@W-16676971: drop support for Jest v.26 and v.27

.circleci/config.yml

@@ -1,6 +1,6 @@
 version: 2.1
 
-supported-jest-versions: &supported-jest-versions ["local", "26", "27", "28", "29"]
+supported-jest-versions: &supported-jest-versions ["local", "28", "29"]
 
 deploy_filters: &deploy_filters
   filters:
@@ -58,23 +58,11 @@ jobs:
               equal: [<<parameters.jest-version>>, "local"]
           steps:
             - run:
-                name: Override version of jest@<<parameters.jest-version>>
+                name: Override version of jest@<<parameters.jest-version>> and jest-environment-jsdom@<<parameters.jest-version>>
                 command: |
                   yarn remove jest jest-environment-jsdom -W --dev
                   yarn add jest@<<parameters.jest-version>> -W --dev
-            - when:
-                condition:
-                  equal: [<<parameters.jest-version>>, "26"]
-                steps:
-                  - run: yarn clean
-                  - run: yarn install
-            - when:
-                condition:
-                  or:
-                    - equal: [<<parameters.jest-version>>, "28"]
-                    - equal: [<<parameters.jest-version>>, "29"]
-                steps:
-                  - run: yarn add jest-environment-jsdom@<<parameters.jest-version>> -W --dev
+                  yarn add jest-environment-jsdom@<<parameters.jest-version>> -W --dev
       - run:
           name: Run linter
           command: yarn lint

packages/@lwc/jest-preset/package.json

@@ -28,7 +28,7 @@
         "@lwc/engine-dom": ">=5.0.0",
         "@lwc/engine-server": ">=5.0.0",
         "@lwc/synthetic-shadow": ">=5.0.0",
-        "jest": "^26 || ^27 || ^28 || ^29"
+        "jest": "^28 || ^29"
     },
     "dependencies": {
         "@lwc/jest-resolver": "16.1.0",

packages/@lwc/jest-preset/ssr/jest-preset.js

@@ -5,7 +5,6 @@
  * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
  */
 module.exports = {
-    // Jest 26 default testEnvironment is jsdom: https://jestjs.io/blog/2021/05/25/jest-27#flipping-defaults
     testEnvironment: 'node',
     moduleFileExtensions: ['ts', 'js', 'html'],
     snapshotSerializers: [require.resolve('../src/ssr/html-serializer.js')],

packages/@lwc/jest-resolver/package.json

@@ -25,7 +25,7 @@
         "@lwc/jest-shared": "16.1.0"
     },
     "peerDependencies": {
-        "jest": "^26 || ^27 || ^28 || ^29"
+        "jest": "^28 || ^29"
     },
     "engines": {
         "node": ">=10"

packages/@lwc/jest-serializer/package.json

@@ -22,7 +22,7 @@
         "pretty-format": "^29.7.0"
     },
     "peerDependencies": {
-        "jest": "^26 || ^27 || ^28 || ^29"
+        "jest": "^28 || ^29"
     },
     "engines": {
         "node": ">=10"

packages/@lwc/jest-transformer/package.json

@@ -35,7 +35,7 @@
     },
     "peerDependencies": {
         "@lwc/compiler": ">=2.48.0",
-        "jest": "^26 || ^27 || ^28 || ^29"
+        "jest": "^28 || ^29"
     },
     "engines": {
         "node": ">=10"

packages/@lwc/jest-transformer/src/index.js

@@ -168,11 +168,6 @@ module.exports = {
             // type getCacheKey = (sourceText: string, sourcePath: string, options: { configString: string }) => string;
             transformConfig = rest[0];
             configString = transformConfig.configString;
-        } else if (rest.length === 2) {
-            // Handle jest@26 arguments
-            // type getCacheKey = (sourceText: string, sourcePath: string, configStr: string, options: any) => string;
-            configString = rest[0];
-            transformConfig = rest[1];
         } else {
             throw new Error('Unexpected transform arguments.');
         }