diff --git a/datafusion/ffi/src/execution_plan.rs b/datafusion/ffi/src/execution_plan.rs
index 8087acfa33c8..00602474d621 100644
--- a/datafusion/ffi/src/execution_plan.rs
+++ b/datafusion/ffi/src/execution_plan.rs
@@ -219,17 +219,17 @@ impl TryFrom<&FFI_ExecutionPlan> for ForeignExecutionPlan {
             let properties: PlanProperties = (plan.properties)(plan).try_into()?;
 
             let children_rvec = (plan.children)(plan);
-            let children: Result<Vec<_>> = children_rvec
+            let children = children_rvec
                 .iter()
                 .map(ForeignExecutionPlan::try_from)
                 .map(|child| child.map(|c| Arc::new(c) as Arc<dyn ExecutionPlan>))
-                .collect();
+                .collect::<Result<Vec<_>>>()?;
 
             Ok(Self {
                 name,
                 plan: plan.clone(),
                 properties,
-                children: children?,
+                children,
             })
         }
     }
@@ -281,6 +281,7 @@ impl ExecutionPlan for ForeignExecutionPlan {
 
 #[cfg(test)]
 mod tests {
+    use arrow::datatypes::{DataType, Field, Schema};
     use datafusion::{
         physical_plan::{
             execution_plan::{Boundedness, EmissionType},
@@ -294,6 +295,7 @@ mod tests {
     #[derive(Debug)]
     pub struct EmptyExec {
         props: PlanProperties,
+        children: Vec<Arc<dyn ExecutionPlan>>,
     }
 
     impl EmptyExec {
@@ -305,6 +307,7 @@ mod tests {
                     EmissionType::Incremental,
                     Boundedness::Bounded,
                 ),
+                children: Vec::default(),
             }
         }
     }
@@ -333,14 +336,17 @@ mod tests {
         }
 
         fn children(&self) -> Vec<&Arc<dyn ExecutionPlan>> {
-            vec![]
+            self.children.iter().collect()
         }
 
         fn with_new_children(
             self: Arc<Self>,
-            _: Vec<Arc<dyn ExecutionPlan>>,
+            children: Vec<Arc<dyn ExecutionPlan>>,
         ) -> Result<Arc<dyn ExecutionPlan>> {
-            unimplemented!()
+            Ok(Arc::new(EmptyExec {
+                props: self.props.clone(),
+                children,
+            }))
         }
 
         fn execute(
@@ -358,7 +364,6 @@ mod tests {
 
     #[test]
     fn test_round_trip_ffi_execution_plan() -> Result<()> {
-        use arrow::datatypes::{DataType, Field, Schema};
         let schema =
             Arc::new(Schema::new(vec![Field::new("a", DataType::Float32, false)]));
         let ctx = SessionContext::new();
@@ -372,6 +377,49 @@ mod tests {
 
         assert!(original_name == foreign_plan.name());
 
