How to use the fontmake.instantiator.Instantiator.from_designspace function in fontmake

def test_axis_mapping_manual_os2_classes(data_dir):
    designspace = designspaceLib.DesignSpaceDocument.fromfile(
        data_dir / "DesignspaceTest" / "DesignspaceTest-wght-wdth.designspace"
    )
    designspace.loadSourceFonts(ufoLib2.Font.open)
    designspace.sources[0].font.info.openTypeOS2WeightClass = 800
    designspace.sources[0].font.info.openTypeOS2WidthClass = 7
    designspace.sources[1].font.info.openTypeOS2WeightClass = 900
    designspace.sources[1].font.info.openTypeOS2WidthClass = 9
    generator = fontmake.instantiator.Instantiator.from_designspace(
        designspace, round_geometry=True
    )

    instance_font = generator.generate_instance(designspace.instances[0])
    assert instance_font.info.openTypeOS2WeightClass == 850
    assert instance_font.info.openTypeOS2WidthClass == 8
    assert instance_font.info.italicAngle is None
    assert instance_font.lib["designspace.location"] == [
        ("weight", 100.0),
        ("width", 100.0),
    ]

def test_axis_mapping_no_os2_class_inference(data_dir):
    designspace = designspaceLib.DesignSpaceDocument.fromfile(
        data_dir / "DesignspaceTest" / "DesignspaceTest-opsz.designspace"
    )
    generator = fontmake.instantiator.Instantiator.from_designspace(
        designspace, round_geometry=True
    )

    instance_font = generator.generate_instance(designspace.instances[0])
    assert instance_font.info.openTypeOS2WeightClass is None
    assert instance_font.info.openTypeOS2WidthClass is None
    assert instance_font.info.italicAngle is None
    assert instance_font.lib["designspace.location"] == [("optical", 15.0)]

def test_interpolation_no_rounding(data_dir):
    designspace = designspaceLib.DesignSpaceDocument.fromfile(
        data_dir / "MutatorSans" / "MutatorSans.designspace"
    )
    designspace.instances[4].location = {"weight": 123.456, "width": 789.123}
    generator = fontmake.instantiator.Instantiator.from_designspace(
        designspace, round_geometry=False
    )

    instance_font = generator.generate_instance(designspace.instances[4])
    assert isinstance(instance_font.info.ascender, float)
    assert isinstance(instance_font.kerning[("A", "J")], float)
    assert isinstance(instance_font["A"].contours[0][0].x, float)

def test_raise_failed_glyph_interpolation(data_dir):
    designspace = designspaceLib.DesignSpaceDocument.fromfile(
        data_dir / "DesignspaceBrokenTest" / "DesignspaceTest.designspace"
    )
    generator = fontmake.instantiator.Instantiator.from_designspace(designspace)

    with pytest.raises(
        fontmake.instantiator.InstantiatorError, match="Failed to generate instance"
    ):
        for instance in designspace.instances:
            instance.font = generator.generate_instance(instance)

def test_instance_attributes(data_dir):
    designspace = designspaceLib.DesignSpaceDocument.fromfile(
        data_dir / "DesignspaceTest" / "DesignspaceTest-instance-attrs.designspace"
    )
    generator = fontmake.instantiator.Instantiator.from_designspace(
        designspace, round_geometry=True
    )

    instance_font = generator.generate_instance(designspace.instances[0])
    assert instance_font.info.familyName == "aaa"
    assert instance_font.info.styleName == "sss"
    assert instance_font.info.postscriptFontName == "ppp"
    assert instance_font.info.styleMapFamilyName == "yyy"
    assert instance_font.info.styleMapStyleName == "xxx"

def test_interpolation_rounding(data_dir):
    designspace = designspaceLib.DesignSpaceDocument.fromfile(
        data_dir / "MutatorSans" / "MutatorSans.designspace"
    )
    designspace.instances[4].location = {"weight": 123.456, "width": 789.123}
    generator = fontmake.instantiator.Instantiator.from_designspace(
        designspace, round_geometry=True
    )

    instance_font = generator.generate_instance(designspace.instances[4])
    assert isinstance(instance_font.info.ascender, int)
    assert isinstance(instance_font.kerning[("A", "J")], int)
    assert isinstance(instance_font["A"].contours[0][0].x, int)

def test_axis_mapping_no_os2_width_class_inference(data_dir):
    designspace = designspaceLib.DesignSpaceDocument.fromfile(
        data_dir / "DesignspaceTest" / "DesignspaceTest-bare.designspace"
    )
    designspace.loadSourceFonts(ufoLib2.Font.open)
    designspace.sources[0].font.info.openTypeOS2WeightClass = 800
    designspace.sources[1].font.info.openTypeOS2WeightClass = 900
    generator = fontmake.instantiator.Instantiator.from_designspace(
        designspace, round_geometry=True
    )

    instance_font = generator.generate_instance(designspace.instances[0])
    assert instance_font.info.openTypeOS2WeightClass == 850
    assert instance_font.info.openTypeOS2WidthClass is None
    assert instance_font.info.italicAngle is None
    assert instance_font.lib["designspace.location"] == [("weight", 100.0)]