Limit veclibfort & lapack cop to core & add tests

Library/Homebrew/rubocops/text.rb

@@ -17,7 +17,7 @@ module RuboCop
           end
 
           if depends_on?("veclibfort") || depends_on?("lapack")
-            problem "Formulae should use OpenBLAS as the default serial linear algebra library."
+            problem "Formulae should use OpenBLAS as the default serial linear algebra library." if formula_tap == "homebrew-core"
           end
 
           if method_called_ever?(body_node, :virtualenv_create) ||

Library/Homebrew/test/rubocops/text_spec.rb

@@ -32,6 +32,28 @@ describe RuboCop::Cop::FormulaAudit::Text do
       RUBY
     end
 
+    it "when veclibfort is used instead of OpenBLAS" do
+      expect_offense(<<~RUBY, "/homebrew-core/")
+        class Foo < Formula
+          url "https://brew.sh/foo-1.0.tgz"
+          homepage "https://brew.sh"
+          depends_on "veclibfort"
+          ^^^^^^^^^^^^^^^^^^^^^^^ Formulae should use OpenBLAS as the default serial linear algebra library.
+        end
+      RUBY
+    end
+
+    it "when lapack is used instead of OpenBLAS" do
+      expect_offense(<<~RUBY, "/homebrew-core/")
+        class Foo < Formula
+          url "https://brew.sh/foo-1.0.tgz"
+          homepage "https://brew.sh"
+          depends_on "lapack"
+          ^^^^^^^^^^^^^^^^^^^ Formulae should use OpenBLAS as the default serial linear algebra library.
+        end
+      RUBY
+    end
+
     it "When xcodebuild is called without SYMROOT" do
       expect_offense(<<~RUBY)
         class Foo < Formula