Add tests to validate spark environment prereqs

README.md

@@ -8,6 +8,7 @@ Please make sure you have the following installed and can run them
 * [Poetry](https://python-poetry.org/docs/#installation)
 * Java (11)
   * To run pySpark, it's important that the environment variable `JAVA_HOME` is set correctly, check via `echo $JAVA_HOME`
+  * [test_validate_spark_environment.py](/tests/integration/test_validate_spark_environment.py) will help you figure out if your environment will work
 
 ## Install all dependencies
 ```bash

tests/integration/test_validate_spark_environment.py

@@ -0,0 +1,23 @@
+import os
+import subprocess
+
+
+def test_java_home_is_set():
+    java_home = os.environ.get("JAVA_HOME")
+    assert java_home is not None, "Environment variable 'JAVA_HOME' is not set but is required by pySpark to work."
+
+
+def test_java_version_is_greater_or_equal_11():
+    java_version = subprocess.check_output(['java', '-version'], stderr=subprocess.STDOUT).decode("utf-8")
+    print(f"\n`java -version` returned\n{java_version}")
+    version_number = java_version.splitlines()[0].split('"')[1].strip('"')
+    print(f"Assuming {version_number=} is the version to check.")
+    version_identifier_at_idx_0, version_identifier_at_idx_1, _ = version_number.split('.')
+    if eval(version_identifier_at_idx_0) == 1:
+        print(
+            f"Found {version_identifier_at_idx_0=}, this is not the major version. Using {version_identifier_at_idx_1=} to check version requirements.")
+        actual_major_version = eval(version_identifier_at_idx_1)
+    else:
+        actual_major_version = eval(version_identifier_at_idx_0)
+    expected_major_version = 11
+    assert actual_major_version >= expected_major_version, f"Major version {actual_major_version} is not recent enough, we need at least version {expected_major_version}."