test fix

Author: chika3742

lib/src/solver/version_solver.dart

@@ -396,23 +396,39 @@ class VersionSolver {
       return null; // when unsatisfied.isEmpty
     }
 
-    bool isDirectAndStable(String packageName) {
-      final dep = _root.pubspec.dependencies[packageName];
-      if (dep == null) return false; // not a direct dependency
-      final constraint = dep.constraint;
-      if (constraint is Version) {
-        return !constraint.isPreRelease;
+    // Prereleases are allowed only if the dependency is transitive, or if
+    // the constraint explicitly allows prereleases.
+    bool shouldAllowPrereleases(String packageName) {
+      final workspaces = [_root, ..._root.workspaceChildren];
+      bool constraintContainsPrerelease(VersionConstraint? constraint) {
+        if (constraint is Version) {
+          return constraint.isPreRelease;
+        }
+        if (constraint is VersionRange) {
+          return (constraint.min != null && constraint.min!.isPreRelease) ||
+                 (constraint.max != null && constraint.max!.isPreRelease) ||
+                 constraint.isAny;
+        }
+        return false;
       }
-      if (constraint is VersionRange && constraint.min != null) {
-        return !constraint.min!.isPreRelease;
+      var isDirectOrDev = false;
+      for (final workspace in workspaces) {
+        final directDep = workspace.dependencies[packageName];
+        if (directDep != null && constraintContainsPrerelease(directDep.constraint)) {
+          return true;
+        }
+        final devDep = workspace.devDependencies[packageName];
+        if (devDep != null && constraintContainsPrerelease(devDep.constraint)) {
+          return true;
+        }
+        isDirectOrDev = isDirectOrDev || directDep != null || devDep != null;
       }
-      return false;
+      return !isDirectOrDev;
     }
 
     PackageId? version;
     try {
-      // Prereleases are allowed only if not direct or not stable.
-      final allowPrereleases = !isDirectAndStable(package.name);
+      final allowPrereleases = shouldAllowPrereleases(package.name);
       version = await _packageLister(
         package,
       ).bestVersion(package.constraint, allowPrereleases: allowPrereleases);