databasename..sp_helpprotect 'storedProcedureName', 'username'

databasename..sp_canexecute 'storedProcedureName', 'username'

EXECUTE AS USER = 'username';
SELECT * FROM fn_my_permissions('[storedProcedureSchema].[storedProcedureName]', 'OBJECT')
    where permission_name = 'EXECUTE'
    ORDER BY subentity_name, permission_name ;
REVERT;

CREATE PROCEDURE [dbo].[sp_canexecute]
@procedure_name varchar(255),
@username varchar(255),
@has_execute_permissions bit OUTPUT
AS

IF EXISTS (
    	/* Explicit permission */
    	SELECT 1
    	FROM sys.database_permissions p
    	INNER JOIN sys.all_objects o ON p.major_id = o.[object_id] AND o.[name] = @procedure_name
    	INNER JOIN sys.database_principals dp ON p.grantee_principal_id = dp.principal_id AND dp.[name] = @username
    )
    OR EXISTS (
    	/* Role-based permission */
    	SELECT 1
    	FROM sys.database_permissions p
    	INNER JOIN sys.all_objects o ON p.major_id = o.[object_id]
    	INNER JOIN sys.database_principals dp ON p.grantee_principal_id = dp.principal_id AND o.[name] = @procedure_name
    	INNER JOIN sys.database_role_members drm ON dp.principal_id = drm.role_principal_id
    	INNER JOIN sys.database_principals dp2 ON drm.member_principal_id = dp2.principal_id AND dp2.[name] = @username
    )
BEGIN
    SET @has_execute_permissions = 1
END
ELSE
BEGIN
    SET @has_execute_permissions = 0
END
GO