From 8e0de1a8fa432f59dc934484bf26520d0ed2dfd9 Mon Sep 17 00:00:00 2001
From: Matt Dale <9760375+matthewdale@users.noreply.github.com>
Date: Thu, 16 Oct 2025 16:14:05 -0700
Subject: [PATCH] Remove the unused and dangerous ShareClient mtest option.

---
 internal/integration/mtest/mongotest.go | 28 +++++--------------------
 internal/integration/mtest/options.go   | 10 ---------
 2 files changed, 5 insertions(+), 33 deletions(-)

diff --git a/internal/integration/mtest/mongotest.go b/internal/integration/mtest/mongotest.go
index 07c67a4ce0..8978189583 100644
--- a/internal/integration/mtest/mongotest.go
+++ b/internal/integration/mtest/mongotest.go
@@ -82,7 +82,6 @@ type T struct {
 	clientType               ClientType
 	clientOpts               *options.ClientOptions
 	collOpts                 *options.CollectionOptionsBuilder
-	shareClient              *bool
 	allowFailPointsOnSharded bool
 
 	baseOpts *Options // used to create subtests
@@ -122,9 +121,6 @@ func newT(wrapped *testing.T, opts ...*Options) *T {
 
 	// create a set of base options for sub-tests
 	t.baseOpts = NewOptions().ClientOptions(t.clientOpts).CollectionOptions(t.collOpts).ClientType(t.clientType)
-	if t.shareClient != nil {
-		t.baseOpts.ShareClient(*t.shareClient)
-	}
 	if t.allowFailPointsOnSharded {
 		t.baseOpts.AllowFailPointsOnSharded()
 	}
@@ -143,12 +139,6 @@ func New(wrapped *testing.T, opts ...*Options) *T {
 
 	t := newT(wrapped, opts...)
 
-	// only create a client if it needs to be shared in sub-tests
-	// otherwise, a new client will be created for each subtest
-	if t.shareClient != nil && *t.shareClient {
-		t.createTestClient()
-	}
-
 	wrapped.Cleanup(t.cleanup)
 
 	return t
@@ -192,16 +182,10 @@ func (t *T) RunOpts(name string, opts *Options, callback func(mt *T)) {
 			sub.AddMockResponses(sub.mockResponses...)
 		}
 
-		// for shareClient, inherit the client from the parent
-		if sub.shareClient != nil && *sub.shareClient && sub.clientType == t.clientType {
-			sub.Client = t.Client
-		}
-		// only create a client if not already set
-		if sub.Client == nil {
-			if sub.createClient == nil || *sub.createClient {
-				sub.createTestClient()
-			}
+		if sub.createClient == nil || *sub.createClient {
+			sub.createTestClient()
 		}
+
 		// create a collection for this test
 		if sub.Client != nil {
 			sub.createTestCollection()
@@ -222,10 +206,8 @@ func (t *T) RunOpts(name string, opts *Options, callback func(mt *T)) {
 				sub.ClearFailPoints()
 				sub.ClearCollections()
 			}
-			// only disconnect client if it's not being shared
-			if sub.shareClient == nil || !*sub.shareClient {
-				_ = sub.Client.Disconnect(context.Background())
-			}
+
+			_ = sub.Client.Disconnect(context.Background())
 			assert.Equal(sub, 0, sessions, "%v sessions checked out", sessions)
 			assert.Equal(sub, 0, conns, "%v connections checked out", conns)
 		}()
diff --git a/internal/integration/mtest/options.go b/internal/integration/mtest/options.go
index 565983a3d1..1533bde0da 100644
--- a/internal/integration/mtest/options.go
+++ b/internal/integration/mtest/options.go
@@ -201,16 +201,6 @@ func (op *Options) CreateCollection(create bool) *Options {
 	return op
 }
 
-// ShareClient specifies whether or not a test should pass its client down to sub-tests. This should be set when calling
-// New() if the inheriting behavior is desired. This option must not be used if the test accesses command monitoring
-// events.
-func (op *Options) ShareClient(share bool) *Options {
-	op.optFuncs = append(op.optFuncs, func(t *T) {
-		t.shareClient = &share
-	})
-	return op
-}
-
 // CollectionName specifies the name for the collection for the test.
 func (op *Options) CollectionName(collName string) *Options {
 	op.optFuncs = append(op.optFuncs, func(t *T) {