Make Homebrew::API::Versions#latest_cask_version tests macOS-only

Library/Homebrew/test/api/versions_spec.rb

@@ -4,30 +4,21 @@
 require "api"
 
 describe Homebrew::API::Versions do
-  let(:versions_formulae_json) {
-    <<~EOS
-      {
-        "foo":{"version":"1.2.3","revision":0},
-        "bar":{"version":"1.2","revision":4}
-      }
-    EOS
-  }
-  let(:versions_casks_json) {
-    <<~EOS
-      {
-        "foo":{"version":"1.2.3","versions":{}},
-        "bar":{"version":"1.2.3","versions":{"#{MacOS.version.to_sym}":"1.2.0"}},
-        "baz":{"version":"1.2.3","versions":{"test_os":"1.2.0"}}
-      }
-    EOS
-  }
-
   def mock_curl_output(stdout: "", success: true)
     curl_output = OpenStruct.new(stdout: stdout, success?: success)
     allow(Utils::Curl).to receive(:curl_output).and_return curl_output
   end
 
   describe "::latest_formula_version" do
+    let(:versions_formulae_json) {
+      <<~EOS
+        {
+          "foo":{"version":"1.2.3","revision":0},
+          "bar":{"version":"1.2","revision":4}
+        }
+      EOS
+    }
+
     it "returns the expected `PkgVersion` when the revision is 0" do
       mock_curl_output stdout: versions_formulae_json
       pkg_version = described_class.latest_formula_version("foo")
@@ -47,7 +38,17 @@ describe Homebrew::API::Versions do
     end
   end
 
-  describe "::latest_cask_version" do
+  describe "::latest_cask_version", :needs_macos do
+    let(:versions_casks_json) {
+      <<~EOS
+        {
+          "foo":{"version":"1.2.3","versions":{}},
+          "bar":{"version":"1.2.3","versions":{"#{MacOS.version.to_sym}":"1.2.0"}},
+          "baz":{"version":"1.2.3","versions":{"test_os":"1.2.0"}}
+        }
+      EOS
+    }
+
     it "returns the expected `Version`" do
       mock_curl_output stdout: versions_casks_json
       version = described_class.latest_cask_version("foo")