old_contents: from tests.lib import create_basic_wheel_for_package
  
  
  def test_new_resolver_conflict_requirements_file(tmpdir, script):
      create_basic_wheel_for_package(script, "base", "1.0")
      create_basic_wheel_for_package(script, "base", "2.0")
      create_basic_wheel_for_package(
          script, "pkga", "1.0", depends=["base==1.0"],
      )
      create_basic_wheel_for_package(
          script, "pkgb", "1.0", depends=["base==2.0"],
      )
  
      req_file = tmpdir.joinpath("requirements.txt")
      req_file.write_text("pkga\npkgb")
  
      result = script.pip(
          "install",
          "--no-cache-dir", "--no-index",
          "--find-links", script.scratch_path,
          "-r", req_file,
          expect_error=True,
      )
  
      message = "package versions have conflicting dependencies"
      assert message in result.stderr, str(result)
  
new_contents: from tests.lib import create_basic_wheel_for_package
  
  
  def test_new_resolver_conflict_requirements_file(tmpdir, script):
      create_basic_wheel_for_package(script, "base", "1.0")
      create_basic_wheel_for_package(script, "base", "2.0")
      create_basic_wheel_for_package(
          script, "pkga", "1.0", depends=["base==1.0"],
      )
      create_basic_wheel_for_package(
          script, "pkgb", "1.0", depends=["base==2.0"],
      )
  
      req_file = tmpdir.joinpath("requirements.txt")
      req_file.write_text("pkga\npkgb")
  
      result = script.pip(
          "install",
          "--no-cache-dir", "--no-index",
          "--find-links", script.scratch_path,
          "-r", req_file,
          expect_error=True,
      )
  
      message = "package versions have conflicting dependencies"
      assert message in result.stderr, str(result)
  
  
  def test_new_resolver_conflict_constraints_file(tmpdir, script):
      create_basic_wheel_for_package(script, "pkg", "1.0")
  
      constrats_file = tmpdir.joinpath("constraints.txt")
      constrats_file.write_text("pkg!=1.0")
  
      result = script.pip(
          "install",
          "--no-cache-dir", "--no-index",
          "--find-links", script.scratch_path,
          "-c", constrats_file,
          "pkg==1.0",
          expect_error=True,
      )
  
      assert "ResolutionImpossible" in result.stderr, str(result)
  
      message = "The user requested (constraint) pkg!=1.0"
      assert message in result.stdout, str(result)
  
subject: Test for constraint in message