diff --git a/src/coll/options.rs b/src/coll/options.rs
index cfc99ff04..8987eac0f 100644
--- a/src/coll/options.rs
+++ b/src/coll/options.rs
@@ -509,7 +509,7 @@ pub struct CountOptions {
     ///
     /// This options maps to the `maxTimeMS` MongoDB query option, so the duration will be sent
     /// across the wire as an integer number of milliseconds.
-    #[serde(deserialize_with = "deserialize_duration_from_u64_millis")]
+    #[serde(default, deserialize_with = "deserialize_duration_from_u64_millis")]
     pub max_time: Option<Duration>,
 
     /// The number of documents to skip before counting.
@@ -548,6 +548,7 @@ pub struct EstimatedDocumentCountOptions {
     /// This options maps to the `maxTimeMS` MongoDB query option, so the duration will be sent
     /// across the wire as an integer number of milliseconds.
     #[serde(
+        default,
         serialize_with = "serialize_duration_as_int_millis",
         rename = "maxTimeMS",
         deserialize_with = "deserialize_duration_from_u64_millis"
@@ -577,6 +578,7 @@ pub struct DistinctOptions {
     /// This options maps to the `maxTimeMS` MongoDB query option, so the duration will be sent
     /// across the wire as an integer number of milliseconds.
     #[serde(
+        default,
         serialize_with = "serialize_duration_as_int_millis",
         rename = "maxTimeMS",
         deserialize_with = "deserialize_duration_from_u64_millis"
diff --git a/src/error.rs b/src/error.rs
index c14d33a7b..c9463cde2 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,6 +1,10 @@
 //! Contains the `Error` and `Result` types that `mongodb` uses.
 
-use std::{collections::{HashMap, HashSet}, fmt::{self, Debug}, sync::Arc};
+use std::{
+    collections::{HashMap, HashSet},
+    fmt::{self, Debug},
+    sync::Arc,
+};
 
 use bson::Bson;
 use serde::Deserialize;
@@ -58,8 +62,7 @@ impl Error {
         ErrorKind::ConnectionPoolCleared {
             message: format!(
                 "Connection pool for {} cleared because another operation failed with: {}",
-                address,
-                cause
+                address, cause
             ),
         }
         .into()
diff --git a/src/is_master.rs b/src/is_master.rs
index 553a3824f..3f94c1060 100644
--- a/src/is_master.rs
+++ b/src/is_master.rs
@@ -14,7 +14,11 @@ use crate::{
 /// Construct an isMaster command.
 pub(crate) fn is_master_command(api: Option<&ServerApi>) -> Command {
     let command_name = if api.is_some() { "hello" } else { "isMaster" };
-    let mut command = Command::new(command_name.into(), "admin".into(), doc! { command_name: 1 });
+    let mut command = Command::new(
+        command_name.into(),
+        "admin".into(),
+        doc! { command_name: 1 },
+    );
     if let Some(server_api) = api {
         command.set_server_api(server_api);
     }
@@ -28,8 +32,8 @@ pub(crate) async fn run_is_master(
     command: Command,
     conn: &mut Connection,
 ) -> Result<IsMasterReply> {
-    if !command.name.eq_ignore_ascii_case("ismaster") &&
-        !command.name.eq_ignore_ascii_case("hello") {
+    if !command.name.eq_ignore_ascii_case("ismaster") && !command.name.eq_ignore_ascii_case("hello")
+    {
         return Err(ErrorKind::Internal {
             message: format!("invalid ismaster command: {}", command.name),
         }
diff --git a/src/results.rs b/src/results.rs
index e568f892b..e2d7292d9 100644
--- a/src/results.rs
+++ b/src/results.rs
@@ -147,7 +147,10 @@ pub struct DatabaseSpecification {
     pub name: String,
 
     /// The amount of disk space in bytes that is consumed by the database.
-    #[serde(deserialize_with = "crate::bson_util::deserialize_u64_from_bson_number")]
+    #[serde(
+        deserialize_with = "crate::bson_util::deserialize_u64_from_bson_number",
+        serialize_with = "crate::bson::serde_helpers::serialize_u64_as_i64"
+    )]
     pub size_on_disk: u64,
 
     /// Whether the database has any data.
diff --git a/src/test/mod.rs b/src/test/mod.rs
index d6f96b0f3..c09b39a11 100644
--- a/src/test/mod.rs
+++ b/src/test/mod.rs
@@ -11,7 +11,7 @@ mod spec;
 mod util;
 
