Add specs for `CaskLoader`.

Library/Homebrew/test/cask/cask_loader/from_content_loader_spec.rb

+describe Hbc::CaskLoader::FromContentLoader do
+  alias_matcher :be_able_to_load, :be_can_load
+
+  describe "::can_load?" do
+    it "returns true for Casks specified with `cask \"token\" do … end`" do
+      expect(described_class).to be_able_to_load <<~EOS
+        cask "token" do
+        end
+      EOS
+    end
+
+    it "returns true for Casks specified with `cask \"token\" do; end`" do
+      expect(described_class).to be_able_to_load <<~EOS
+        cask "token" do; end
+      EOS
+    end
+
+    it "returns true for Casks specified with `cask 'token' do … end`" do
+      expect(described_class).to be_able_to_load <<~EOS
+        cask 'token' do
+        end
+      EOS
+    end
+
+    it "returns true for Casks specified with `cask 'token' do; end`" do
+      expect(described_class).to be_able_to_load <<~EOS
+        cask 'token' do; end
+      EOS
+    end
+
+    it "returns true for Casks specified with `cask(\"token\") { … }`" do
+      expect(described_class).to be_able_to_load <<~EOS
+        cask("token") {
+        }
+      EOS
+    end
+
+    it "returns true for Casks specified with `cask(\"token\") {}`" do
+      expect(described_class).to be_able_to_load <<~EOS
+        cask("token") {}
+      EOS
+    end
+
+    it "returns true for Casks specified with `cask('token') { … }`" do
+      expect(described_class).to be_able_to_load <<~EOS
+        cask('token') {
+        }
+      EOS
+    end
+
+    it "returns true for Casks specified with `cask('token') {}`" do
+      expect(described_class).to be_able_to_load <<~EOS
+        cask('token') {}
+      EOS
+    end
+  end
+end

Library/Homebrew/test/cask/cask_loader/from_uri_loader_spec.rb

+describe Hbc::CaskLoader::FromURILoader do
+  alias_matcher :be_able_to_load, :be_can_load
+
+  describe "::can_load?" do
+    it "returns true when given an URI" do
+      expect(described_class).to be_able_to_load(URI("http://example.com/"))
+    end
+
+    it "returns true when given a String which can be parsed to a URI" do
+      expect(described_class).to be_able_to_load("http://example.com/")
+    end
+
+    it "returns false when given a String with Cask contents containing a URL" do
+      expect(described_class).not_to be_able_to_load <<~EOS
+        cask 'token' do
+          url 'http://example.com/'
+        end
+      EOS
+    end
+  end
+end