diff --git a/HowToWriteTests.md b/HowToWriteTests.md
index 78a2437..f334d95 100644
--- a/HowToWriteTests.md
+++ b/HowToWriteTests.md
@@ -7,17 +7,22 @@ touch src/allmydata/test/test_fname.py
 ```
 
 ```
-python setup.py trial -s allmydata.test.test_fname
+python -m twisted.trial trial allmydata.test.test_fname
 ```
 
-Okay, so it didn't work, because there is no file by that name. Create such a file, with these contents:
+Okay, so that was boring because there are no tests in the file.  Add these contents:
 
 ```
-from twisted.trial import unittest
+from testtools.matchers import (
+    Never,
+)
+from .common import (
+    TestCase,
+)
 
-class T(unittest.TestCase):
+class T(TestCase):
     def test_a(self):
-        pass
+        self.assertThat("a", Never())
 ```
 
 Now run it!
@@ -27,18 +32,14 @@ Now run it!
 Now install Ned Batchelder's "[coverage"](http://nedbatchelder.com/code/coverage/) tool and run your test with code coverage, like this:
 
 ```
-python setup.py trial --coverage -s allmydata.test.test_fname
+python -m coverage run -m twisted.trial allmydata.test.test_fname
 ```
 
-This does the same as running the tests without coverage -- print a list of what happened when each test was run. It also writes out a file named `.coverage` into the current directory. Run the following command to read that file and produce nice HTML pages:
+This does the same as running the tests without coverage -- print a list of what happened when each test was run. It also writes out a file named `.coverage.<something>` into the current directory. Run the following command to read that file and produce nice HTML pages:
 
 ```
-coverage html
-```
-
-If you installed coverage from Debian or Ubuntu then you have to name it `python-coverage`, like this:
-```
-python-coverage html
+python -m coverage combine
+python -m coverage html
 ```
 
 That will product a directory named `htmlcov`. View its contents with a web browser.