 pub(crate) use self::{
-    spec::{run_spec_test, RunOn, Topology},
+    spec::{run_single_test, run_spec_test, RunOn, Topology},
     util::{
         assert_matches,
         CmapEvent,
diff --git a/src/test/spec/json/unified-runner-examples/example-insertOne.json b/src/test/spec/json/unified-test-format/examples/example-insertOne.json
similarity index 100%
rename from src/test/spec/json/unified-runner-examples/example-insertOne.json
rename to src/test/spec/json/unified-test-format/examples/example-insertOne.json
diff --git a/src/test/spec/json/unified-runner-examples/poc-crud.json b/src/test/spec/json/unified-test-format/examples/poc-crud.json
similarity index 100%
rename from src/test/spec/json/unified-runner-examples/poc-crud.json
rename to src/test/spec/json/unified-test-format/examples/poc-crud.json
diff --git a/src/test/spec/json/unified-runner-examples/poc-retryable-reads.json b/src/test/spec/json/unified-test-format/examples/poc-retryable-reads.json
similarity index 100%
rename from src/test/spec/json/unified-runner-examples/poc-retryable-reads.json
rename to src/test/spec/json/unified-test-format/examples/poc-retryable-reads.json
diff --git a/src/test/spec/json/unified-runner-examples/poc-retryable-writes.json b/src/test/spec/json/unified-test-format/examples/poc-retryable-writes.json
similarity index 100%
rename from src/test/spec/json/unified-runner-examples/poc-retryable-writes.json
rename to src/test/spec/json/unified-test-format/examples/poc-retryable-writes.json
diff --git a/src/test/spec/json/unified-runner-examples/poc-sessions.json b/src/test/spec/json/unified-test-format/examples/poc-sessions.json
similarity index 100%
rename from src/test/spec/json/unified-runner-examples/poc-sessions.json
rename to src/test/spec/json/unified-test-format/examples/poc-sessions.json
diff --git a/src/test/spec/json/unified-runner-examples/poc-sessions.yml b/src/test/spec/json/unified-test-format/examples/poc-sessions.yml
similarity index 100%
rename from src/test/spec/json/unified-runner-examples/poc-sessions.yml
rename to src/test/spec/json/unified-test-format/examples/poc-sessions.yml
diff --git a/src/test/spec/json/unified-runner-examples/poc-transactions.json b/src/test/spec/json/unified-test-format/examples/poc-transactions.json
similarity index 100%
rename from src/test/spec/json/unified-runner-examples/poc-transactions.json
rename to src/test/spec/json/unified-test-format/examples/poc-transactions.json
diff --git a/src/test/spec/json/unified-runner-examples/poc-transactions.yml b/src/test/spec/json/unified-test-format/examples/poc-transactions.yml
similarity index 100%
rename from src/test/spec/json/unified-runner-examples/poc-transactions.yml
rename to src/test/spec/json/unified-test-format/examples/poc-transactions.yml
diff --git a/src/test/spec/json/unified-test-format/valid-fail/assertNumberConnectionsCheckedOut.json b/src/test/spec/json/unified-test-format/valid-fail/assertNumberConnectionsCheckedOut.json
new file mode 100644
index 000000000..9799bb2f6
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/assertNumberConnectionsCheckedOut.json
@@ -0,0 +1,63 @@
+{
+  "description": "assertNumberConnectionsCheckedOut",
+  "schemaVersion": "1.3",
+  "createEntities": [
+    {
+      "client": {
+        "id": "client0",
+        "useMultipleMongoses": true
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "operation fails if client field is not specified",
+      "operations": [
+        {
+          "name": "assertNumberConnectionsCheckedOut",
+          "object": "testRunner",
+          "arguments": {
+            "connections": 1
+          }
+        }
+      ]
+    },
+    {
+      "description": "operation fails if connections field is not specified",
+      "operations": [
+        {
+          "name": "assertNumberConnectionsCheckedOut",
+          "object": "testRunner",
+          "arguments": {
+            "client": "client0"
+          }
+        }
+      ]
+    },
+    {
+      "description": "operation fails if client entity does not exist",
+      "operations": [
+        {
+          "name": "assertNumberConnectionsCheckedOut",
+          "object": "testRunner",
+          "arguments": {
+            "client": "client1"
+          }
+        }
+      ]
+    },
+    {
+      "description": "operation fails if number of connections is incorrect",
+      "operations": [
+        {
+          "name": "assertNumberConnectionsCheckedOut",
+          "object": "testRunner",
+          "arguments": {
+            "client": "client0",
+            "connections": 1
+          }
+        }
+      ]
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/assertNumberConnectionsCheckedOut.yml b/src/test/spec/json/unified-test-format/valid-fail/assertNumberConnectionsCheckedOut.yml
new file mode 100644
index 000000000..8a8aa6366
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/assertNumberConnectionsCheckedOut.yml
@@ -0,0 +1,38 @@
+description: assertNumberConnectionsCheckedOut
+
+schemaVersion: '1.3'
+
+createEntities:
+  - client:
+      id: &client0 client0
+      useMultipleMongoses: true
+
+tests:
+  - description: operation fails if client field is not specified
+    operations:
+      - name: assertNumberConnectionsCheckedOut
+        object: testRunner
+        arguments:
+          connections: 1
+
+  - description: operation fails if connections field is not specified
+    operations:
+      - name: assertNumberConnectionsCheckedOut
+        object: testRunner
+        arguments:
+          client: *client0
+
+  - description: operation fails if client entity does not exist
+    operations:
+      - name: assertNumberConnectionsCheckedOut
+        object: testRunner
+        arguments:
+          client: client1
+
+  - description: operation fails if number of connections is incorrect
+    operations:
+      - name: assertNumberConnectionsCheckedOut
+        object: testRunner
+        arguments:
+          client: *client0
+          connections: 1
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-bucket-database-undefined.json b/src/test/spec/json/unified-test-format/valid-fail/entity-bucket-database-undefined.json
new file mode 100644
index 000000000..7f7f1978c
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-bucket-database-undefined.json
@@ -0,0 +1,18 @@
+{
+  "description": "entity-bucket-database-undefined",
+  "schemaVersion": "1.0",
+  "createEntities": [
+    {
+      "bucket": {
+        "id": "bucket0",
+        "database": "foo"
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "foo",
+      "operations": []
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-bucket-database-undefined.yml b/src/test/spec/json/unified-test-format/valid-fail/entity-bucket-database-undefined.yml
new file mode 100644
index 000000000..7aeda8e1a
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-bucket-database-undefined.yml
@@ -0,0 +1,12 @@
+description: "entity-bucket-database-undefined"
+
+schemaVersion: "1.0"
+
+createEntities:
+  - bucket:
+      id: &bucket0 "bucket0"
+      database: "foo"
+
+tests:
+  - description: "foo"
+    operations: []
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-client-apiVersion-unsupported.json b/src/test/spec/json/unified-test-format/valid-fail/entity-client-apiVersion-unsupported.json
new file mode 100644
index 000000000..d92d23dca
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-client-apiVersion-unsupported.json
@@ -0,0 +1,20 @@
+{
+  "description": "entity-client-apiVersion-unsupported",
+  "schemaVersion": "1.1",
+  "createEntities": [
