code: def test_linear_region_color():
      """Test the color argument of LinearRegionVisual.set_data() method
      using a single color
      """
      # Definition of the region
      pos1 = [5, 42]
      # Definition of the color of the region
      color1 = np.array([0.0, 1.0, 0.0, 0.5], dtype=np.float32)
      # Expected internal color buffer
      color1_expected = np.array(
          [color1, color1, color1, color1], dtype=np.float32
      )
  
      with TestingCanvas() as c:
          # Check set_data is working correctly within visual constructor
          region = visuals.LinearRegion(
              pos=pos1, color=color1, parent=c.scene
          )
          assert np.all(region._color == color1_expected)
          assert np.all(region.color == color1)
  
          # Check set_data is working as expected when passing a list as
          # color argument
          region.set_data(color=list(color1))
          assert np.all(region._color == color1_expected)
          assert np.all(region.color == color1)
  
          # Check set_data is working as expected when passing a tuple as
          # color argument
          region.set_data(color=tuple(color1))
          assert np.all(region._color == color1_expected)
          assert np.all(region.color == color1)
  
          # Test with different dtypes that must be converted to float32
          region.set_data(color=color1.astype(np.float64))
          assert np.all(region._color == color1_expected)
          assert np.all(region.color == color1)
  
          assert_image_approved(
              c.render(), "visuals/linear_region1.png"
          )
  
          # Check a ValueError is raised when the length of color argument
          # is not 4.
          assert_raises(
              ValueError, region.set_data, color=[1.0, 0.5, 0.5]
          )
  
          # Check a ValueError is raised when too many colors are provided
          assert_raises(
              ValueError,
              region.set_data,
              color=[color1, color1, color1],
          )
  
file_path: vispy/vispy/visuals/tests/test_linear_region.py
imports: import numpy
  from vispy.scene import visuals
  from vispy.testing import requires_application, TestingCanvas, run_tests_if_main
  from vispy.testing.image_tester import assert_image_approved
  from vispy.testing import assert_raises
label_desc: Use image node_id 2 for calling a global function with example usage: test_linear_region_color() without return types