test(tool): Add tests for CHANGELOG blank line validation

Adds unit tests to verify that the `version-check` command correctly fails when it detects blank lines between list items in a CHANGELOG, as this breaks list rendering on pub.dev.

Tests are added for both simple lists and nested lists. Also includes a minor formatting fix for the error message.

Signed-off-by: Lorenzo Croce <lorenzo.croce@arenastudios.it>

Author: Fireentity

script/tool/lib/src/version_check_command.dart

@@ -471,10 +471,10 @@ ${indentation}The first version listed in CHANGELOG.md is $fromChangeLog.
 
       printError(
           '${indentation}Blank lines found between list items in CHANGELOG.\n'
-              '${indentation}This creates multiple separate lists on pub.dev.\n'
-              '${indentation}Remove blank lines to keep all items in a single list.\n'
-              '${indentation}The problematic section found is:\n'
-              '$offendingLines');
+          '${indentation}This creates multiple separate lists on pub.dev.\n'
+          '${indentation}Remove blank lines to keep all items in a single list.\n'
+          '${indentation}The problematic section found is:\n'
+          '$offendingLines');
       return false;
     }
 

script/tool/test/version_check_command_test.dart

@@ -421,6 +421,83 @@ void main() {
       );
     });
 
+    test('Fail if CHANGELOG list items have a blank line', () async {
+      const String version = '1.0.1';
+      final RepositoryPackage plugin =
+      createFakePlugin('plugin', packagesDir, version: version);
+
+      // Blank line breaks the list items.
+      const String changelog = '''
+## $version
+* First item.
+
+* Second item.
+* Third item.
+''';
+      plugin.changelogFile.writeAsStringSync(changelog);
+      gitProcessRunner.mockProcessesForExecutable['git-show'] =
+      <FakeProcessInfo>[
+        FakeProcessInfo(MockProcess(stdout: 'version: 1.0.0')),
+      ];
+      Error? commandError;
+      final List<String> output = await runCapturingPrint(
+          runner, <String>['version-check', '--base-sha=main'],
+          errorHandler: (Error e) {
+            commandError = e;
+          });
+
+      expect(commandError, isA<ToolExit>());
+      expect(
+        output,
+        containsAllInOrder(<Matcher>[
+          contains('Running for plugin'),
+          contains('1.0.0 -> 1.0.1'),
+          contains('Blank lines found between list items in CHANGELOG.'),
+          contains('CHANGELOG.md failed validation.'),
+        ]),
+      );
+    });
+
+    test('Fail if CHANGELOG list items have a blank line with nested items',
+            () async {
+          const String version = '1.0.1';
+          final RepositoryPackage plugin =
+          createFakePlugin('plugin', packagesDir, version: version);
+
+          // Blank line in nested list items.
+          const String changelog = '''
+## $version
+* Top level item.
+  * Nested item A.
+  
+  * Nested item B.
+* Another top level item.
+''';
+          plugin.changelogFile.writeAsStringSync(changelog);
+          gitProcessRunner.mockProcessesForExecutable['git-show'] =
+          <FakeProcessInfo>[
+            FakeProcessInfo(MockProcess(stdout: 'version: 1.0.0')),
+          ];
+          Error? commandError;
+          final List<String> output = await runCapturingPrint(
+              runner, <String>['version-check', '--base-sha=main'],
+              errorHandler: (Error e) {
+                commandError = e;
+              });
+
+          expect(commandError, isA<ToolExit>());
+          expect(
+            output,
+            containsAllInOrder(<Matcher>[
+              contains('Running for plugin'),
+              contains('1.0.0 -> 1.0.1'),
+              contains('Blank lines found between list items in CHANGELOG.'),
+              contains('CHANGELOG.md failed validation.'),
+            ]),
+          );
+        });
+    // END OF NEW TESTS
+
     test(
         'Fail if pubspec version only matches an older version listed in CHANGELOG',
         () async {