diff --git a/Taskfile.yml b/Taskfile.yml
index a4c6f405bf..411a09366c 100644
--- a/Taskfile.yml
+++ b/Taskfile.yml
@@ -10,7 +10,7 @@ dotenv: ['.test.env']
 tasks:
 
   ### Utility tasks. ###
-  default: 
+  default:
     deps: [build, check-license, check-fmt, check-modules, lint, test-short]
 
   add-license: bash etc/check_license.sh -a
@@ -36,7 +36,7 @@ tasks:
 
   build-aws-ecs-test: go test -c ./internal/test/aws -o aws.testbin
 
-  cross-compile: 
+  cross-compile:
     - GOOS=linux GOARCH=386 go build ./...
     - GOOS=linux GOARCH=arm go build ./...
     - GOOS=linux GOARCH=arm64 go build ./...
@@ -44,7 +44,7 @@ tasks:
     - GOOS=linux GOARCH=ppc64le go build ./...
     - GOOS=linux GOARCH=s390x go build ./...
 
-  check-fmt: 
+  check-fmt:
     deps: [install-lll]
     cmds:
       - bash etc/check_fmt.sh
@@ -57,9 +57,9 @@ tasks:
 
   api-report: bash etc/api_report.sh
 
-  install-libmongocrypt: 
+  install-libmongocrypt:
     cmds: [bash etc/install-libmongocrypt.sh]
-    status: 
+    status:
       - test -d install || test -d /cygdrive/c/libmongocrypt/bin
 
   run-docker: bash etc/run_docker.sh
@@ -76,7 +76,7 @@ tasks:
   # specific operating systems or architectures. For example, staticcheck will only check for 64-bit
   # alignment of atomically accessed variables on 32-bit architectures (see
   # https://staticcheck.io/docs/checks#SA1027)
-  lint: 
+  lint:
     cmds:
       - GOOS=linux GOARCH=386 etc/golangci-lint.sh
       - GOOS=linux GOARCH=arm etc/golangci-lint.sh
@@ -104,8 +104,8 @@ tasks:
 
   test-oidc-remote: bash etc/run-oidc-remote-test.sh
 
-  test-atlas-connect: 
-    - go test -v -run ^TestAtlas$ go.mongodb.org/mongo-driver/v2/internal/cmd/testatlas -args "$ATLAS_REPL" "$ATLAS_SHRD" "$ATLAS_FREE" "$ATLAS_TLS11" "$ATLAS_TLS12" "$ATLAS_SERVERLESS" "$ATLAS_SRV_REPL" "$ATLAS_SRV_SHRD" "$ATLAS_SRV_FREE" "$ATLAS_SRV_TLS11" "$ATLAS_SRV_TLS12" "$ATLAS_SRV_SERVERLESS" >> test.suite
+  test-atlas-connect:
+    - go test -v -run ^TestAtlas$ go.mongodb.org/mongo-driver/v2/internal/cmd/testatlas -tags atlastest >> test.suite
 
   test-awskms: bash etc/run-awskms-test.sh
 
@@ -117,9 +117,9 @@ tasks:
 
   ### Local FaaS tasks. ###
   build-faas-awslambda:
-    requires: 
+    requires:
       vars: [MONGODB_URI]
-    cmds: 
+    cmds:
       - make -c internal/cmd/faas/awslambda
 
   ### Evergreen specific tasks. ###
@@ -134,7 +134,7 @@ tasks:
     - ATLAS_DATA_LAKE_INTEGRATION_TEST=true go test -v ./internal/integration/unified -run TestUnifiedSpec/atlas-data-lake-testing >> spec_test.suite
     - ATLAS_DATA_LAKE_INTEGRATION_TEST=true go test -v ./internal/integration -run TestAtlasDataLake >> spec_test.suite
 
-  evg-test-enterprise-auth: 
+  evg-test-enterprise-auth:
     - go run -tags gssapi ./internal/cmd/testentauth/main.go
 
   evg-test-oidc-auth:
@@ -188,15 +188,15 @@ tasks:
   ### Benchmark specific tasks and support. ###
   benchmark:
     deps: [perf-files]
-    cmds: 
+    cmds:
       - go test ${BUILD_TAGS} -benchmem -bench=. ./benchmark | test benchmark.suite
 
-  driver-benchmark: 
-    cmds: 
+  driver-benchmark:
+    cmds:
       - go test ./internal/cmd/benchmark -v --fullRun | tee perf.suite
 
