diff --git a/Library/Homebrew/test/utils_spec.rb b/Library/Homebrew/test/utils_spec.rb
new file mode 100644
index 0000000000..c75d21bed8
--- /dev/null
+++ b/Library/Homebrew/test/utils_spec.rb
@@ -0,0 +1,61 @@
+# typed: false
+# frozen_string_literal: true
+
+require "utils"
+
+describe Utils do
+  describe ".deconstantize" do
+    it "removes the rightmost segment from the constant expression in the string" do
+      expect(described_class.deconstantize("Net::HTTP")).to eq("Net")
+      expect(described_class.deconstantize("::Net::HTTP")).to eq("::Net")
+      expect(described_class.deconstantize("String")).to eq("")
+      expect(described_class.deconstantize("::String")).to eq("")
+    end
+
+    it "returns an empty string if the namespace is empty" do
+      expect(described_class.deconstantize("")).to eq("")
+      expect(described_class.deconstantize("::")).to eq("")
+    end
+  end
+
+  describe ".demodulize" do
+    it "removes the module part from the expression in the string" do
+      expect(described_class.demodulize("Foo::Bar")).to eq("Bar")
+    end
+
+    it "returns the string if it does not contain a module expression" do
+      expect(described_class.demodulize("FooBar")).to eq("FooBar")
+    end
+
+    it "returns an empty string if the namespace is empty" do
+      expect(described_class.demodulize("")).to eq("")
+      expect(described_class.demodulize("::")).to eq("")
+    end
+  end
+
+  describe ".pluralize" do
+    it "combines the stem with the default suffix based on the count" do
+      expect(described_class.pluralize("foo", 0)).to eq("foos")
+      expect(described_class.pluralize("foo", 1)).to eq("foo")
+      expect(described_class.pluralize("foo", 2)).to eq("foos")
+    end
+
+    it "combines the stem with the singular suffix based on the count" do
+      expect(described_class.pluralize("foo", 0, singular: "o")).to eq("foos")
+      expect(described_class.pluralize("foo", 1, singular: "o")).to eq("fooo")
+      expect(described_class.pluralize("foo", 2, singular: "o")).to eq("foos")
+    end
+
+    it "combines the stem with the plural suffix based on the count" do
+      expect(described_class.pluralize("foo", 0, plural: "es")).to eq("fooes")
+      expect(described_class.pluralize("foo", 1, plural: "es")).to eq("foo")
+      expect(described_class.pluralize("foo", 2, plural: "es")).to eq("fooes")
+    end
+
+    it "combines the stem with the singular and plural suffix based on the count" do
+      expect(described_class.pluralize("foo", 0, singular: "o", plural: "es")).to eq("fooes")
+      expect(described_class.pluralize("foo", 1, singular: "o", plural: "es")).to eq("fooo")
+      expect(described_class.pluralize("foo", 2, singular: "o", plural: "es")).to eq("fooes")
+    end
+  end
+end