Selecting the correct requirement based on the given marker condition. (

#11204)

* Selecting the correct requirement based on the given marker condition.

* Lint error fixes

* Updated as per the review comment and added a test.

* Removing the null check as per the comment.

---------

Co-authored-by: “Thavachelvam <“thavaahariharangit@git.com”>

python/lib/dependabot/python/file_parser.rb

@@ -294,10 +294,37 @@ def group_from_filename(filename)
 
       def blocking_marker?(dep)
         return false if dep["markers"] == "None"
-        return true if dep["markers"].include?("<")
-        return false if dep["markers"].include?(">")
 
-        dep["requirement"]&.include?("<")
+        marker = dep["markers"]
+        version = python_raw_version
+
+        if marker.include?("python_version")
+          !marker_satisfied?(marker, version)
+        else
+          return true if dep["markers"].include?("<")
+          return false if dep["markers"].include?(">")
+
+          dep["requirement"]&.include?("<")
+        end
+      end
+
+      def marker_satisfied?(marker, python_version)
+        operator, version = marker.match(/([<>=!]=?)\s*"?([\d.]+)"?/).captures
+
+        case operator
+        when "<"
+          Dependabot::Python::Version.new(python_version) < Dependabot::Python::Version.new(version)
+        when "<="
+          Dependabot::Python::Version.new(python_version) <= Dependabot::Python::Version.new(version)
+        when ">"
+          Dependabot::Python::Version.new(python_version) > Dependabot::Python::Version.new(version)
+        when ">="
+          Dependabot::Python::Version.new(python_version) >= Dependabot::Python::Version.new(version)
+        when "=="
+          Dependabot::Python::Version.new(python_version) == Dependabot::Python::Version.new(version)
+        else
+          false
+        end
       end
 
       def setup_file_dependencies

python/spec/dependabot/python/file_parser_spec.rb

@@ -106,10 +106,40 @@
     end
 
     context "with markers" do
-      context "when including a < in the marker" do
+      context "when the marker <= 2.6" do
+        before do
+          allow(parser).to receive(:python_raw_version).and_return("2.6")
+        end
+
         let(:requirements_fixture_name) { "markers.txt" }
 
-        it "parses only the >= marker" do
+        it "then the dependency version should be 1.0.4" do
+          expect(dependencies.length).to eq(1)
+
+          dependency = dependencies.first
+
+          expect(dependency).to be_a(Dependabot::Dependency)
+          expect(dependency.name).to eq("distro")
+          expect(dependency.version).to eq("1.0.4")
+          expect(dependency.requirements).to eq(
+            [{
+              requirement: "==1.0.4",
+              file: "requirements.txt",
+              groups: ["dependencies"],
+              source: nil
+            }]
+          )
+        end
+      end
+
+      context "when the marker => 2.7" do
+        before do
+          allow(parser).to receive(:python_raw_version).and_return("2.7")
+        end
+
+        let(:requirements_fixture_name) { "markers.txt" }
+
+        it "then the dependency version should be 1.3.0" do
           expect(dependencies.length).to eq(1)
 
           dependency = dependencies.first