   ### Internal tasks. ###
-  install-lll: 
+  install-lll:
     internal: true
     cmds:
       - go install github.com/walle/lll/...@latest
diff --git a/internal/assert/assertions.go b/internal/assert/assertions.go
index c227d47c83..0754a411a1 100644
--- a/internal/assert/assertions.go
+++ b/internal/assert/assertions.go
@@ -1073,3 +1073,20 @@ func buildErrorChainString(err error) string {
 	}
 	return chain
 }
+
+// NotEmpty asserts that the specified object is NOT [Empty].
+//
+//	if assert.NotEmpty(t, obj) {
+//	  assert.Equal(t, "two", obj[1])
+//	}
+func NotEmpty(t TestingT, object interface{}, msgAndArgs ...interface{}) bool {
+	pass := !isEmpty(object)
+	if !pass {
+		if h, ok := t.(tHelper); ok {
+			h.Helper()
+		}
+		Fail(t, fmt.Sprintf("Should NOT be empty, but was %v", object), msgAndArgs...)
+	}
+
+	return pass
+}
diff --git a/internal/cmd/testatlas/atlas_test.go b/internal/cmd/testatlas/atlas_test.go
index cf4a84735f..74707276b0 100644
--- a/internal/cmd/testatlas/atlas_test.go
+++ b/internal/cmd/testatlas/atlas_test.go
@@ -4,60 +4,166 @@
 // not use this file except in compliance with the License. You may obtain
 // a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
 
+//go:build atlastest
+// +build atlastest
+
 package main
 
 import (
 	"context"
+	"crypto/tls"
+	"encoding/base64"
 	"errors"
-	"flag"
 	"fmt"
+	"net/url"
 	"os"
+	"path/filepath"
 	"testing"
 	"time"
 
 	"go.mongodb.org/mongo-driver/v2/bson"
+	"go.mongodb.org/mongo-driver/v2/internal/assert"
 	"go.mongodb.org/mongo-driver/v2/internal/handshake"
+	"go.mongodb.org/mongo-driver/v2/internal/require"
 	"go.mongodb.org/mongo-driver/v2/mongo"
 	"go.mongodb.org/mongo-driver/v2/mongo/options"
 )
 
-func TestMain(m *testing.M) {
-	flag.Parse()
-	os.Exit(m.Run())
-}
-
 func TestAtlas(t *testing.T) {
-	uris := flag.Args()
-	ctx := context.Background()
-
-	t.Logf("Running atlas tests for %d uris\n", len(uris))
-
-	for idx, uri := range uris {
-		t.Logf("Running test %d\n", idx)
-
-		// Set a low server selection timeout so we fail fast if there are errors.
-		clientOpts := options.Client().
-			ApplyURI(uri).
-			SetServerSelectionTimeout(1 * time.Second)
-
-		// Run basic connectivity test.
-		if err := runTest(ctx, clientOpts); err != nil {
-			t.Fatalf("error running test with TLS at index %d: %v", idx, err)
-		}
-
-		tlsConfigSkipVerify := clientOpts.TLSConfig
-		tlsConfigSkipVerify.InsecureSkipVerify = true
-
-		// Run the connectivity test with InsecureSkipVerify to ensure SNI is done correctly even if verification is
-		// disabled.
-		clientOpts.SetTLSConfig(tlsConfigSkipVerify)
-
-		if err := runTest(ctx, clientOpts); err != nil {
-			t.Fatalf("error running test with tlsInsecure at index %d: %v", idx, err)
-		}
+	cases := []struct {
+		name        string
+		envVar      string
+		certKeyFile string
+		wantErr     string
+	}{
+		{
+			name:        "Atlas with TLS",
+			envVar:      "ATLAS_REPL",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with TLS and shared cluster",
+			envVar:      "ATLAS_SHRD",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with free tier",
+			envVar:      "ATLAS_FREE",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with TLS 1.1",
+			envVar:      "ATLAS_TLS11",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with TLS 1.2",
+			envVar:      "ATLAS_TLS12",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with serverless",
+			envVar:      "ATLAS_SERVERLESS",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with srv file on replica set",
+			envVar:      "ATLAS_SRV_REPL",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with srv file on shared cluster",
+			envVar:      "ATLAS_SRV_SHRD",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with srv file on free tier",
+			envVar:      "ATLAS_SRV_FREE",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with srv file on TLS 1.1",
+			envVar:      "ATLAS_SRV_TLS11",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with srv file on TLS 1.2",
+			envVar:      "ATLAS_SRV_TLS12",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with srv file on serverless",
+			envVar:      "ATLAS_SRV_SERVERLESS",
+			certKeyFile: "",
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with X509 Dev",
+			envVar:      "ATLAS_X509_DEV",
+			certKeyFile: createAtlasX509DevCertKeyFile(t),
+			wantErr:     "",
+		},
+		{
+			name:        "Atlas with X509 Dev no user",
+			envVar:      "ATLAS_X509_DEV",
+			certKeyFile: createAtlasX509DevCertKeyFileNoUser(t),
+			wantErr:     "UserNotFound",
+		},
 	}
 