+    {
+      "client": {
+        "id": "client0",
+        "serverApi": {
+          "version": "server_will_never_support_this_api_version"
+        }
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "foo",
+      "operations": []
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-client-apiVersion-unsupported.yml b/src/test/spec/json/unified-test-format/valid-fail/entity-client-apiVersion-unsupported.yml
new file mode 100644
index 000000000..7c626a308
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-client-apiVersion-unsupported.yml
@@ -0,0 +1,13 @@
+description: "entity-client-apiVersion-unsupported"
+
+schemaVersion: "1.1"
+
+createEntities:
+  - client:
+      id: &client0 client0
+      serverApi:
+        version: "server_will_never_support_this_api_version"
+
+tests:
+  - description: "foo"
+    operations: []
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_with_client_id.json b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_with_client_id.json
new file mode 100644
index 000000000..8c0c4d204
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_with_client_id.json
@@ -0,0 +1,28 @@
+{
+  "description": "entity-client-storeEventsAsEntities-conflict_with_client_id",
+  "schemaVersion": "1.2",
+  "createEntities": [
+    {
+      "client": {
+        "id": "client0",
+        "storeEventsAsEntities": [
+          {
+            "id": "client0",
+            "events": [
+              "PoolCreatedEvent",
+              "PoolReadyEvent",
+              "PoolClearedEvent",
+              "PoolClosedEvent"
+            ]
+          }
+        ]
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "foo",
+      "operations": []
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_with_client_id.yml b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_with_client_id.yml
new file mode 100644
index 000000000..b7055c9db
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_with_client_id.yml
@@ -0,0 +1,16 @@
+description: "entity-client-storeEventsAsEntities-conflict_with_client_id"
+
+schemaVersion: "1.2"
+
+createEntities:
+  - client:
+      id: &client0 client0
+      storeEventsAsEntities:
+        # Using the client ID here will ensure that test runners also detect
+        # conflicts with the same entity being defined
+        - id: *client0
+          events: ["PoolCreatedEvent", "PoolReadyEvent", "PoolClearedEvent", "PoolClosedEvent"]
+
+tests:
+  - description: "foo"
+    operations: []
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_different_array.json b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_different_array.json
new file mode 100644
index 000000000..77bc4abf2
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_different_array.json
@@ -0,0 +1,43 @@
+{
+  "description": "entity-client-storeEventsAsEntities-conflict_within_different_array",
+  "schemaVersion": "1.2",
+  "createEntities": [
+    {
+      "client": {
+        "id": "client0",
+        "storeEventsAsEntities": [
+          {
+            "id": "events",
+            "events": [
+              "PoolCreatedEvent",
+              "PoolReadyEvent",
+              "PoolClearedEvent",
+              "PoolClosedEvent"
+            ]
+          }
+        ]
+      }
+    },
+    {
+      "client": {
+        "id": "client1",
+        "storeEventsAsEntities": [
+          {
+            "id": "events",
+            "events": [
+              "CommandStartedEvent",
+              "CommandSucceededEvent",
+              "CommandFailedEvent"
+            ]
+          }
+        ]
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "foo",
+      "operations": []
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_different_array.yml b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_different_array.yml
new file mode 100644
index 000000000..8836445c9
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_different_array.yml
@@ -0,0 +1,19 @@
+description: "entity-client-storeEventsAsEntities-conflict_within_different_array"
+
+schemaVersion: "1.2"
+
+createEntities:
+  - client:
+      id: &client0 client0
+      storeEventsAsEntities:
+        - id: &events events
+          events: ["PoolCreatedEvent", "PoolReadyEvent", "PoolClearedEvent", "PoolClosedEvent"]
+  - client:
+      id: &client1 client1
+      storeEventsAsEntities:
+        - id: *events
+          events: ["CommandStartedEvent", "CommandSucceededEvent", "CommandFailedEvent"]
+
+tests:
+  - description: "foo"
+    operations: []
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_same_array.json b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_same_array.json
new file mode 100644
index 000000000..e1a949988
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_same_array.json
@@ -0,0 +1,36 @@
+{
+  "description": "entity-client-storeEventsAsEntities-conflict_within_same_array",
+  "schemaVersion": "1.2",
+  "createEntities": [
+    {
+      "client": {
+        "id": "client0",
+        "storeEventsAsEntities": [
+          {
+            "id": "events",
+            "events": [
+              "PoolCreatedEvent",
+              "PoolReadyEvent",
+              "PoolClearedEvent",
+              "PoolClosedEvent"
+            ]
+          },
+          {
+            "id": "events",
+            "events": [
+              "CommandStartedEvent",
+              "CommandSucceededEvent",
+              "CommandFailedEvent"
+            ]
+          }
+        ]
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "foo",
+      "operations": []
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_same_array.yml b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_same_array.yml
new file mode 100644
index 000000000..25ee7400d
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-client-storeEventsAsEntities-conflict_within_same_array.yml
@@ -0,0 +1,16 @@
+description: "entity-client-storeEventsAsEntities-conflict_within_same_array"
+
+schemaVersion: "1.2"
+
+createEntities:
+  - client:
+      id: &client0 client0
+      storeEventsAsEntities:
+        - id: &events events
+          events: ["PoolCreatedEvent", "PoolReadyEvent", "PoolClearedEvent", "PoolClosedEvent"]
+        - id: *events
+          events: ["CommandStartedEvent", "CommandSucceededEvent", "CommandFailedEvent"]
+
+tests:
+  - description: "foo"
+    operations: []
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-collection-database-undefined.json b/src/test/spec/json/unified-test-format/valid-fail/entity-collection-database-undefined.json
new file mode 100644
index 000000000..20b0733e3
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-collection-database-undefined.json
@@ -0,0 +1,19 @@
+{
+  "description": "entity-collection-database-undefined",
+  "schemaVersion": "1.0",
+  "createEntities": [
+    {
+      "collection": {
+        "id": "collection0",
+        "database": "foo",
+        "collectionName": "foo"
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "foo",
+      "operations": []
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-collection-database-undefined.yml b/src/test/spec/json/unified-test-format/valid-fail/entity-collection-database-undefined.yml
new file mode 100644
index 000000000..a66b6ed29
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-collection-database-undefined.yml
@@ -0,0 +1,13 @@
+description: "entity-collection-database-undefined"
+
+schemaVersion: "1.0"
+
+createEntities:
+  - collection:
+      id: &collection0 "collection0"
+      database: "foo"
+      collectionName: "foo"
+
+tests:
+  - description: "foo"