+        let display = datafusion::physical_plan::display::DisplayableExecutionPlan::new(
+            &foreign_plan,
+        );
+
+        let buf = display.one_line().to_string();
+        assert_eq!(buf.trim(), "FFI_ExecutionPlan(number_of_children=0)");
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_ffi_execution_plan_children() -> Result<()> {
+        let schema =
+            Arc::new(Schema::new(vec![Field::new("a", DataType::Float32, false)]));
+        let ctx = SessionContext::new();
+
+        // Version 1: Adding child to the foreign plan
+        let child_plan = Arc::new(EmptyExec::new(Arc::clone(&schema)));
+        let child_local = FFI_ExecutionPlan::new(child_plan, ctx.task_ctx(), None);
+        let child_foreign = Arc::new(ForeignExecutionPlan::try_from(&child_local)?);
+
+        let parent_plan = Arc::new(EmptyExec::new(Arc::clone(&schema)));
+        let parent_local = FFI_ExecutionPlan::new(parent_plan, ctx.task_ctx(), None);
+        let parent_foreign = Arc::new(ForeignExecutionPlan::try_from(&parent_local)?);
+
+        assert_eq!(parent_foreign.children().len(), 0);
+        assert_eq!(child_foreign.children().len(), 0);
+
+        let parent_foreign = parent_foreign.with_new_children(vec![child_foreign])?;
+        assert_eq!(parent_foreign.children().len(), 1);
+
+        // Version 2: Adding child to the local plan
+        let child_plan = Arc::new(EmptyExec::new(Arc::clone(&schema)));
+        let child_local = FFI_ExecutionPlan::new(child_plan, ctx.task_ctx(), None);
+        let child_foreign = Arc::new(ForeignExecutionPlan::try_from(&child_local)?);
+
+        let parent_plan = Arc::new(EmptyExec::new(Arc::clone(&schema)));
+        let parent_plan = parent_plan.with_new_children(vec![child_foreign])?;
+        let parent_local = FFI_ExecutionPlan::new(parent_plan, ctx.task_ctx(), None);
+        let parent_foreign = Arc::new(ForeignExecutionPlan::try_from(&parent_local)?);
+
+        assert_eq!(parent_foreign.children().len(), 1);
+
         Ok(())
     }
 }
diff --git a/datafusion/ffi/src/insert_op.rs b/datafusion/ffi/src/insert_op.rs
index e44262377405..8e8693076cc0 100644
--- a/datafusion/ffi/src/insert_op.rs
+++ b/datafusion/ffi/src/insert_op.rs
@@ -47,3 +47,26 @@ impl From<InsertOp> for FFI_InsertOp {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use datafusion::logical_expr::dml::InsertOp;
+
+    use super::FFI_InsertOp;
+
+    fn test_round_trip_insert_op(insert_op: InsertOp) {
+        let ffi_insert_op: FFI_InsertOp = insert_op.into();
+        let round_trip: InsertOp = ffi_insert_op.into();
+
+        assert_eq!(insert_op, round_trip);
+    }
+
+    /// This test ensures we have not accidentally mapped the FFI
+    /// enums to the wrong internal enums values.
+    #[test]
+    fn test_all_round_trip_insert_ops() {
+        test_round_trip_insert_op(InsertOp::Append);
+        test_round_trip_insert_op(InsertOp::Overwrite);
+        test_round_trip_insert_op(InsertOp::Replace);
+    }
+}
diff --git a/datafusion/ffi/src/table_source.rs b/datafusion/ffi/src/table_source.rs
index a59836622ee6..418fdf16a564 100644
--- a/datafusion/ffi/src/table_source.rs
+++ b/datafusion/ffi/src/table_source.rs
@@ -85,3 +85,43 @@ impl From<TableType> for FFI_TableType {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use datafusion::error::Result;
+
+    fn round_trip_filter_pushdown(pushdown: TableProviderFilterPushDown) -> Result<()> {
+        let ffi_pushdown: FFI_TableProviderFilterPushDown = (&pushdown).into();
+        let round_trip: TableProviderFilterPushDown = (&ffi_pushdown).into();
+
+        assert_eq!(pushdown, round_trip);
+        Ok(())
+    }
+
+    #[test]
+    fn round_trip_all_filter_pushdowns() -> Result<()> {
+        round_trip_filter_pushdown(TableProviderFilterPushDown::Exact)?;
+        round_trip_filter_pushdown(TableProviderFilterPushDown::Inexact)?;
+        round_trip_filter_pushdown(TableProviderFilterPushDown::Unsupported)?;
+
+        Ok(())
+    }
+
+    fn round_trip_table_type(table_type: TableType) -> Result<()> {
+        let ffi_type: FFI_TableType = table_type.into();
+        let round_trip_type: TableType = ffi_type.into();
+
+        assert_eq!(table_type, round_trip_type);
+        Ok(())
+    }
+
+    #[test]
+    fn test_round_all_trip_table_type() -> Result<()> {
+        round_trip_table_type(TableType::Base)?;
+        round_trip_table_type(TableType::Temporary)?;
+        round_trip_table_type(TableType::View)?;
+
+        Ok(())
+    }
+}
diff --git a/datafusion/ffi/src/volatility.rs b/datafusion/ffi/src/volatility.rs
index 8b565b91b76d..0aaf68a174cf 100644
--- a/datafusion/ffi/src/volatility.rs
+++ b/datafusion/ffi/src/volatility.rs
@@ -46,3 +46,24 @@ impl From<&FFI_Volatility> for Volatility {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use datafusion::logical_expr::Volatility;
+
+    use super::FFI_Volatility;
+
+    fn test_round_trip_volatility(volatility: Volatility) {
+        let ffi_volatility: FFI_Volatility = volatility.into();
+        let round_trip: Volatility = (&ffi_volatility).into();
+
+        assert_eq!(volatility, round_trip);
+    }
+
+    #[test]
+    fn test_all_round_trip_volatility() {
+        test_round_trip_volatility(Volatility::Immutable);
+        test_round_trip_volatility(Volatility::Stable);
+        test_round_trip_volatility(Volatility::Volatile);
+    }
+}