Latex tests

tests/python/test_latex.py

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+import pytest
+from tempfile import TemporaryDirectory
+from shutil import which
+from os.path import exists
+from re import match
+from PySide6.QtGui import QColor
+
+from LogarithmPlotter.util import latex
+
+latex.SHOW_GUI_MESSAGES = False
+
+
+@pytest.fixture()
+def latex_obj():
+    directory = TemporaryDirectory()
+    obj = latex.Latex(directory)
+    if not obj.checkLatexInstallation():
+        raise Exception("Cannot run LaTeX tests without a proper LaTeX installation. Make sure to install a LaTeX distribution, DVIPNG, and the calligra package, and run the tests again.")
+    yield obj
+    directory.cleanup()
+
+
+class TestLatex:
+    def test_check_install(self, latex_obj: latex.Latex) -> None:
+        assert latex_obj.latexSupported == True
+        assert latex_obj.checkLatexInstallation() == True
+        bkp = [latex.DVIPNG_PATH, latex.LATEX_PATH]
+        # Check what happens when one is missing.
+        latex.DVIPNG_PATH = None
+        assert latex_obj.latexSupported == False
+        assert latex_obj.checkLatexInstallation() == False
+        latex.DVIPNG_PATH = bkp[0]
+        latex.LATEX_PATH = None
+        assert latex_obj.latexSupported == False
+        assert latex_obj.checkLatexInstallation() == False
+        # Reset
+        [latex.DVIPNG_PATH, latex.LATEX_PATH] = bkp
+
+    def test_render(self, latex_obj: latex.Latex) -> None:
+        result = latex_obj.render(r"\frac{d\sqrt{\mathrm{f}(x \times 2.3)}}{dx}", 14, QColor(0, 0, 0, 255))
+        # Ensure result format
+        assert type(result) == str
+        [path, width, height] = result.split(",")
+        assert exists(path)
+        assert match(r"\d+", width)
+        assert match(r"\d+", height)
+        # Ensure it returns errors on invalid latex.
+        with pytest.raises(latex.RenderError):
+            latex_obj.render(r"\nonexistant", 14, QColor(0, 0, 0, 255))
+        # Replace latex bin with one that returns errors
+        bkp = latex.LATEX_PATH
+        latex.LATEX_PATH = which("false")
+        with pytest.raises(latex.RenderError):
+            latex_obj.render(r"\mathrm{f}(x)", 14, QColor(0, 0, 0, 255))
+        latex.LATEX_PATH = bkp
+
+    def test_prerendered(self, latex_obj: latex.Latex) -> None:
+        args = [r"\frac{d\sqrt{\mathrm{f}(x \times 2.3)}}{dx}", 14, QColor(0, 0, 0, 255)]
+        latex_obj.render(*args)
+        prerendered = latex_obj.findPrerendered(*args)
+        assert type(prerendered) == str
+        [path, width, height] = prerendered.split(",")
+        assert exists(path)
+        assert match(r"\d+", width)
+        assert match(r"\d+", height)
+        prerendered2 = latex_obj.findPrerendered(args[0], args[1]+2, args[2])
+        assert prerendered2 == ""
+