SERVER-43367 unittest framework refactor/fixes

  - Segregate old-style dbtests into their own Suite initialization
    system: OldStyleSuiteSpecification. This is where the funky
    deprecated features can live on without interfering with the
    Suite API.  It also gives us a searchable base class to identify
    them in the future.

    OldStyleSuite has `setupTests()` and an `add<T>()` that
    Suite does not have.  Suite API can shrink when it doesn't
    have to support these dbtest adaptor features.
    Suite only needs non-template `add(name, callback)`.

  - Add OldStyleSuiteInitializer to some dbtests that were missing it!
    These didn't use SuiteInstance to register themselves and were
    incorrect.  They would self register, resulting in _allSuites()
    holding a std::shared_ptr to a static-duration Suite object!

  - Change `getSuite()` to return `Suite&` instead of `Suite*`.

  - No more "self-registering" in Suite constructor. Registration
    must be done as a separate post-construction step. This removes
    some unusual lifetime management code and is easier to document.
    Suite::getSuite(name) is the only way to make a Suite, and it
    does the make_shared and registration calls with a pseudo-private
    ConstructorEnable idiom.

  - Suite->run() returns std::unique_ptr<Result> instead of
    raw `Result*`. It's virtual to support OldStyleSuite behavior.

  - Suite._ran does nothing. Removed.

  - Result.cur does nothing. Removed.

  - Switch to pass-by-value and std::move for most ctor args.

  - Add explicit on 1-arg ctors.

  - Get rid of TestHolder. It's just a 2-field struct.

  - use fmt instead of snprintf

  - TEST and TEST_F macros: generate TEST_TYPE once.
  - TEST and TEST_F macros: inline the _agent variable.
  - Mark _doRun as `override`.
  - Terminology: replace CASE_NAME with SUITE_NAME.

  - rename DeathTestImpl -> DeathTestBase
  - move getDeathTestPattern into the test as a static member function

  - refactor out some repetition from the comparator decl macros

  - use if-constexpr and diamond relops to clean up the
    ComparisonAssertion class.

    - dbtests: conditionally skip some add<T> calls

    - further dedup (DEATH_)TEST(_F) macros

1 files changed, 5 insertions, 3 deletions

diff --git a/src/mongo/dbtests/dbhelper_tests.cpp b/src/mongo/dbtests/dbhelper_tests.cpp
index 427faa513de..f2b567c4a7b 100644
--- a/src/mongo/dbtests/dbhelper_tests.cpp
+++ b/src/mongo/dbtests/dbhelper_tests.cpp
@@ -88,13 +88,15 @@ private:
     int _max;
 };
 
-class All : public Suite {
+class All : public OldStyleSuiteSpecification {
 public:
-    All() : Suite("remove") {}
+    All() : OldStyleSuiteSpecification("remove") {}
     void setupTests() {
         add<RemoveRange>();
     }
-} myall;
+};
+
+OldStyleSuiteInitializer<All> myall;
 
 }  // namespace
 }  // namespace mongo