Angular v12 - Unit Test - [ERROR] No specs found - unit-testing

Question

After developing my Angular application I would like to run unit tests with Karma and Jasmine.
I haven't written any unit-tests yet, but trying to run the default ones, with the 'ng test' command, I notice that the .spec files are not recognized by Karma-Jasmine.
Inside the browser, Karma gives the following message: "Incomplete, no specs found", in the terminal "Executed 0 of 0 SUCCESS".
I tried to generate a new application with the Angular CLI and to run the unit test. And it works.
Within my application, the Karma configuration files have not been touched, they are the same as those of the test application, and I don't understand why the .spec files are not recognized.
angular.json
{
"$schema": "./node_modules/#angular/cli/lib/config/schema.json",
"version": 1,
"newProjectRoot": "projects",
"projects": {
"dibfibo": {
"projectType": "application",
"schematics": {
"#schematics/angular:component": {
"style": "scss"
},
"#schematics/angular:application": {
"strict": true
}
},
"root": "",
"sourceRoot": "src",
"prefix": "app",
"architect": {
"build": {
"builder": "#angular-devkit/build-angular:browser",
"options": {
"outputPath": "dist/dibfibo",
"index": "src/index.html",
"main": "src/main.ts",
"polyfills": "src/polyfills.ts",
"tsConfig": "tsconfig.app.json",
"inlineStyleLanguage": "scss",
"assets": [
"src/favicon.ico",
"src/assets"
],
"styles": [
"src/styles.scss"
],
"scripts": []
},
"configurations": {
"production": {
"budgets": [
{
"type": "initial",
"maximumWarning": "500kb",
"maximumError": "1mb"
},
{
"type": "anyComponentStyle",
"maximumWarning": "2kb",
"maximumError": "4kb"
}
],
"fileReplacements": [
{
"replace": "src/environments/environment.ts",
"with": "src/environments/environment.prod.ts"
}
],
"outputHashing": "all"
},
"development": {
"buildOptimizer": false,
"optimization": false,
"vendorChunk": true,
"extractLicenses": false,
"sourceMap": true,
"namedChunks": true
}
},
"defaultConfiguration": "production"
},
"serve": {
"builder": "#angular-devkit/build-angular:dev-server",
"configurations": {
"production": {
"browserTarget": "dibfibo:build:production"
},
"development": {
"browserTarget": "dibfibo:build:development"
}
},
"defaultConfiguration": "development"
},
"extract-i18n": {
"builder": "#angular-devkit/build-angular:extract-i18n",
"options": {
"browserTarget": "dibfibo:build"
}
},
"test": {
"builder": "#angular-devkit/build-angular:karma",
"options": {
"main": "src/test.ts",
"polyfills": "src/polyfills.ts",
"tsConfig": "tsconfig.spec.json",
"karmaConfig": "karma.conf.js",
"inlineStyleLanguage": "scss",
"assets": [
"src/favicon.ico",
"src/assets"
],
"styles": [
"src/styles.scss"
],
"scripts": []
}
}
}
}
},
"defaultProject": "dibfibo"
}
karma.conf.js
// Karma configuration file, see link for more information
// https://karma-runner.github.io/1.0/config/configuration-file.html
module.exports = function (config) {
config.set({
basePath: '',
frameworks: ['jasmine', '#angular-devkit/build-angular'],
plugins: [
require('karma-jasmine'),
require('karma-chrome-launcher'),
require('karma-jasmine-html-reporter'),
require('karma-coverage'),
require('#angular-devkit/build-angular/plugins/karma')
],
client: {
jasmine: {
// you can add configuration options for Jasmine here
// the possible options are listed at https://jasmine.github.io/api/edge/Configuration.html
// for example, you can disable the random execution with `random: false`
// or set a specific seed with `seed: 4321`
},
clearContext: false // leave Jasmine Spec Runner output visible in browser
},
jasmineHtmlReporter: {
suppressAll: true // removes the duplicated traces
},
coverageReporter: {
dir: require('path').join(__dirname, './coverage/dibfibo'),
subdir: '.',
reporters: [
{ type: 'html' },
{ type: 'text-summary' }
]
},
reporters: ['progress', 'kjhtml'],
port: 9876,
colors: true,
logLevel: config.LOG_INFO,
autoWatch: true,
browsers: ['Chrome'],
singleRun: false,
restartOnFileChange: true
});
};