Translate from @types package to library name

npm_and_yarn/lib/dependabot/npm_and_yarn/package_name.rb

@@ -11,6 +11,13 @@ class PackageName
           (?<name>[a-z0-9\-~][a-z0-9\-._~]*)         # capture package name
           \z                                         # end of string
       }xi.freeze                                     # multi-line/case-insensitive
+      TYPES_PACKAGE_NAME_REGEX = %r{
+          \A                                         # beginning of string
+          @#{DEFINITELY_TYPED_SCOPE}\/               # starts with @types/
+          ((?<scope>.+)__)?                          # capture scope
+          (?<name>.+)                                # capture name
+          \z                                         # end of string
+      }xi.freeze                                     # multi-line/case-insensitive
 
       class InvalidPackageName < StandardError; end
 
@@ -38,6 +45,20 @@ def eql?(other)
         to_s.eql?(other.to_s)
       end
 
+      def library_name
+        return self unless types_package?
+
+        @library_name ||=
+          begin
+            match = TYPES_PACKAGE_NAME_REGEX.match(to_s)
+            if match[:scope]
+              self.class.new("@#{match[:scope]}/#{match[:name]}")
+            else
+              self.class.new(match[:name].to_s)
+            end
+          end
+      end
+
       def types_package_name
         return self if types_package?
 

npm_and_yarn/spec/dependabot/npm_and_yarn/package_name_spec.rb

@@ -65,6 +65,36 @@
     end
   end
 
+  describe "#library_name" do
+    it "returns self if it is not a types package" do
+      jquery = "jquery"
+
+      library_name = described_class.new(jquery).library_name.to_s
+
+      expect(library_name).to eq(jquery)
+    end
+
+    it "returns the corresponding library for a types package" do
+      lodash_types = "@types/lodash"
+      lodash       = "lodash"
+
+      library_name = described_class.new(lodash_types).library_name
+
+      expect(library_name.to_s).to eq(lodash)
+    end
+
+    context "when it is a scoped types package" do
+      it "returns the type packages scoped name" do
+        babel_core_types = "@types/babel__core"
+        babel_core       = "@babel/core"
+
+        library_name = described_class.new(babel_core_types).library_name
+
+        expect(library_name.to_s).to eq(babel_core)
+      end
+    end
+  end
+
   describe "#eql?" do
     it "compares the string representation of the package name" do
       package       = described_class.new("package")