Add some basic tests

minisql/src/main.rs

@@ -5,6 +5,7 @@ use bimap::BiMap;
 // TODO: Note that every operation has a table name.
 //       Perhaps consider factoring the table name out
 //       and think of the operations as operating on a unique table.
+// TODO: `TableName` should be replaced by `TablePosition`
 enum Operation {
     Select(TableName, ColumnSelection, Option<Condition>),
     Insert(TableName, InsertionValues),
@@ -92,6 +93,7 @@ impl DbValue {
 type TableName = String;
 type TablePosition = usize;
 
+#[derive(Debug)]
 struct Table {
     schema: TableSchema,
     rows: Rows, // TODO: Consider wrapping this in a lock. Also consider if we need to have the
@@ -104,12 +106,14 @@ struct Table {
 //       Maybe we should have a separate index type for each type of value we're indexing over
 // TODO: I should have a set of UUID, not just a single UUID, e.g.
 //          a user table can have multiple different users with the same name.
+#[derive(Debug)]
 struct ColumnIndex {
     index: BTreeMap<IndexableDbValue, HashSet<UUID>>
 }
 
 // Note that it is nice to split metadata from the data because
 // then you can give the metadata to the parser without giving it the data.
+#[derive(Debug)]
 struct TableSchema {
     table_name: TableName, // used for descriptive errors
     primary_key: ColumnPosition,
@@ -150,12 +154,20 @@ fn select_columns(row: &Row, columns: &Vec<ColumnPosition>) -> Row {
 }
 
 // ==============Interpreter================
+#[derive(Debug)]
 struct State {
     table_name_position_mapping: BiMap<TableName, TablePosition>,
     tables: Vec<Table>,
 }
 
 impl State {
+    fn new() -> Self {
+        Self {
+            table_name_position_mapping: BiMap::new(),
+            tables: vec![],
+        }
+    }
+
     fn table_from_name<'b: 'a, 'a>(&'b self, table_name: &TableName) -> DbResult<&'a Table> {
         match self.table_name_position_mapping.get_by_left(table_name) {
             Some(table_position) => {
@@ -181,6 +193,54 @@ impl State {
         self.table_name_position_mapping.insert(table_name, new_table_position);
         self.tables.push(table);
     }
+
+    // TODO: Decide if we want for this to return a response (but then you have to deal with lifetimes,
+    //       because you'll be forced to put an iterator/slice into the Response data-structure.
+    //       Alternative is to pass a row-consumer to the functionas that knows how to communicate with
+    //       the client, but the details of communication are hidden behind an interface
+    //
+    //  writer: impl SqlConsumer
+    fn interpret(&mut self, operation: Operation) -> DbResult<Response>  {
+        // TODO: lock stuff
+        use Operation::*;
+
+        match operation {
+            Select(table_name, column_selection, maybe_condition) => {
+                let table: &Table = self.table_from_name(&table_name)?;
+                Ok(Response::Selected(table.select_where(column_selection, maybe_condition)?))
+            },
+            Insert(table_name, values) => {
+                let table: &mut Table = self.table_from_name_mut(&table_name)?;
+
+                let _ = table.insert(values)?;
+                Ok(Response::Inserted)
+            },
+            Delete(table_name, maybe_condition) => {
+                let table: &mut Table = self.table_from_name_mut(&table_name)?;
+
+                let rows_affected = table.delete_where(maybe_condition)?;
+                Ok(Response::Deleted(rows_affected))
+            },
+            CreateTable(table_name, table_schema) => {
+                let table = Table::new(table_schema);
+                self.attach_table(table_name, table);
+                Ok(Response::TableCreated)
+            },
+            CreateIndex(table_name, column_name) => {
+                // TODO: This is incomplete. It can happen that an index is created
+                //       after the table has some rows for a while.
+                //       In such a case the index needs to be built over all those existing rows.
+                let table: &mut Table = self.table_from_name_mut(&table_name)?;
+                let column_position: ColumnPosition = table.schema.column_position_from_column_name(&column_name)?;
+
+                let mut index: ColumnIndex = ColumnIndex::new();
+                let _ = index.update_from_table(&table, column_position)?;
+
+                table.attach_index(column_position, index); 
+                Ok(Response::IndexCreated)
+            },
+        }
+    }
 }
 
 // TODO: Give a better name to something that you can respond to with rows
@@ -188,51 +248,6 @@ trait SqlConsumer {
     // TODO: 
 }
 
