pygmt.show_versions: Add a test to check GMT-Ghostscript warnings (#3433)

Author: seisman

pygmt/tests/test_show_versions.py

@@ -5,16 +5,43 @@
 import io
 
 import pygmt
+import pytest
 
 
 def test_show_versions():
     """
-    Check that pygmt.show_versions() reports version information from PyGMT, the
-    operating system, dependencies and the GMT library.
+    Check that pygmt.show_versions reports version information of PyGMT, the operating
+    system, dependencies and the GMT library.
     """
     buf = io.StringIO()
     pygmt.show_versions(file=buf)
-    assert "PyGMT information:" in buf.getvalue()
-    assert "System information:" in buf.getvalue()
-    assert "Dependency information:" in buf.getvalue()
-    assert "GMT library information:" in buf.getvalue()
+    output = buf.getvalue()
+
+    assert "PyGMT information:" in output
+    assert "System information:" in output
+    assert "Dependency information:" in output
+    assert "GMT library information:" in output
+    assert "WARNING:" not in output  # No GMT-Ghostscript incompatibility warnings.
+
+
+@pytest.mark.parametrize(
+    ("gs_version", "gmt_version"),
+    [
+        ("9.52", "6.4.0"),
+        ("10.01", "6.4.0"),
+        ("10.02", "6.4.0"),
+        (None, "6.5.0"),
+    ],
+)
+def test_show_versions_ghostscript_warnings(gs_version, gmt_version, monkeypatch):
+    """
+    Check that pygmt.show_versions reports warnings for GMT-Ghostscript incompatibility.
+    """
+    monkeypatch.setattr("pygmt._show_versions.__gmt_version__", gmt_version)
+    monkeypatch.setattr(
+        "pygmt._show_versions._get_ghostscript_version", lambda: gs_version
+    )
+
+    buf = io.StringIO()
+    pygmt.show_versions(file=buf)
+    assert "WARNING:" in buf.getvalue()