Expose query interpolation util (#59)

Author: dprokop

datasource.go

@@ -174,7 +174,7 @@ func (ds *sqldatasource) handleQuery(ctx context.Context, req backend.DataQuery,
 	}
 
 	// Apply supported macros to the query
-	q.RawSQL, err = interpolate(ds.c, q)
+	q.RawSQL, err = Interpolate(ds.c, q)
 	if err != nil {
 		return getErrorFrameFromQuery(q), fmt.Errorf("%s: %w", "Could not apply macros", err)
 	}

macros.go

@@ -131,7 +131,8 @@ func getMacroRegex(name string) string {
 	return fmt.Sprintf("\\$__%s\\b(?:\\((.*?)\\))?", name)
 }
 
-func interpolate(driver Driver, query *Query) (string, error) {
+// Interpolate returns an interpolated query string given a backend.DataQuery
+func Interpolate(driver Driver, query *Query) (string, error) {
 	macros := driver.Macros()
 	for key, defaultMacro := range DefaultMacros {
 		if _, ok := macros[key]; !ok {

macros_test.go

@@ -73,7 +73,7 @@ func TestInterpolate(t *testing.T) {
 				Table:  tableName,
 				Column: tableColumn,
 			}
-			interpolatedQuery, err := interpolate(&driver, query)
+			interpolatedQuery, err := Interpolate(&driver, query)
 			require.Nil(t, err)
 			assert.Equal(t, tc.output, interpolatedQuery)
 		})