-// TODO: Decide if we want for this to return a response (but then you have to deal with lifetimes,
-//       because you'll be forced to put an iterator/slice into the Response data-structure.
-//       Alternative is to pass a row-consumer to the functionas that knows how to communicate with
-//       the client, but the details of communication are hidden behind an interface
-fn interpret(table_name: TableName, operation: Operation, state: &mut State, consumer: impl SqlConsumer) -> DbResult<Response>  {
-    // TODO: lock stuff
-    use Operation::*;
-
-    match operation {
-        Select(table_name, column_selection, maybe_condition) => {
-            let table: &Table = state.table_from_name(&table_name)?;
-            Ok(Response::Selected(table.select_where(column_selection, maybe_condition)?))
-        },
-        Insert(table_name, values) => {
-            let table: &mut Table = state.table_from_name_mut(&table_name)?;
-
-            let _ = table.insert(values)?;
-            Ok(Response::Inserted)
-        },
-        Delete(table_name, maybe_condition) => {
-            let table: &mut Table = state.table_from_name_mut(&table_name)?;
-
-            let rows_affected = table.delete_where(maybe_condition)?;
-            Ok(Response::Deleted(rows_affected))
-        },
-        CreateTable(table_name, table_schema) => {
-            let table = Table::new(table_schema);
-            state.attach_table(table_name, table);
-            Ok(Response::TableCreated)
-        },
-        CreateIndex(table_name, column_name) => {
-            // TODO: This is incomplete. It can happen that an index is created
-            //       after the table has some rows for a while.
-            //       In such a case the index needs to be built over all those existing rows.
-            let table: &mut Table = state.table_from_name_mut(&table_name)?;
-            let column_position: ColumnPosition = table.schema.column_position_from_column_name(&column_name)?;
-
-            let mut index: ColumnIndex = ColumnIndex::new();
-            let _ = index.update_from_table(&table, column_position)?;
-
-            table.attach_index(column_position, index); 
-            Ok(Response::IndexCreated)
-        },
-    }
-}
 
 impl TableSchema {
     fn get_column(&self, column_name: &ColumnName) -> DbResult<(DbType, ColumnPosition)> {
@@ -304,7 +319,7 @@ impl TableSchema {
             return Err(Error::MismatchBetweenInsertValuesAndColumns(self.table_name.clone(), insertion_values))
         }
 
-        let mut row: Vec<DbValue> = Vec::with_capacity(number_of_columns);
+        let mut row: Row = Vec::with_capacity(number_of_columns);
 
         let mut values: HashMap<ColumnName, DbValue> = HashMap::new();
         for (column_name, db_value) in &insertion_values {
@@ -564,6 +579,7 @@ impl ColumnIndex {
     }
 }
 
+#[derive(Debug)]
 enum Response {
     Selected(Vec<Row>),
     Inserted,
@@ -574,7 +590,7 @@ enum Response {
 
 type DbResult<A> = Result<A, Error>;
 