+    operations: []
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-database-client-undefined.json b/src/test/spec/json/unified-test-format/valid-fail/entity-database-client-undefined.json
new file mode 100644
index 000000000..0f8110e6d
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-database-client-undefined.json
@@ -0,0 +1,19 @@
+{
+  "description": "entity-database-client-undefined",
+  "schemaVersion": "1.0",
+  "createEntities": [
+    {
+      "database": {
+        "id": "database0",
+        "client": "foo",
+        "databaseName": "foo"
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "foo",
+      "operations": []
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-database-client-undefined.yml b/src/test/spec/json/unified-test-format/valid-fail/entity-database-client-undefined.yml
new file mode 100644
index 000000000..34b58cece
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-database-client-undefined.yml
@@ -0,0 +1,13 @@
+description: "entity-database-client-undefined"
+
+schemaVersion: "1.0"
+
+createEntities:
+  - database:
+      id: &database0 "database0"
+      client: "foo"
+      databaseName: "foo"
+
+tests:
+  - description: "foo"
+    operations: []
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-find-cursor.json b/src/test/spec/json/unified-test-format/valid-fail/entity-find-cursor.json
new file mode 100644
index 000000000..f4c5bcdf4
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-find-cursor.json
@@ -0,0 +1,62 @@
+{
+  "description": "entity-find-cursor",
+  "schemaVersion": "1.3",
+  "createEntities": [
+    {
+      "client": {
+        "id": "client0"
+      }
+    },
+    {
+      "database": {
+        "id": "database0",
+        "client": "client0",
+        "databaseName": "database0Name"
+      }
+    },
+    {
+      "collection": {
+        "id": "collection0",
+        "database": "database0",
+        "collectionName": "coll0"
+      }
+    }
+  ],
+  "initialData": [
+    {
+      "databaseName": "database0Name",
+      "collectionName": "coll0",
+      "documents": []
+    }
+  ],
+  "tests": [
+    {
+      "description": "createFindCursor fails if filter is not specified",
+      "operations": [
+        {
+          "name": "createFindCursor",
+          "object": "collection0",
+          "saveResultAsEntity": "cursor0"
+        }
+      ]
+    },
+    {
+      "description": "iterateUntilDocumentOrError fails if it references a nonexistent entity",
+      "operations": [
+        {
+          "name": "iterateUntilDocumentOrError",
+          "object": "cursor0"
+        }
+      ]
+    },
+    {
+      "description": "close fails if it references a nonexistent entity",
+      "operations": [
+        {
+          "name": "close",
+          "object": "cursor0"
+        }
+      ]
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-find-cursor.yml b/src/test/spec/json/unified-test-format/valid-fail/entity-find-cursor.yml
new file mode 100644
index 000000000..ac35615fe
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-find-cursor.yml
@@ -0,0 +1,37 @@
+description: entity-find-cursor
+
+schemaVersion: '1.3'
+
+createEntities:
+  - client:
+      id: &client0 client0
+  - database:
+      id: &database0 database0
+      client: *client0
+      databaseName: &database0Name database0Name
+  - collection:
+      id: &collection0 collection0
+      database: *database0
+      collectionName: &collection0Name coll0
+
+initialData:
+  - databaseName: *database0Name
+    collectionName: *collection0Name
+    documents: []
+
+tests:
+  - description: createFindCursor fails if filter is not specified
+    operations:
+      - name: createFindCursor
+        object: *collection0
+        saveResultAsEntity: &cursor0 cursor0
+
+  - description: iterateUntilDocumentOrError fails if it references a nonexistent entity
+    operations:
+      - name: iterateUntilDocumentOrError
+        object: cursor0
+
+  - description: close fails if it references a nonexistent entity
+    operations:
+      - name: close
+        object: cursor0
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-session-client-undefined.json b/src/test/spec/json/unified-test-format/valid-fail/entity-session-client-undefined.json
new file mode 100644
index 000000000..260356436
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-session-client-undefined.json
@@ -0,0 +1,18 @@
+{
+  "description": "entity-session-client-undefined",
+  "schemaVersion": "1.0",
+  "createEntities": [
+    {
+      "session": {
+        "id": "session0",
+        "client": "foo"
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "foo",
+      "operations": []
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/entity-session-client-undefined.yml b/src/test/spec/json/unified-test-format/valid-fail/entity-session-client-undefined.yml
new file mode 100644
index 000000000..16eaea46b
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/entity-session-client-undefined.yml
@@ -0,0 +1,12 @@
+description: "entity-session-client-undefined"
+
+schemaVersion: "1.0"
+
+createEntities:
+  - session:
+      id: &session0 "session0"
+      client: "foo"
+
+tests:
+  - description: "foo"
+    operations: []
diff --git a/src/test/spec/json/unified-test-format/valid-fail/ignoreResultAndError.json b/src/test/spec/json/unified-test-format/valid-fail/ignoreResultAndError.json
new file mode 100644
index 000000000..4457040b4
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/ignoreResultAndError.json
@@ -0,0 +1,72 @@
+{
+  "description": "ignoreResultAndError",
+  "schemaVersion": "1.3",
+  "createEntities": [
+    {
+      "client": {
+        "id": "client0",
+        "useMultipleMongoses": true
+      }
+    },
+    {
+      "database": {
+        "id": "database0",
+        "client": "client0",
+        "databaseName": "database0Name"
+      }
+    },
+    {
+      "collection": {
+        "id": "collection0",
+        "database": "database0",
+        "collectionName": "coll0"
+      }
+    }
+  ],
+  "initialData": [
+    {
+      "collectionName": "coll0",
+      "databaseName": "database0Name",
+      "documents": []
+    }
+  ],
+  "tests": [
+    {
+      "description": "operation errors are not ignored if ignoreResultAndError is false",
+      "operations": [
+        {
+          "name": "insertOne",
+          "object": "collection0",
+          "arguments": {
+            "document": {
+              "_id": 1
+            }
+          }
+        },
+        {
+          "name": "insertOne",
+          "object": "collection0",
+          "arguments": {
+            "document": {
+              "_id": 1
+            }
+          },
+          "ignoreResultAndError": false
+        }
+      ]
+    },
+    {
+      "description": "malformed operation fails if ignoreResultAndError is true",
+      "operations": [
+        {
+          "name": "insertOne",
+          "object": "collection0",
+          "arguments": {
+            "foo": "bar"
+          },
+          "ignoreResultAndError": true
+        }
+      ]
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/ignoreResultAndError.yml b/src/test/spec/json/unified-test-format/valid-fail/ignoreResultAndError.yml
new file mode 100644
index 000000000..52498627a
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/ignoreResultAndError.yml
@@ -0,0 +1,43 @@
+description: ignoreResultAndError  
+
+schemaVersion: '1.3'
+
+createEntities:
+  - client:
+      id: &client0 client0
+      useMultipleMongoses: true
+  - database:
+      id: &database0 database0
