Add SQL ping function (#11)

* Add SQL ping function

* Add sql ping tests

* Update README for ping

Author: BrandonRomano

README.md

@@ -132,6 +132,28 @@ if [[ $? -ne 0 ]]; then
 fi
 ```
 
+> Note: You can't run this function in a subshell, as it is responsible for sourcing in specific driver files.
+
+### Testing Connections
+
+After you open a connection, you'll likely want to verify we can actually start executing queries against it.
+
+You can test a connection by calling `Sql__ping`.
+
+```sh
+# Test connection
+local ping_output
+ping_output=$(Sql__ping)
+if [[ $? -ne 0 ]]; then
+    Sql__close
+    echo "Error connecting to database:"
+    echo "$ping_output"
+    return 1
+fi
+```
+
+> The reason why this doesn't just automatically happen in `Sql__open` is because you can't run `Sql__open` in a subshell (as it sources other files), and this function has output that we want to capture.
+
 ### Closing Connections
 
 After you are done running all of your queries against the database, you will now have to close your database.

lib/drivers/interface.sh

@@ -15,20 +15,35 @@
 # @param $1: The statement to be executed
 #################################################
 Sql__execute() {
-    Logger__error "No sql driver selected, must call 'Sql__open' before calling 'Sql__execute'"
+    echo "No sql driver selected, must call 'Sql__open' before calling 'Sql__execute'"
+    return 1
 }
 
+
+#################################################
+# Pings the database to verify if we have a
+# valid connection.
+
+# @returns: 0 if we have a valid connection,
+#   1 otherwise
+#################################################
+Sql__ping() {
+    echo "No sql driver selected, must call 'Sql__open' before calling 'Sql__ping'"
+    return 1
+}
+
+
 #################################################
 # Checks if a specific table exists in the
 # database.
 #
 # @param $1: The name of the table to check if
 #   if it exists.
-# @returns: 0 if a table exists, 1 if no table
-#   exists
+# @returns: 0 if a table exists, 1 otherwise
 #################################################
 Sql__table_exists() {
-    Logger__error "No sql driver selected, must call 'Sql__open' before calling 'Sql__table_exists'"
+    echo "No sql driver selected, must call 'Sql__open' before calling 'Sql__table_exists'"
+    return 1
 }
 
 #################################################

lib/drivers/mysql.sh

@@ -20,6 +20,24 @@ Sql__execute() {
         2>&1
 }
 
+#################################################
+# Pings the database to verify if we have a
+# valid connection.
+
+# @returns: 0 if we have a valid connection,
+#   1 otherwise
+#################################################
+Sql__ping() {
+    local out
+    out=$(Sql__execute "SELECT 1;")
+    if [[ $? -eq 0 ]]; then
+        return 0
+    else
+        echo "$out"
+        return 1
+    fi
+}
+
 #################################################
 # Checks if a specific table exists in the
 # database.

lib/drivers/postgres.sh

@@ -22,6 +22,24 @@ Sql__execute() {
     return $result
 }
 
+#################################################
+# Pings the database to verify if we have a
+# valid connection.
+
+# @returns: 0 if we have a valid connection,
+#   1 otherwise
+#################################################
+Sql__ping() {
+    local out
+    out=$(Sql__execute "SELECT 1;")
+    if [[ $? -eq 0 ]]; then
+        return 0
+    else
+        echo "$out"
+        return 1
+    fi
+}
+
 #################################################
 # Checks if a specific table exists in the
 # database.

lib/sql.sh

@@ -12,11 +12,12 @@ Sql__DRIVER_POSTGRES='postgres'
 # all other setup operations
 #
 # @param $1: The driver to setup
+# @returns: 1 if the driver is invalid,
+#   0 otherwise
 #################################################
 Sql__open() {
     local driver="$1"
     if [[ "$driver" = "" ]]; then
-        echo "Sql__open must be passed a database driver name"
         return 1
     fi
 
@@ -26,7 +27,6 @@ Sql__open() {
     elif [[ "$driver" = "$Sql__DRIVER_POSTGRES" ]]; then
         . "$Sql__PACKAGE_LOCATION/lib/drivers/postgres.sh"
     else
-        echo "Invalid sql driver name '$driver'"
         return 1
     fi
 

test.sh

@@ -3,14 +3,23 @@
 #################################################
 # Tests the failure cases of Sql__open
 #################################################
-Sql__test_open_failure(){
+Sql__test_open_failure() {
     # Trying to run 'Sql__open' with an invalid driver
     open_hello=$(Sql__open "hello")
     if [[ $? -eq 0 ]]; then
         echo "'Sql__open' should return an error when trying to open driver 'hello'"
         return 1;
     fi
 
+    # Test connection
+    local ping_output
+    ping_output=$(Sql__ping)
+    if [[ $? -eq 0 ]]; then
+        Sql__close
+        echo "Should not be connected to a database on an open failure"
+        return 1
+    fi
+
     # Trying to run 'Sql__open' with no driver
     open_no_driver=$(Sql__open)
     if [[ $? -eq 0 ]]; then
@@ -22,104 +31,90 @@ Sql__test_open_failure(){
 #################################################
 # Tests the success case of Sql__open for PostgreSQL
 #################################################
-Sql__test_postgres_open(){
-    # Open DB
-    Sql__open "$Sql__DRIVER_POSTGRES"