-// #[derive(Debug)]
+#[derive(Debug)]
 enum Error {
     TableDoesNotExist(TableName),
     ColumnDoesNotExist(TableName, ColumnName),
@@ -590,3 +606,188 @@ enum Error {
 fn main() {
     println!("Hello, world!");
 }
+
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn users_schema() -> TableSchema {
+        let id: ColumnPosition = 0;
+        let name: ColumnPosition = 1;
+        let age: ColumnPosition = 2;
+
+        TableSchema {
+            table_name: "users".to_string(),
+            primary_key: 0,
+            column_name_position_mapping: {
+                let mut mapping: BiMap<ColumnName, ColumnPosition> = BiMap::new();
+                mapping.insert("id".to_string(), id);
+                mapping.insert("name".to_string(), name);
+                mapping.insert("age".to_string(), age);
+                mapping
+            },
+            types: vec![DbType::UUID, DbType::String, DbType::Int],
+        }
+    }
+
+    #[test]
+    fn test_table_creation() {
+        let mut state = State::new();
+        let users_schema = users_schema();
+        let users = users_schema.table_name.clone();
+
+        state.interpret(Operation::CreateTable(users.clone(), users_schema)).unwrap();
+
+        assert!(state.tables.len() == 1);
+        let table = &state.tables[0];
+        assert!(table.rows.len() == 0);
+
+        assert!(table.schema.table_name == users);
+    }
+
+    #[test]
+    fn test_select_empty() {
+        let mut state = State::new();
+        let users_schema = users_schema();
+        let users = users_schema.table_name.clone();
+
+        state.interpret(Operation::CreateTable(users.clone(), users_schema)).unwrap();
+        let response: Response = state.interpret(Operation::Select(users.clone(), ColumnSelection::All, None)).unwrap();
+        assert!(matches!(response, Response::Selected(_)));
+        let Response::Selected(rows) = response else { todo!() };
+        assert!(rows.len() == 0);
+
+    }
+
+    #[test]
+    fn test_select_nonexistant_table() {
+        let mut state = State::new();
+
+        let response: DbResult<Response> = state.interpret(Operation::Select("table_that_doesnt_exist".to_string(), ColumnSelection::All, None));
+        assert!(matches!(response, Err(Error::TableDoesNotExist(_))));
+    }
+
+    #[test]
+    fn test_insert_select_basic1() {
+        use DbValue::*;
+        use IndexableDbValue::*;
+
+        let mut state = State::new();
+        let users_schema = users_schema();
+        let users = users_schema.table_name.clone();
+
+        state.interpret(Operation::CreateTable(users.clone(), users_schema)).unwrap();
+
+        let (id, name, age) = (
+            Indexable(UUID(0)),
+            Indexable(String("Plato".to_string())),
+            Indexable(Int(64))
+        );
+        state.interpret(Operation::Insert(users.clone(), vec![
+            ("id".to_string(), id.clone()),
+            ("name".to_string(), name.clone()),
+            ("age".to_string(), age.clone()),
+        ])).unwrap();
+
+        let response: Response = state.interpret(Operation::Select(users.clone(), ColumnSelection::All, None)).unwrap();
+
+        assert!(matches!(response, Response::Selected(_)));
+        let Response::Selected(rows) = response else { todo!() };
+        assert!(rows.len() == 1);
+        let row = &rows[0];
+
+        assert!(row.len() == 3);
+        assert!(row[0] == id);
+        assert!(row[1] == name);
+        assert!(row[2] == age);
+    }
+
+    #[test]
+    fn test_insert_select_basic2() {
+        use DbValue::*;
+        use IndexableDbValue::*;
+        use Operation::*;
+        use ColumnSelection::*;
+        use Condition::*;
+
+        let mut state = State::new();
+        let users_schema = users_schema();
+        let users = users_schema.table_name.clone();
+
+        state.interpret(CreateTable(users.clone(), users_schema)).unwrap();
+
+        let response0: Response = state.interpret(Select(users.clone(), ColumnSelection::All, None)).unwrap();
+        assert!(matches!(response0, Response::Selected(_)));
+        let Response::Selected(rows0) = response0 else { todo!() };
+        assert!(rows0.len() == 0);
+
+        let (id0, name0, age0) = (
+            Indexable(UUID(0)),
+            Indexable(String("Plato".to_string())),
+            Indexable(Int(64))
+        );
+        state.interpret(Insert(users.clone(), vec![
+            ("id".to_string(), id0.clone()),
+            ("name".to_string(), name0.clone()),
+            ("age".to_string(), age0.clone()),
+        ])).unwrap();
+
+        let (id1, name1, age1) = (
+            Indexable(UUID(1)),
+            Indexable(String("Aristotle".to_string())),
+            Indexable(Int(20))
+        );
+        state.interpret(Insert(users.clone(), vec![
+            ("id".to_string(), id1.clone()),
+            ("name".to_string(), name1.clone()),
+            ("age".to_string(), age1.clone()),
+        ])).unwrap();
+
+        {
+            let response: Response = state.interpret(Select(users.clone(), All, None)).unwrap();
+
+            assert!(matches!(response, Response::Selected(_)));
+            let Response::Selected(rows) = response else { todo!() };
+            assert!(rows.len() == 2);
+            let row0 = &rows[0];
+            let row1 = &rows[1];
+
+            assert!(row0.len() == 3);
+            assert!(row0[0] == id0);
+            assert!(row0[1] == name0);
+            assert!(row0[2] == age0);
+
+            assert!(row1.len() == 3);
+            assert!(row1[0] == id1);
+            assert!(row1[1] == name1);
+            assert!(row1[2] == age1);
+        }
+
+        {
+            let response: Response = state.interpret(Select(users.clone(), All, Some(Eq("id".to_string(), id0.clone())))).unwrap();
+            assert!(matches!(response, Response::Selected(_)));
+            let Response::Selected(rows) = response else { todo!() };
+            assert!(rows.len() == 1);
+            let row0 = &rows[0];
+
+            assert!(row0.len() == 3);
+            assert!(row0[0] == id0);
+            assert!(row0[1] == name0);
+            assert!(row0[2] == age0);
+        }
+
+        {
+            let response: Response = state.interpret(Select(users.clone(), Columns(vec!["name".to_string(), "id".to_string()]), Some(Eq("id".to_string(), id0.clone())))).unwrap();
+            assert!(matches!(response, Response::Selected(_)));
+            let Response::Selected(rows) = response else { todo!() };
+            assert!(rows.len() == 1);
+            let row0 = &rows[0];
+
+            assert!(row0.len() == 2);
+            assert!(row0[0] == name0);
+            assert!(row0[1] == id0);
+        }
+    }
+}