+      client: *client0
+      databaseName: &database0Name database0Name
+  - collection:
+      id: &collection0 collection0
+      database: *database0
+      collectionName: &collection0Name coll0
+
+initialData:
+  - collectionName: *collection0Name
+    databaseName: *database0Name
+    documents: []
+
+tests:
+  - description: operation errors are not ignored if ignoreResultAndError is false
+    operations:
+      - name: insertOne
+        object: *collection0
+        arguments:
+          document: &insertDocument { _id: 1 }
+      - name: insertOne
+        object: *collection0
+        arguments:
+          # Insert the same document to force a DuplicateKey error.
+          document: *insertDocument
+        ignoreResultAndError: false
+
+  - description: malformed operation fails if ignoreResultAndError is true
+    operations:
+      - name: insertOne
+        object: *collection0
+        arguments:
+          foo: bar
+        ignoreResultAndError: true
diff --git a/src/test/spec/json/unified-test-format/valid-fail/operation-failure.json b/src/test/spec/json/unified-test-format/valid-fail/operation-failure.json
new file mode 100644
index 000000000..8f6cae152
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/operation-failure.json
@@ -0,0 +1,56 @@
+{
+  "description": "operation-failure",
+  "schemaVersion": "1.0",
+  "createEntities": [
+    {
+      "client": {
+        "id": "client0"
+      }
+    },
+    {
+      "database": {
+        "id": "database0",
+        "client": "client0",
+        "databaseName": "operation-failure"
+      }
+    },
+    {
+      "collection": {
+        "id": "collection0",
+        "database": "database0",
+        "collectionName": "coll0"
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "Unsupported command",
+      "operations": [
+        {
+          "name": "runCommand",
+          "object": "database0",
+          "arguments": {
+            "commandName": "unsupportedCommand",
+            "command": {
+              "unsupportedCommand": 1
+            }
+          }
+        }
+      ]
+    },
+    {
+      "description": "Unsupported query operator",
+      "operations": [
+        {
+          "name": "find",
+          "object": "collection0",
+          "arguments": {
+            "filter": {
+              "$unsupportedQueryOperator": 1
+            }
+          }
+        }
+      ]
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/operation-failure.yml b/src/test/spec/json/unified-test-format/valid-fail/operation-failure.yml
new file mode 100644
index 000000000..b80f7794d
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/operation-failure.yml
@@ -0,0 +1,31 @@
+description: "operation-failure"
+
+schemaVersion: "1.0"
+
+createEntities:
+  - client:
+      id: &client0 client0
+  - database:
+      id: &database0 database0
+      client: *client0
+      databaseName: operation-failure
+  - collection:
+      id: &collection0 collection0
+      database: *database0
+      collectionName: coll0
+
+tests:
+  - description: "Unsupported command"
+    operations:
+      - name: runCommand
+        object: *database0
+        arguments:
+          commandName: unsupportedCommand
+          command: { unsupportedCommand: 1 }
+
+  - description: "Unsupported query operator"
+    operations:
+      - name: find
+        object: *collection0
+        arguments:
+          filter: { $unsupportedQueryOperator: 1 }
diff --git a/src/test/spec/json/unified-test-format/valid-fail/returnDocument-enum-invalid.json b/src/test/spec/json/unified-test-format/valid-fail/returnDocument-enum-invalid.json
new file mode 100644
index 000000000..ea425fb56
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/returnDocument-enum-invalid.json
@@ -0,0 +1,66 @@
+{
+  "description": "returnDocument-enum-invalid",
+  "schemaVersion": "1.0",
+  "createEntities": [
+    {
+      "client": {
+        "id": "client0"
+      }
+    },
+    {
+      "database": {
+        "id": "database0",
+        "client": "client0",
+        "databaseName": "test"
+      }
+    },
+    {
+      "collection": {
+        "id": "collection0",
+        "database": "database0",
+        "collectionName": "coll"
+      }
+    }
+  ],
+  "tests": [
+    {
+      "description": "FindOneAndReplace returnDocument invalid enum value",
+      "operations": [
+        {
+          "name": "findOneAndReplace",
+          "object": "collection0",
+          "arguments": {
+            "filter": {
+              "_id": 1
+            },
+            "replacement": {
+              "_id": 1,
+              "x": 111
+            },
+            "returnDocument": "invalid"
+          }
+        }
+      ]
+    },
+    {
+      "description": "FindOneAndUpdate returnDocument invalid enum value",
+      "operations": [
+        {
+          "name": "findOneAndUpdate",
+          "object": "collection0",
+          "arguments": {
+            "filter": {
+              "_id": 1
+            },
+            "update": {
+              "$inc": {
+                "x": 1
+              }
+            },
+            "returnDocument": "invalid"
+          }
+        }
+      ]
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/returnDocument-enum-invalid.yml b/src/test/spec/json/unified-test-format/valid-fail/returnDocument-enum-invalid.yml
new file mode 100644
index 000000000..b877f5e96
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/returnDocument-enum-invalid.yml
@@ -0,0 +1,34 @@
+description: "returnDocument-enum-invalid"
+
+schemaVersion: "1.0"
+
+createEntities:
+  - client:
+      id: &client0 client0
+  - database:
+      id: &database0 database0
+      client: *client0
+      databaseName: &databaseName test
+  - collection:
+      id: &collection0 collection0
+      database: *database0
+      collectionName: &collectionName coll
+
+tests:
+  - description: "FindOneAndReplace returnDocument invalid enum value"
+    operations:
+      - name: findOneAndReplace
+        object: *collection0
+        arguments:
+          filter: { _id: 1 }
+          replacement: { _id: 1, x: 111 }
+          returnDocument: invalid
+
+  - description: "FindOneAndUpdate returnDocument invalid enum value"
+    operations:
+      - name: findOneAndUpdate
+        object: *collection0
+        arguments:
+          filter: { _id: 1 }
+          update: { $inc: { x : 1 }}
+          returnDocument: invalid
diff --git a/src/test/spec/json/unified-test-format/valid-fail/schemaVersion-unsupported.json b/src/test/spec/json/unified-test-format/valid-fail/schemaVersion-unsupported.json
new file mode 100644
index 000000000..ceb553291
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/schemaVersion-unsupported.json
@@ -0,0 +1,10 @@
+{
+  "description": "schemaVersion-unsupported",
+  "schemaVersion": "0.1",
+  "tests": [
+    {
+      "description": "foo",
+      "operations": []
+    }
+  ]
+}
diff --git a/src/test/spec/json/unified-test-format/valid-fail/schemaVersion-unsupported.yml b/src/test/spec/json/unified-test-format/valid-fail/schemaVersion-unsupported.yml
new file mode 100644
index 000000000..0cb6994d2
--- /dev/null
+++ b/src/test/spec/json/unified-test-format/valid-fail/schemaVersion-unsupported.yml
@@ -0,0 +1,7 @@
+description: "schemaVersion-unsupported"
+
+schemaVersion: "0.1"
+
+tests:
+  - description: "foo"
+    operations: []
diff --git a/src/test/spec/mod.rs b/src/test/spec/mod.rs
index 4c53f5f1f..d854f1f04 100644
--- a/src/test/spec/mod.rs
+++ b/src/test/spec/mod.rs
@@ -62,22 +62,26 @@ where
         }
 
