Move testing knowledge from community to microsoft layer

Relocates the six P1+P2 testing-domain articles (18 files: .md + .good.al + .bad.al each) from community/knowledge/testing/ to microsoft/knowledge/testing/ per maintainer request. Pure git-mv rename; no content or frontmatter changes.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

microsoft/knowledge/testing/asserterror-needs-expectederror-and-code.good.al

@@ -0,0 +1,23 @@
+codeunit 50408 "Test AssertError Good"
+{
+    Subtype = Test;
+
+    [Test]
+    procedure BlankNameIsRejectedWithSpecificError()
+    var
+        Customer: Record Customer;
+    begin
+        Customer.Init();
+        Customer.Name := '';
+
+        // [WHEN] a mandatory field is blank
+        asserterror Customer.TestField(Name);
+
+        // [THEN] verify the SPECIFIC failure — message and code — not just "any error"
+        Assert.ExpectedError('Name must have a value');
+        Assert.ExpectedErrorCode('TestField');
+    end;
+
+    var
+        Assert: Codeunit "Library Assert";
+}