Fix the erroneous runOnRequirements CSFLE disabled check in mtest.

Author: matthewdale

internal/integration/mtest/mongotest.go

@@ -802,10 +802,10 @@ func verifyRunOnBlockConstraint(rob RunOnBlock) error {
 	if rob.CSFLEEnabled() && rob.CSFLE.Options != nil {
 		return fmt.Errorf("auto encryption required (GODRIVER-3486)")
 	}
-
 	if rob.CSFLEEnabled() && !IsCSFLEEnabled() {
 		return fmt.Errorf("runOnBlock requires CSFLE to be enabled. Build with the cse tag to enable")
-	} else if !rob.CSFLEEnabled() && IsCSFLEEnabled() {
+	}
+	if rob.CSFLEDisabled() && IsCSFLEEnabled() {
 		return fmt.Errorf("runOnBlock requires CSFLE to be disabled. Build without the cse tag to disable")
 	}
 	if rob.CSFLEEnabled() {

internal/integration/mtest/options.go

@@ -100,10 +100,20 @@ type RunOnBlock struct {
 	CSFLE            *CSFLE                   `bson:"csfleConfiguration"`
 }
 
+// CSFLEEnabled returns true if CSFLE support is explicitly required in the
+// "runOnRequirement" block. It returns false if the CSFLE requirement is
+// unspecified or explicitly false.
 func (r *RunOnBlock) CSFLEEnabled() bool {
 	return r.CSFLE != nil && (r.CSFLE.Boolean || r.CSFLE.Options != nil)
 }
 
+// CSFLEDisabled returns true if CSFLE support is explicitly forbidden in the
+// "runOnRequirement" block. It returns false if the CSFLE requirement is
+// unspecified or explicitly true.
+func (r *RunOnBlock) CSFLEDisabled() bool {
+	return r.CSFLE != nil && !r.CSFLE.Boolean
+}
+
 // UnmarshalBSON implements custom BSON unmarshalling behavior for RunOnBlock because some test formats use the
 // "topology" key while the unified test format uses "topologies".
 func (r *RunOnBlock) UnmarshalBSON(data []byte) error {