         let test_file_full_path = base_path.join(&test_file_path);
-        let json: Value =
-            serde_json::from_reader(File::open(test_file_full_path.as_path()).unwrap()).unwrap();
+        run_single_test(test_file_full_path, &run_test_file).await;
+    }
+}
 
-        // Printing the name of the test file makes it easier to debug deserialization errors.
-        println!(
-            "Running tests from {}",
-            test_file_full_path.display().to_string()
-        );
+pub(crate) async fn run_single_test<T, F, G>(path: PathBuf, run_test_file: &F)
+where
+    F: Fn(T) -> G,
+    G: Future<Output = ()>,
+    T: DeserializeOwned,
+{
+    let json: Value = serde_json::from_reader(File::open(path.as_path()).unwrap()).unwrap();
 
-        run_test_file(
-            bson::from_bson(
-                Bson::try_from(json)
-                    .unwrap_or_else(|_| panic!("{}", test_file_full_path.display().to_string())),
-            )
-            .unwrap_or_else(|e| panic!("{}: {}", test_file_full_path.display().to_string(), e)),
+    // Printing the name of the test file makes it easier to debug deserialization errors.
+    println!("Running tests from {}", path.display().to_string());
+
+    run_test_file(
+        bson::from_bson(
+            Bson::try_from(json).unwrap_or_else(|_| panic!("{}", path.display().to_string())),
         )
-        .await
-    }
+        .unwrap_or_else(|e| panic!("{}: {}", path.display().to_string(), e)),
+    )
+    .await
 }
diff --git a/src/test/spec/unified_runner/mod.rs b/src/test/spec/unified_runner/mod.rs
index 2f23d33e3..4c3277624 100644
--- a/src/test/spec/unified_runner/mod.rs
+++ b/src/test/spec/unified_runner/mod.rs
@@ -5,16 +5,16 @@ mod test_event;
 mod test_file;
 mod test_runner;
 
