test: actually test output from running demo server code

I was invoking demo mode, but not testing the output to verify it was
making it to the point where it would start the server.

Check that an expected database file was created to verify that the db
setting was honored.

Also test TEMPLATE-INFO.txt to verify that the correct template was
being instantiated.

Tested under 3.13 as wel using docker command line (wrapped):

   docker run -it -u 1000 --rm -v $PWD:/usr/src/myapp -w
   /usr/src/myapp  python:3.13.0a1-alpine3.18 sh -c 'export
   HOME=/tmp/home; mkdir $HOME; python -m pip install pytest
   pytest-env requests jinja2; python -m pytest -v test/test_demo.py'

If demo mode tries to start as root, it exits with an error, so it
must be run with -u uid.

test/test_demo.py

@@ -84,14 +84,63 @@ def test_get_server(self):
         self.assertIn("Keyboard Interrupt: exiting", output.split('\n'))
 
     def testDemoClassic(self):
-        self.run_install_demo("classic")
+        with captured_output() as (out, err):
+            self.run_install_demo("classic")
+        self.assertIn("http://localhost:8917/demo/", out.getvalue())
+
+        # verify the default anydbm db is created
+        db_file = self.home + "/db/nodes.user"
+        self.assertTrue(os.path.isfile(db_file),
+                        "expected db file %s does not exist" % db_file)
+
+         # verify requested template was used
+        with open(self.home + "/TEMPLATE-INFO.txt", "r") as f:
+            info_lines = f.read()
+
+        try:
+            # handle text files with \r\n line endings
+            info_lines.index("\r", 0, 100)
+            info_lines = info_lines.replace("\r\n", "\n")
+        except ValueError:
+            pass
+
+        self.assertIn("Name: classic-_test_demo\n", info_lines)
 
     def testDemoMinimal(self):
-        self.run_install_demo('../templates/minimal', db="sqlite")
+        # test explicit path to template as others test template
+        # search path.
+        with captured_output() as (out, err):
+            self.run_install_demo('../templates/minimal', db="sqlite")
+        self.assertIn("http://localhost:8917/demo/", out.getvalue())
+
+        # verify the requested sqlite db file is created
+        db_file = self.home + "/db/db"
+        self.assertTrue(os.path.isfile(db_file),
+                        "expected db file %s does not exist" % db_file)
+
+        # verify requested template was used
+        with open(self.home + "/TEMPLATE-INFO.txt", "r") as f:
+            info_lines = f.read()
+
+        try:
+            # handle text files with \r\n line endings
+            info_lines.index("\r", 0, 100)
+            info_lines = info_lines.replace("\r\n", "\n")
+        except ValueError:
+            pass
+
+        self.assertIn("Name: minimal-_test_demo\n", info_lines)
 
     @skip_jinja2
     def testDemoJinja(self):
-        self.run_install_demo('jinja2', db="anydbm")
+        with captured_output() as (out, err):
+            self.run_install_demo('jinja2', db="anydbm")
+        self.assertIn("http://localhost:8917/demo/", out.getvalue())
+
+        # verify the requested anydbm db file is created
+        db_file = self.home + "/db/nodes.user"
+        self.assertTrue(os.path.isfile(db_file),
+                        "expected db file %s does not exist" % db_file)
 
         # verify that template was set to jinja2 by reading config
         with open(self.home + "/config.ini", "r") as f: