@@ -710,7 +710,7 @@ describe('ApplicationLoadBalancedFargateService', () => {
     // THEN
     expect(() => {
       service.internalDesiredCount;
-    }).toBeTruthy;
+    }).toBeTruthy();
   });
 
   test('multiple capacity provider strategies are set', () => {

packages/aws-cdk-lib/aws-ecs/test/cluster.test.ts

@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/unbound-method */
 import { testDeprecated } from '@aws-cdk/cdk-build-tools';
 import { Annotations, Match, Template } from '../../assertions';
 import * as autoscaling from '../../aws-autoscaling';

packages/aws-cdk-lib/aws-ecs/test/fargate/fargate-task-definition.test.ts

@@ -352,7 +352,7 @@ describe('fargate task definition', () => {
       // THEN
       expect(() => {
         taskDefinition.ephemeralStorageGiB;
-      }).toBeTruthy;
+      }).toBeTruthy();
     });
 
     test('runtime testing for windows container', () => {

packages/aws-cdk-lib/aws-eks/lib/managed-nodegroup.ts

@@ -646,7 +646,7 @@ function getPossibleAmiTypes(instanceTypes: InstanceType[]): NodegroupAmiType[]
   const architectures: Set<AmiArchitecture> = new Set(instanceTypes.map(typeToArch));
 
   if (architectures.size === 0) { // protective code, the current implementation will never result in this.
-    throw new Error(`Cannot determine any ami type compatible with instance types: ${instanceTypes.map(i => i.toString).join(', ')}`);
+    throw new Error(`Cannot determine any ami type compatible with instance types: ${instanceTypes.map(i => i.toString()).join(', ')}`);
   }
 
   if (architectures.size > 1) {

packages/aws-cdk-lib/aws-elasticloadbalancingv2/lib/shared/listener-certificate.ts

@@ -17,14 +17,14 @@ export class ListenerCertificate implements IListenerCertificate {
   /**
    * Use an ACM certificate as a listener certificate
    */
-  public static fromCertificateManager(acmCertificate: acm.ICertificate) {
+  public static fromCertificateManager(this: void, acmCertificate: acm.ICertificate) {
     return new ListenerCertificate(acmCertificate.certificateArn);
   }
 
   /**
    * Use any certificate, identified by its ARN, as a listener certificate
    */
-  public static fromArn(certificateArn: string) {
+  public static fromArn(this: void, certificateArn: string) {
     return new ListenerCertificate(certificateArn);
   }
 

packages/aws-cdk-lib/aws-iam/lib/principals.ts

@@ -92,14 +92,14 @@ export class ComparablePrincipal {
   /**
    * Whether or not the given principal is a comparable principal
    */
-  public static isComparablePrincipal(x: IPrincipal): x is IComparablePrincipal {
+  public static isComparablePrincipal(this: void, x: IPrincipal): x is IComparablePrincipal {
     return 'dedupeString' in x;
   }
 
   /**
    * Return the dedupeString of the given principal, if available
    */
-  public static dedupeStringFor(x: IPrincipal): string | undefined {
+  public static dedupeStringFor(this: void, x: IPrincipal): string | undefined {
     return ComparablePrincipal.isComparablePrincipal(x) ? x.dedupeString() : undefined;
   }
 }