-use std::time::Duration;
+use std::{fs::read_dir, path::PathBuf, time::Duration};
 
-use futures::stream::TryStreamExt;
+use futures::{future::FutureExt, stream::TryStreamExt};
 use semver::Version;
 use tokio::sync::RwLockWriteGuard;
 
 use crate::{
     bson::{doc, Document},
     options::{CollectionOptions, FindOptions, ReadConcern, ReadPreference, SelectionCriteria},
-    test::{run_spec_test, LOCK},
+    test::{run_single_test, run_spec_test, LOCK},
     RUNTIME,
 };
 
@@ -165,40 +165,41 @@ pub async fn run_unified_format_test(test_file: TestFile) {
                         }
                     }
 
-                    if let Some(ref expect_result) = operation.expect_result {
-                        let result = result
-                            .unwrap_or_else(|e| {
-                                panic!(
-                                    "{} should succeed, but the following error: {}",
-                                    operation.name, e
-                                )
-                            })
-                            .unwrap_or_else(|| {
+                    if let Some(expect_error) = operation.expect_error {
+                        let error = result
+                            .expect_err(&format!("{} should return an error", operation.name));
+                        expect_error.verify_result(error);
+                    } else {
+                        let result = result.unwrap_or_else(|e| {
+                            panic!(
+                                "{} should succeed, but the following error: {}",
+                                operation.name, e
+                            )
+                        });
+                        if let Some(ref expect_result) = operation.expect_result {
+                            let result = result.unwrap_or_else(|| {
                                 panic!("{} should return an entity", operation.name)
                             });
-                        match result {
-                            Entity::Bson(ref result) => {
-                                assert!(
-                                    results_match(
-                                        Some(result),
+                            match result {
+                                Entity::Bson(ref result) => {
+                                    assert!(
+                                        results_match(
+                                            Some(result),
+                                            expect_result,
+                                            operation.returns_root_documents(),
+                                            Some(&test_runner.entities),
+                                        ),
+                                        "result mismatch, expected = {:#?}  actual = {:#?}",
                                         expect_result,
-                                        operation.returns_root_documents(),
-                                        Some(&test_runner.entities),
-                                    ),
-                                    "result mismatch, expected = {:#?}  actual = {:#?}",
-                                    expect_result,
-                                    result
-                                );
+                                        result
+                                    );
+                                }
+                                _ => panic!(
+                                    "Incorrect entity type returned from {}, expected BSON",
+                                    operation.name
+                                ),
                             }
-                            _ => panic!(
-                                "Incorrect entity type returned from {}, expected BSON",
-                                operation.name
-                            ),
                         }
-                    } else if let Some(expect_error) = operation.expect_error {
-                        let error = result
-                            .expect_err(&format!("{} should return an error", operation.name));
-                        expect_error.verify_result(error);
                     }
                 }
             }
@@ -272,5 +273,38 @@ pub async fn run_unified_format_test(test_file: TestFile) {
 #[cfg_attr(feature = "async-std-runtime", async_std::test)]
 async fn test_examples() {
     let _guard: RwLockWriteGuard<_> = LOCK.run_exclusively().await;
-    run_spec_test(&["unified-runner-examples"], run_unified_format_test).await;
+    run_spec_test(
+        &["unified-test-format", "examples"],
+        run_unified_format_test,
+    )
+    .await;
+}
+
+#[cfg_attr(feature = "tokio-runtime", tokio::test(flavor = "multi_thread"))]
+#[cfg_attr(feature = "async-std-runtime", async_std::test)]
+async fn valid_fail() {
+    let _guard: RwLockWriteGuard<_> = LOCK.run_exclusively().await;
+
+    let path: PathBuf = [
+        env!("CARGO_MANIFEST_DIR"),
+        "src",
+        "test",
+        "spec",
+        "json",
+        "unified-test-format",
+        "valid-fail",
+    ]
+    .iter()
+    .collect();
+
+    for entry in read_dir(&path).unwrap() {
+        let test_file_path = PathBuf::from(entry.unwrap().file_name());
+        let path = path.join(&test_file_path);
+        let path_display = path.display().to_string();
+
+        std::panic::AssertUnwindSafe(run_single_test(path, &run_unified_format_test))
+            .catch_unwind()
+            .await
+            .expect_err(&format!("tests from {} should have failed", path_display));
+    }
 }
diff --git a/src/test/spec/unified_runner/operation.rs b/src/test/spec/unified_runner/operation.rs
index 96524a192..ae667d4ba 100644
--- a/src/test/spec/unified_runner/operation.rs
+++ b/src/test/spec/unified_runner/operation.rs
@@ -246,7 +246,7 @@ impl Deref for Operation {
 pub(super) struct DeleteMany {
     filter: Document,
     #[serde(flatten)]
-    options: Option<DeleteOptions>,
+    options: DeleteOptions,
 }
 
 #[async_trait]
@@ -274,7 +274,7 @@ impl TestOperation for DeleteMany {
 pub(super) struct DeleteOne {
     filter: Document,
     #[serde(flatten)]
-    options: Option<DeleteOptions>,
+    options: DeleteOptions,
 }
 