-	t.Logf("Finished!")
+	for _, tc := range cases {
+		t.Run(fmt.Sprintf("%s (%s)", tc.name, tc.envVar), func(t *testing.T) {
+			uri := os.Getenv(tc.envVar)
+			require.NotEmpty(t, uri, "Environment variable %s is not set", tc.envVar)
+
+			if tc.certKeyFile != "" {
+				uri = addTLSCertKeyFile(t, tc.certKeyFile, uri)
+			}
+
+			// Set a low server selection timeout so we fail fast if there are errors.
+			clientOpts := options.Client().
+				ApplyURI(uri).
+				SetServerSelectionTimeout(1 * time.Second)
+
+			// Run basic connectivity test.
+			err := runTest(context.Background(), clientOpts)
+			if tc.wantErr != "" {
+				assert.ErrorContains(t, err, tc.wantErr, "expected error to contain %q", tc.wantErr)
+
+				return
+			}
+			require.NoError(t, err, "error running test with TLS")
+
+			orig := clientOpts.TLSConfig
+			if orig == nil {
+				orig = &tls.Config{}
+			}
+
+			insecure := orig.Clone()
+			insecure.InsecureSkipVerify = true
+
+			// Run the connectivity test with InsecureSkipVerify to ensure SNI is done
+			// correctly even if verification is disabled.
+			insecureClientOpts := options.Client().
+				ApplyURI(uri).
+				SetServerSelectionTimeout(1 * time.Second).
+				SetTLSConfig(insecure)
+
+			err = runTest(context.Background(), insecureClientOpts)
+			require.NoError(t, err, "error running test with tlsInsecure")
+		})
+	}
 }
 
 func runTest(ctx context.Context, clientOpts *options.ClientOptions) error {
@@ -83,3 +189,51 @@ func runTest(ctx context.Context, clientOpts *options.ClientOptions) error {
 	}
 	return nil
 }
+
+func createAtlasX509DevCertKeyFile(t *testing.T) string {
+	t.Helper()
+
+	b64 := os.Getenv("ATLAS_X509_DEV_CERT_BASE64")
+	assert.NotEmpty(t, b64, "Environment variable ATLAS_X509_DEV_CERT_BASE64 is not set")
+
+	certBytes, err := base64.StdEncoding.DecodeString(b64)
+	require.NoError(t, err, "failed to decode ATLAS_X509_DEV_CERT_BASE64")
+
+	certFilePath := filepath.Join(t.TempDir(), "atlas_x509_dev_cert.pem")
+
+	err = os.WriteFile(certFilePath, certBytes, 0600)
+	require.NoError(t, err, "failed to write ATLAS_X509_DEV_CERT_BASE64 to file")
+
+	return certFilePath
+}
+
+func createAtlasX509DevCertKeyFileNoUser(t *testing.T) string {
+	t.Helper()
+
+	b64 := os.Getenv("ATLAS_X509_DEV_CERT_NOUSER_BASE64")
+	assert.NotEmpty(t, b64, "Environment variable ATLAS_X509_DEV_CERT_NOUSER_BASE64 is not set")
+
+	keyBytes, err := base64.StdEncoding.DecodeString(b64)
+	require.NoError(t, err, "failed to decode ATLAS_X509_DEV_CERT_NOUSER_BASE64")
+
+	keyFilePath := filepath.Join(t.TempDir(), "atlas_x509_dev_cert_no_user.pem")
+
+	err = os.WriteFile(keyFilePath, keyBytes, 0600)
+	require.NoError(t, err, "failed to write ATLAS_X509_DEV_CERT_NOUSER_BASE64 to file")
+
+	return keyFilePath
+}
+
+func addTLSCertKeyFile(t *testing.T, certKeyFile, uri string) string {
+	t.Helper()
+
+	u, err := url.Parse(uri)
+	require.NoError(t, err, "failed to parse uri")
+
+	q := u.Query()
+	q.Set("tlsCertificateKeyFile", filepath.ToSlash(certKeyFile))
+
+	u.RawQuery = q.Encode()
+
+	return u.String()
+}
diff --git a/internal/require/require.go b/internal/require/require.go
index 26d1885759..0b60613e3e 100644
--- a/internal/require/require.go
+++ b/internal/require/require.go
@@ -817,3 +817,18 @@ func WithinDurationf(t TestingT, expected time.Time, actual time.Time, delta tim
 	}
 	t.FailNow()
 }
+
+// NotEmpty asserts that the specified object is NOT [Empty].
+//
+//	if require.NotEmpty(t, obj) {
+//	  require.Equal(t, "two", obj[1])
+//	}
+func NotEmpty(t TestingT, object interface{}, msgAndArgs ...interface{}) {
+	if h, ok := t.(tHelper); ok {
+		h.Helper()
+	}
+	if assert.NotEmpty(t, object, msgAndArgs...) {
+		return
+	}
+	t.FailNow()
+}