updates based on PR feedback

docs/testing-guidelines/PesterDoAndDont.md

@@ -4,7 +4,7 @@
 	1. Test only what you need
 	2. Reduce dependencies
 3. Be sure to tag your `Describe` blocks based on their purpose
-	1. Tag `CI` indicates that it will be run as part of the continuous integration process. These should be unit test like, and fast.
+	1. Tag `CI` indicates that it will be run as part of the continuous integration process. These should be unit test like, and generally take less than a second.
 	2. Tag `Feature` indicates a higher level feature test (we will run these on a regular basis), for example, tests which go to remote resources, or test broader functionality
 	3. Tag `Scenario` indicates tests of integration with other features (these will be run on a less regular basis and test even broader functionality than feature tests.
 4. Make sure that `Describe`/`Context`/`It` descriptions are useful
@@ -12,14 +12,22 @@
 5. Use `Context` to group tests
 	1. Multiple `Context` blocks can help you group your test suite into logical sections
 6. Use `BeforeAll`/`AfterAll`/`BeforeEach`/`AfterEach` instead of custom initiators
-7. Use Try-Catch for expected errors and check $_.fullyQualifiedErrorId (don't use `should throw`)
+7. Prefer Try-Catch for expected errors and check $_.fullyQualifiedErrorId (don't use `should throw`)
 8. Use `-testcases` when iterating over multiple `It` blocks
 9. Use code coverage functionality where appropriate
 10. Use `Mock` functionality when you don't have your entire environment
 11. Avoid free code in a `Describe` block
-	1. Use `[Before|After][Each|All]` _see Free Code in a Describe block_
-
+	1. Use `[Before|After][Each|All]` see [Free Code in a Describe block](WritingPesterTests.md#free-code-in-a-describe-block)
+12. Avoid creating or using test files outside of TESTDRIVE:
+    1. TESTDRIVE: has automatic clean-up
+13. Keep in mind that we are creating cross platform tests
+    1. Avoid using the registry
+    2. Avoid using COM
+14. Avoid being too specific about the _count_ of a resource as these can change platform to platform
+    1. ex: checking for the count of loaded format files, check rather for format data for a specific type
 ## Don't
-1. Have too many evaluations in a single It block
+1. Don't have too many evaluations in a single It block
 	1. The first `Should` failure will stop that block
-2.  `Should` be used in an `It` Block
+2. Don't use `Should` outside of an `It` Block
+3. Don't use the word "Error" or "Fail" to test a positive case
+    1. ex: "Get-Childitem TESTDRIVE: shouldn't fail", rather "Get-ChildItem should be able to retrieve file listing from TESTDRIVE"