 #[async_trait]
@@ -302,7 +302,7 @@ impl TestOperation for DeleteOne {
 pub(super) struct Find {
     filter: Option<Document>,
     #[serde(flatten)]
-    options: Option<FindOptions>,
+    options: FindOptions,
 }
 
 #[async_trait]
@@ -334,7 +334,7 @@ impl TestOperation for Find {
 pub(super) struct InsertMany {
     documents: Vec<Document>,
     #[serde(flatten)]
-    options: Option<InsertManyOptions>,
+    options: InsertManyOptions,
 }
 
 #[async_trait]
@@ -368,7 +368,7 @@ pub(super) struct InsertOne {
     document: Document,
     session: Option<String>,
     #[serde(flatten)]
-    options: Option<InsertOneOptions>,
+    options: InsertOneOptions,
 }
 
 #[async_trait]
@@ -410,7 +410,7 @@ pub(super) struct UpdateMany {
     filter: Document,
     update: UpdateModifications,
     #[serde(flatten)]
-    options: Option<UpdateOptions>,
+    options: UpdateOptions,
 }
 
 #[async_trait]
@@ -443,7 +443,7 @@ pub(super) struct UpdateOne {
     filter: Document,
     update: UpdateModifications,
     #[serde(flatten)]
-    options: Option<UpdateOptions>,
+    options: UpdateOptions,
     session: Option<String>,
 }
 
@@ -490,7 +490,7 @@ impl TestOperation for UpdateOne {
 pub(super) struct Aggregate {
     pipeline: Vec<Document>,
     #[serde(flatten)]
-    options: Option<AggregateOptions>,
+    options: AggregateOptions,
 }
 
 #[async_trait]
@@ -531,7 +531,7 @@ pub(super) struct Distinct {
     field_name: String,
     filter: Option<Document>,
     #[serde(flatten)]
-    options: Option<DistinctOptions>,
+    options: DistinctOptions,
 }
 
 #[async_trait]
@@ -558,7 +558,7 @@ impl TestOperation for Distinct {
 pub(super) struct CountDocuments {
     filter: Document,
     #[serde(flatten)]
-    options: Option<CountOptions>,
+    options: CountOptions,
 }
 
 #[async_trait]
@@ -584,7 +584,7 @@ impl TestOperation for CountDocuments {
 #[serde(rename_all = "camelCase", deny_unknown_fields)]
 pub(super) struct EstimatedDocumentCount {
     #[serde(flatten)]
-    options: Option<EstimatedDocumentCountOptions>,
+    options: EstimatedDocumentCountOptions,
 }
 
 #[async_trait]
@@ -611,7 +611,7 @@ impl TestOperation for EstimatedDocumentCount {
 pub(super) struct FindOne {
     filter: Option<Document>,
     #[serde(flatten)]
-    options: Option<FindOneOptions>,
+    options: FindOneOptions,
 }
 
 #[async_trait]
@@ -641,7 +641,7 @@ impl TestOperation for FindOne {
 pub(super) struct ListDatabases {
     filter: Option<Document>,
     #[serde(flatten)]
-    options: Option<ListDatabasesOptions>,
+    options: ListDatabasesOptions,
 }
 
 #[async_trait]
@@ -668,7 +668,7 @@ impl TestOperation for ListDatabases {
 pub(super) struct ListDatabaseNames {
     filter: Option<Document>,
     #[serde(flatten)]
-    options: Option<ListDatabasesOptions>,
+    options: ListDatabasesOptions,
 }
 
 #[async_trait]
@@ -696,7 +696,7 @@ impl TestOperation for ListDatabaseNames {
 pub(super) struct ListCollections {
     filter: Option<Document>,
     #[serde(flatten)]
-    options: Option<ListCollectionsOptions>,
+    options: ListCollectionsOptions,
 }
 
 #[async_trait]
@@ -753,7 +753,7 @@ pub(super) struct ReplaceOne {
     filter: Document,
     replacement: Document,
     #[serde(flatten)]
-    options: Option<ReplaceOptions>,
+    options: ReplaceOptions,
 }
 
 #[async_trait]
@@ -786,7 +786,7 @@ pub(super) struct FindOneAndUpdate {
     filter: Document,
     update: UpdateModifications,
     #[serde(flatten)]
-    options: Option<FindOneAndUpdateOptions>,
+    options: FindOneAndUpdateOptions,
 }
 
 #[async_trait]
@@ -819,7 +819,7 @@ pub(super) struct FindOneAndReplace {
     filter: Document,
     replacement: Document,
     #[serde(flatten)]
-    options: Option<FindOneAndReplaceOptions>,
+    options: FindOneAndReplaceOptions,
 }
 
 #[async_trait]
@@ -851,7 +851,7 @@ impl TestOperation for FindOneAndReplace {
 pub(super) struct FindOneAndDelete {
     filter: Document,
     #[serde(flatten)]
-    options: Option<FindOneAndDeleteOptions>,
+    options: FindOneAndDeleteOptions,
 }
 
 #[async_trait]
@@ -956,7 +956,7 @@ impl TestOperation for AssertCollectionNotExists {
 pub(super) struct CreateCollection {
     collection: String,
     #[serde(flatten)]
-    options: Option<CreateCollectionOptions>,
+    options: CreateCollectionOptions,
     session: Option<String>,
 }
 
@@ -995,7 +995,7 @@ impl TestOperation for CreateCollection {
 pub(super) struct DropCollection {
     collection: String,
     #[serde(flatten)]
-    options: Option<DropCollectionOptions>,
+    options: DropCollectionOptions,
     session: Option<String>,
 }