build: switch eslint-factory to use __testUtils__ instead of __tests__

Signed-off-by: MT Lewis <mtlewis@users.noreply.github.com>

.changeset/great-crews-own.md

@@ -2,13 +2,15 @@
 '@backstage/cli': minor
 ---
 
-Treat files in `__tests__` and `__mocks__` directories as test files for linting
+Treat files in `__testUtils__` and `__mocks__` directories as test files for linting
 purposes.
 
 Updates the parts of the eslint configuration generator that specify which files
-should be treated as test code to include any files under directories named
-`__tests__` or `__mocks__`, to match the default file locations used in Jest.
+should be treated as test code to include any files under two additional
+directories:
 
-cf.
-https://jestjs.io/docs/configuration/#testmatch-arraystring
-https://jestjs.io/docs/manual-mocks#mocking-user-modules
+- `__mocks__`: this is the directory used by Jest[0] for mock code.
+- `__testUtils__`: a suggested location for utility code executed only when
+  running tests.
+
+[0]: https://jestjs.io/docs/manual-mocks#mocking-user-modules

packages/cli/config/eslint-factory.js

@@ -96,7 +96,7 @@ function createConfig(dir, extraConfig = {}) {
                 `!${joinPath(dir, 'src/**')}`,
                 joinPath(dir, 'src/**/*.test.*'),
                 joinPath(dir, 'src/**/*.stories.*'),
-                joinPath(dir, 'src/**/__tests__/**'),
+                joinPath(dir, 'src/**/__testUtils__/**'),
                 joinPath(dir, 'src/**/__mocks__/**'),
                 joinPath(dir, 'src/setupTests.*'),
               ]
@@ -104,7 +104,7 @@ function createConfig(dir, extraConfig = {}) {
                 // Legacy config for packages that don't provide a dir
                 '**/*.test.*',
                 '**/*.stories.*',
-                '**/__tests__/**',
+                '**/__testUtils__/**',
                 '**/__mocks__/**',
                 '**/src/setupTests.*',
                 '**/dev/**',
@@ -141,7 +141,7 @@ function createConfig(dir, extraConfig = {}) {
             // Prevent imports of stories or tests
             '*.stories*',
             '*.test*',
-            '**/__tests__/**',
+            '**/__testUtils__/**',
             '**/__mocks__/**',
           ],
         },
@@ -168,7 +168,7 @@ function createConfig(dir, extraConfig = {}) {
         files: [
           '**/*.test.*',
           '**/*.stories.*',
-          '**/__tests__/**',
+          '**/__testUtils__/**',
           '**/__mocks__/**',
           'src/setupTests.*',
           '!src/**',