Better help message for --enforce-lock-file (#4421)

Author: sigurdm

lib/src/command/get.dart

@@ -38,7 +38,10 @@ class GetCommand extends PubCommand {
       'enforce-lockfile',
       negatable: false,
       help: 'Enforce pubspec.lock. '
-          'Fail resolution if pubspec.lock does not satisfy pubspec.yaml',
+          'Fail `pub get` if the current `pubspec.lock` '
+          'does not exactly specify a valid resolution of `pubspec.yaml` '
+          'or if any content hash of a hosted package has changed.\n'
+          'Useful for CI or deploying to production.',
     );
 
     argParser.addFlag(

test/testdata/goldens/help_test/pub get --help.txt

@@ -8,7 +8,9 @@ Usage: pub get
 -h, --help                Print this usage information.
     --[no-]offline        Use cached packages instead of accessing the network.
 -n, --dry-run             Report what dependencies would change but don't change any.
-    --enforce-lockfile    Enforce pubspec.lock. Fail resolution if pubspec.lock does not satisfy pubspec.yaml
+    --enforce-lockfile    Enforce pubspec.lock. Fail `pub get` if the current `pubspec.lock` does not exactly specify a valid resolution of `pubspec.yaml` or if any content hash of a hosted package
+                          has changed.
+                          Useful for CI or deploying to production.
     --[no-]precompile     Build executables in immediate dependencies.
 -C, --directory=<dir>     Run this in the directory <dir>.