[roottest] Use nbconvert as a library in nbdiff.py

Author: guitargeek

roottest/python/JupyROOT/nbdiff.py

@@ -6,7 +6,6 @@
 import tempfile
 
 nbExtension = ".ipynb"
-pythonInterpName = sys.executable
 
 rootKernelFileContent = (
     """{
@@ -21,7 +20,7 @@
  ]
 }
 """
-    % pythonInterpName
+    % sys.executable
 )
 
 
@@ -148,24 +147,39 @@ def getKernelName(inNBName):
 
 
 def canReproduceNotebook(inNBName, needsCompare):
+    from nbconvert import NotebookExporter
+    from nbconvert.preprocessors import ExecutePreprocessor
+    import nbformat
+
     tmpDir = addEtcToEnvironment(os.path.dirname(inNBName))
     outNBName = inNBName.replace(nbExtension, "_out" + nbExtension)
-    convCmd = (
-        "%s -m jupyter nbconvert "
-        "--to notebook "
-        "--ExecutePreprocessor.kernel_name=%s "
-        "--ExecutePreprocessor.enabled=True "
-        "--ExecutePreprocessor.timeout=3600 "
-        "--ExecutePreprocessor.startup_timeout=180 "
-        "%s "
-        "--output %s" % (pythonInterpName, getKernelName(inNBName), inNBName, outNBName)
+
+    # Load input notebook
+    with open(inNBName, "r", encoding="utf-8") as f:
+        nb = nbformat.read(f, as_version=4)
+
+    # Configure execution
+    ep = ExecutePreprocessor(
+        kernel_name=getKernelName(inNBName),
+        timeout=3600,
+        startup_timeout=180,
+        allow_errors=False,
     )
-    exitStatus = os.system(convCmd)  # we use system to inherit the environment in os.environ
-    shutil.rmtree(tmpDir)
+
+    # Run the notebook
+    ep.preprocess(nb, {"metadata": {"path": os.path.dirname(inNBName)}})
+
+    # Export executed notebook
+    with open(outNBName, "w", encoding="utf-8") as f:
+        nbformat.write(nb, f)
+
+    # Compare or return success
     if needsCompare:
         return compareNotebooks(inNBName, outNBName)
     else:
-        return exitStatus
+        return 0  # success
+
+    shutil.rmtree(tmpDir)
 
 
 def isInputNotebookFileName(filename):