SERVER-34798 Remove ServiceContext subclasses and use new ServiceContext in every unit test.

This patch does several loosely related and surprisingly hard to separate things.

1.) Make the ServiceContext class final

2.) Create a mechanism, called ConstructorActions, for running methods on
ServiceContexts immediately after they're built and immediately before they're
destroyed.

3.) Introduce / improve test fixture base classes for tests, giving them fresh
ServiceContext instances for each test case. There is one fixture for tests that
need a storage engine and another for those that do not.

4.) Make several remaining global variables SC decorations in support of (3)

5.) Replace many MONGO_INITIALIZERS that access getGlobalServiceContext with the
new constructor-actions system, which is needed for (3.)

6.) Fix up tests to use the fixtures from (3) and fix tests that silently used
different service contexts in together in a technically illegal fashion that now
breaks.

7.) Utilize (2) as necessary to simplify initialization of new ServiceContexts,
simplifying the fixtures in (3).

1 files changed, 15 insertions, 20 deletions

diff --git a/src/mongo/db/commands_test.cpp b/src/mongo/db/commands_test.cpp
index 0bec7ad4b51..2cdc620d0d9 100644
--- a/src/mongo/db/commands_test.cpp
+++ b/src/mongo/db/commands_test.cpp
@@ -32,7 +32,7 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/commands_test_example_gen.h"
 #include "mongo/db/dbmessage.h"
-#include "mongo/db/service_context_noop.h"
+#include "mongo/db/service_context_test_fixture.h"
 #include "mongo/unittest/unittest.h"
 
 namespace mongo {
@@ -96,14 +96,9 @@ TEST(Commands, appendCommandStatusErrorExtraInfo) {
     ASSERT_BSONOBJ_EQ(actualResult.obj(), expectedResult.obj());
 }
 
-class ParseNsOrUUID : public unittest::Test {
+class ParseNsOrUUID : public ServiceContextTest {
 public:
-    ParseNsOrUUID()
-        : client(service.makeClient("test")),
-          opCtxPtr(client->makeOperationContext()),
-          opCtx(opCtxPtr.get()) {}
-    ServiceContextNoop service;
-    ServiceContext::UniqueClient client;
+    ParseNsOrUUID() : opCtxPtr(makeOperationContext()), opCtx(opCtxPtr.get()) {}
     ServiceContext::UniqueOperationContext opCtxPtr;
     OperationContext* opCtx;
 };
@@ -333,18 +328,18 @@ ExampleMinimalCommand exampleMinimalCommand;
 ExampleVoidCommand exampleVoidCommand;
 CmdT<decltype(throwFn)> throwStatusCommand("throwsStatus", throwFn);
 
-struct IncrementTestCommon {
+class TypedCommand : public ServiceContextTest {
+protected:
     template <typename T>
-    void run(T& command, std::function<void(int, const BSONObj&)> postAssert) {
+    void runIncr(T& command, std::function<void(int, const BSONObj&)> postAssert) {
         const NamespaceString ns("testdb.coll");
-        auto client = getGlobalServiceContext()->makeClient("commands_test");
         for (std::int32_t i : {123, 12345, 0, -456}) {
             const OpMsgRequest request = [&] {
                 typename T::Request incr(ns);
                 incr.setI(i);
                 return incr.serialize(BSON("$db" << ns.db()));
             }();
-            auto opCtx = client->makeOperationContext();
+            auto opCtx = makeOperationContext();
             auto invocation = command.parse(opCtx.get(), request);
 
             ASSERT_EQ(invocation->ns(), ns);
@@ -368,29 +363,29 @@ struct IncrementTestCommon {
     }
 };
 
-TEST(TypedCommand, runTyped) {
-    IncrementTestCommon{}.run(exampleIncrementCommand, [](int i, const BSONObj& reply) {
+TEST_F(TypedCommand, runTyped) {
+    runIncr(exampleIncrementCommand, [](int i, const BSONObj& reply) {
         ASSERT_EQ(reply["ok"].Double(), 1.0);
         ASSERT_EQ(reply["iPlusOne"].Int(), i + 1);
     });
 }
 
-TEST(TypedCommand, runMinimal) {
-    IncrementTestCommon{}.run(exampleMinimalCommand, [](int i, const BSONObj& reply) {
+TEST_F(TypedCommand, runMinimal) {
+    runIncr(exampleMinimalCommand, [](int i, const BSONObj& reply) {
         ASSERT_EQ(reply["ok"].Double(), 1.0);
         ASSERT_EQ(reply["iPlusOne"].Int(), i + 1);
     });
 }
 
-TEST(TypedCommand, runVoid) {
-    IncrementTestCommon{}.run(exampleVoidCommand, [](int i, const BSONObj& reply) {
+TEST_F(TypedCommand, runVoid) {
+    runIncr(exampleVoidCommand, [](int i, const BSONObj& reply) {
         ASSERT_EQ(reply["ok"].Double(), 1.0);
         ASSERT_EQ(exampleVoidCommand.iCapture, i + 1);
     });
 }
 
-TEST(TypedCommand, runThrowStatus) {
-    IncrementTestCommon{}.run(throwStatusCommand, [](int i, const BSONObj& reply) {
+TEST_F(TypedCommand, runThrowStatus) {
+    runIncr(throwStatusCommand, [](int i, const BSONObj& reply) {
         Status status = Status::OK();
         try {
             (void)throwFn();