-    if [[ $? -ne 0 ]]; then
-        echo "'Sql__open' returned an error"
-        return 1
-    fi
-
-    # Close DB
-    Sql__close
-    if [[ $? -ne 0 ]]; then
-        echo "'Sql__close' returned an error"
-        return 1
-    fi
+Sql__test_postgres_open() {
+    Sql_test_generic_open "$Sql__DRIVER_POSTGRES"
 }
 
 #################################################
 # Tests the success case of Sql__open for MySQL
-#
-# This tests differs from PostgreSQL because
-# this actually tests an implementation detail
-# that users don't particularly need to worry
-# about, but is important to test from the
-# testing end.  The two interfaces for both
-# drivers are still exactly the same.
-#################################################
-Sql__test_mysql_open(){
-    # Open DB
-    Sql__open "$Sql__DRIVER_MYSQL"
-    if [[ $? -ne 0 ]]; then
-        echo "'Sql__open' returned an error"
-        return 1
-    fi
-
-    # Verify MySQL config file was created
-    if [[ ! -f "$SQL_MYSQL_CONFIG_FILE" ]]; then
-        echo "MySQL config file was not created"
-        echo "Make sure you have permissions to write to $SQL_MYSQL_CONFIG_FILE"
-        return 1
-    fi
-
-    # Close DB
-    Sql__close
-    if [[ $? -ne 0 ]]; then
-        echo "'Sql__close' returned an error"
-        return 1
-    fi
-
-    # Verify MySQL config file was deleted
-    if [[ -f "$SQL_MYSQL_CONFIG_FILE" ]]; then
-        echo "MySQL config file was not deleted"
-        echo "Make sure you have permissions to delete $SQL_MYSQL_CONFIG_FILE"
-        return 1
-    fi
+#################################################
+Sql__test_mysql_open() {
+    Sql_test_generic_open "$Sql__DRIVER_MYSQL"
 }
 
 #################################################
 # Tests a successful PostgreSQL query
 #################################################
-Sql__test_postgres_query(){
-    Sql__generic_test_query "$Sql__DRIVER_POSTGRES"
+Sql__test_postgres_query() {
+    Sql_test_generic_query "$Sql__DRIVER_POSTGRES"
 }
 
 #################################################
 # Tests a successful MySQL query
 #################################################
-Sql__test_mysql_query(){
-    Sql__generic_test_query "$Sql__DRIVER_MYSQL"
+Sql__test_mysql_query() {
+    Sql_test_generic_query "$Sql__DRIVER_MYSQL"
 }
 
 #################################################
 # Tests the a failed PostgreSQL query
 #################################################
-Sql__test_postgres_query_failure(){
-    Sql__generic_test_query_failure "$Sql__DRIVER_POSTGRES"
+Sql__test_postgres_query_failure() {
+    Sql_test_generic_query_failure "$Sql__DRIVER_POSTGRES"
 }
 
 #################################################
 # Tests the a failed MySQL query
 #################################################
-Sql__test_mysql_query_failure(){
-    Sql__generic_test_query_failure "$Sql__DRIVER_MYSQL"
+Sql__test_mysql_query_failure() {
+    Sql_test_generic_query_failure "$Sql__DRIVER_MYSQL"
 }
 
 #################################################
 # Test the successful and unsuccessful case for
 # the Sql__table_exists function for PostgreSQL
 #################################################
-Sql__test_postgres_table_exists(){
-    Sql__generic_test_table_exists "$Sql__DRIVER_POSTGRES"
+Sql__test_postgres_table_exists() {
+    Sql_test_generic_table_exists "$Sql__DRIVER_POSTGRES"
 }
 
 #################################################
 # Test the successful and unsuccessful case for
 # the Sql__table_exists function for MySQL
 #################################################
-Sql__test_mysql_table_exists(){
-    Sql__generic_test_table_exists "$Sql__DRIVER_MYSQL"
+Sql__test_mysql_table_exists() {
+    Sql_test_generic_table_exists "$Sql__DRIVER_MYSQL"
+}
+
+#################################################
+# Tests the success case of Sql__open for a driver
+#
+# @param $1: The driver to test
+#################################################
+Sql_test_generic_open() {
+    # Open DB
+    Sql__open "$1"
+    if [[ $? -ne 0 ]]; then
+        echo "'Sql__open' returned an error"
+        return 1
+    fi
+
+    # Test connection
+    local ping_output
+    ping_output=$(Sql__ping)
+    if [[ $? -ne 0 ]]; then
+        Sql__close
+        echo -e "Error connecting to database:"
+        echo "$ping_output"
+        return 1
+    fi
+
+    # Close DB
+    Sql__close
+    if [[ $? -ne 0 ]]; then
+        echo "'Sql__close' returned an error"
+        return 1
+    fi
 }
 
 #################################################
@@ -128,7 +123,7 @@ Sql__test_mysql_table_exists(){
 #
 # @param $1: The driver to test
 #################################################
-Sql__generic_test_query(){
+Sql_test_generic_query() {
     # Open DB
     Sql__open "$1"
 
@@ -174,7 +169,7 @@ Sql__generic_test_query(){
 #
 # @param $1: The driver to test
 #################################################
-Sql__generic_test_query_failure() {
+Sql_test_generic_query_failure() {
     # Open DB
     Sql__open "$1"
     if [[ $? -ne 0 ]]; then
@@ -203,7 +198,7 @@ Sql__generic_test_query_failure() {
 #
 # @param $1: The driver to test
 #################################################
-Sql__generic_test_table_exists() {
+Sql_test_generic_table_exists() {
     # Open DB
     Sql__open "$1"
     if [[ $? -ne 0 ]]; then