MacOSVersion: expand test coverage

This adds tests to expand coverage of `MacOSVersion` to 100% for lines
and branches.

Library/Homebrew/test/macos_version_spec.rb

@@ -4,12 +4,15 @@ require "macos_version"
 
 RSpec.describe MacOSVersion do
   let(:version) { described_class.new("10.14") }
+  let(:tahoe_major) { described_class.new("26.0") }
   let(:big_sur_major) { described_class.new("11.0") }
   let(:big_sur_update) { described_class.new("11.1") }
+  let(:frozen_version) { described_class.new("10.14").freeze }
 
-  describe ".kernel_major_version" do
+  describe "::kernel_major_version" do
     it "returns the kernel major version" do
       expect(described_class.kernel_major_version(version)).to eq "18"
+      expect(described_class.kernel_major_version(tahoe_major)).to eq "25"
       expect(described_class.kernel_major_version(big_sur_major)).to eq "20"
       expect(described_class.kernel_major_version(big_sur_update)).to eq "20"
     end
@@ -19,12 +22,43 @@ RSpec.describe MacOSVersion do
     end
   end
 
+  describe "::from_symbol" do
+    it "raises an error if the symbol is not a valid macOS version" do
+      expect do
+        described_class.from_symbol(:foo)
+      end.to raise_error(MacOSVersion::Error, "unknown or unsupported macOS version: :foo")
+    end
+
+    it "creates a new version from a valid macOS version" do
+      symbol_version = described_class.from_symbol(:mojave)
+      expect(symbol_version).to eq(version)
+    end
+  end
+
+  describe "#new" do
+    it "raises an error if the version is not a valid macOS version" do
+      expect do
+        described_class.new("1.2")
+      end.to raise_error(MacOSVersion::Error, 'unknown or unsupported macOS version: "1.2"')
+    end
+
+    it "creates a new version from a valid macOS version" do
+      string_version = described_class.new("11")
+      expect(string_version).to eq(:big_sur)
+    end
+  end
+
   specify "comparison with Symbol" do
     expect(version).to be > :high_sierra
     expect(version).to eq :mojave
     # We're explicitly testing the `===` operator results here.
     expect(version).to be === :mojave # rubocop:disable Style/CaseEquality
     expect(version).to be < :catalina
+
+    # This should work like a normal comparison but the result won't be added
+    # to the `@comparison_cache` hash because the object is frozen.
+    expect(frozen_version).to eq :mojave
+    expect(frozen_version.instance_variable_get(:@comparison_cache)).to eq({})
   end
 
   specify "comparison with Integer" do
@@ -64,44 +98,90 @@ RSpec.describe MacOSVersion do
     end
   end
 
-  describe "#new" do
-    it "raises an error if the version is not a valid macOS version" do
-      expect do
-        described_class.new("1.2")
-      end.to raise_error(MacOSVersion::Error, 'unknown or unsupported macOS version: "1.2"')
+  describe "#strip_patch" do
+    let(:catalina_update) { described_class.new("10.15.1") }
+
+    it "returns the version without the patch" do
+      expect(big_sur_update.strip_patch).to eq(described_class.new("11"))
+      expect(catalina_update.strip_patch).to eq(described_class.new("10.15"))
     end
 
-    it "creates a new version from a valid macOS version" do
-      string_version = described_class.new("11")
-      expect(string_version).to eq(:big_sur)
+    it "returns self if version is null" do
+      expect(described_class::NULL.strip_patch).to be described_class::NULL
     end
   end
 
-  describe "#from_symbol" do
-    it "raises an error if the symbol is not a valid macOS version" do
-      expect do
-        described_class.from_symbol(:foo)
-      end.to raise_error(MacOSVersion::Error, "unknown or unsupported macOS version: :foo")
-    end
+  specify "#to_sym" do
+    version_symbol = :mojave
 
-    it "creates a new version from a valid macOS version" do
-      symbol_version = described_class.from_symbol(:mojave)
-      expect(symbol_version).to eq(version)
-    end
+    # We call this more than once to exercise the caching logic
+    expect(version.to_sym).to eq(version_symbol)
+    expect(version.to_sym).to eq(version_symbol)
+
+    # This should work like a normal but the symbol won't be stored as the
+    # `@sym` instance variable because the object is frozen.
+    expect(frozen_version.to_sym).to eq(version_symbol)
+    expect(frozen_version.instance_variable_get(:@sym)).to be_nil
+
+    expect(described_class::NULL.to_sym).to eq(:dunno)
   end
 
   specify "#pretty_name" do
+    version_pretty_name = "Mojave"
+
     expect(described_class.new("10.11").pretty_name).to eq("El Capitan")
-    expect(described_class.new("10.14").pretty_name).to eq("Mojave")
+
+    # We call this more than once to exercise the caching logic
+    expect(version.pretty_name).to eq(version_pretty_name)
+    expect(version.pretty_name).to eq(version_pretty_name)
+
+    # This should work like a normal but the computed name won't be stored as
+    # the `@pretty_name` instance variable because the object is frozen.
+    expect(frozen_version.pretty_name).to eq(version_pretty_name)
+    expect(frozen_version.instance_variable_get(:@pretty_name)).to be_nil
   end
 
   specify "#inspect" do
     expect(described_class.new("11").inspect).to eq("#<MacOSVersion: \"11\">")
   end
 
-  specify "#requires_nehalem_cpu?", :needs_macos do
-    expect(Hardware::CPU).to receive(:type).at_least(:twice).and_return(:intel)
-    expect(described_class.new("10.14").requires_nehalem_cpu?).to be true
-    expect(described_class.new("10.12").requires_nehalem_cpu?).to be false
+  specify "#outdated_release?" do
+    expect(described_class.new(described_class::SYMBOLS.values.first).outdated_release?).to be false
+    expect(described_class.new("10.0").outdated_release?).to be true
+  end
+
+  specify "#prerelease?" do
+    expect(described_class.new("1000").prerelease?).to be true
+  end
+
+  specify "#unsupported_release?" do
+    expect(described_class.new("10.0").unsupported_release?).to be true
+    expect(described_class.new("1000").prerelease?).to be true
+  end
+
+  describe "#requires_nehalem_cpu?", :needs_macos do
+    context "when CPU is Intel" do
+      it "returns true if version requires a Nehalem CPU" do
+        allow(Hardware::CPU).to receive(:type).and_return(:intel)
+        expect(described_class.new("10.14").requires_nehalem_cpu?).to be true
+      end
+
+      it "returns false if version does not require a Nehalem CPU" do
+        allow(Hardware::CPU).to receive(:type).and_return(:intel)
+        expect(described_class.new("10.12").requires_nehalem_cpu?).to be false
+      end
+    end
+
+    context "when CPU is not Intel" do
+      it "raises an error" do
+        allow(Hardware::CPU).to receive(:type).and_return(:arm)
+        expect { described_class.new("10.14").requires_nehalem_cpu? }
+          .to raise_error(ArgumentError)
+      end
+    end
+
+    it "returns false when version is null" do
+      expect(described_class::NULL.requires_nehalem_cpu?).to be false
+    end
   end
 end