Add FileDescriptor#imports and #public_imports

lib/proto_plugin/file_descriptor.rb

@@ -108,6 +108,34 @@ def services
       end
     end
 
+    # The files imported by this file, resolved to their descriptors.
+    #
+    # Imports that were not included in the request are omitted.
+    #
+    # @return [Array<FileDescriptor>]
+    #
+    # @see https://github.com/protocolbuffers/protobuf/blob/v28.2/src/google/protobuf/descriptor.proto#L100
+    #   Google::Protobuf::FileDescriptorProto#dependency
+    def imports
+      @imports ||= @descriptor.dependency.filter_map do |name|
+        @context.file_by_filename(name)
+      end
+    end
+
+    # The subset of {#imports} that were declared with `import public`, resolved
+    # to their descriptors.
+    #
+    # @return [Array<FileDescriptor>]
+    #
+    # @see https://github.com/protocolbuffers/protobuf/blob/v28.2/src/google/protobuf/descriptor.proto#L103
+    #   Google::Protobuf::FileDescriptorProto#public_dependency
+    def public_imports
+      @public_imports ||= @descriptor.public_dependency.filter_map do |i|
+        name = @descriptor.dependency[i]
+        @context.file_by_filename(name) if name
+      end
+    end
+
     private
 
     # Field numbers of the relevant repeated fields within their parent

test/fixtures/blog/article.proto

@@ -4,7 +4,7 @@ package proto_plugin.fixtures;
 
 import "google/protobuf/timestamp.proto";
 
-import "comment.proto";
+import public "comment.proto";
 
 // An article published on the blog.
 message Article {

test/proto_plugin/file_descriptor_test.rb

@@ -47,6 +47,33 @@ def test_services
       assert_instance_of(ServiceDescriptor, service_one)
     end
 
+    def test_imports
+      file = @context.file_by_filename("article.proto")
+
+      assert_equal(
+        ["google/protobuf/timestamp.proto", "comment.proto"],
+        file.imports.map(&:name),
+      )
+
+      file.imports.each do |i|
+        assert_instance_of(FileDescriptor, i)
+      end
+    end
+
+    def test_public_imports
+      file = @context.file_by_filename("article.proto")
+
+      assert_equal(["comment.proto"], file.public_imports.map(&:name))
+      assert_instance_of(FileDescriptor, file.public_imports.first)
+    end
+
+    def test_imports_empty_without_dependencies
+      file = @context.file_by_filename("category.proto")
+
+      assert_empty(file.imports)
+      assert_empty(file.public_imports)
+    end
+
     def test_namespace_without_package
       file = FileDescriptor.new(@context, Google::Protobuf::FileDescriptorProto.new(
         name: "sample.proto",