Liming's Blog

Behaivour-driven development using plain Chinese story

2008-10-18T20:17:00.000-07:00

This blog post is talking about how to use rspec and cucumber in Ruby to make behavior driven development with plain story in Chinese language.

It seems behaviour-driven development is getting more and more popular in recent days. If you are still not sure what BDD is, take a look at following links:

1] Introducing BDD by Dan North
2] Beyond Test Driven Development: Behaviour Driven Development, Google Talk, by Dave Astels
3] Behaviour Driven Development with RSpec, RubyConf 2007, by David Chelimsky, Dave Astels

The most interesting feature of BDD is using stories of plain text as the test cases. Here the story text itself is not only the description of the application's functionality, but also the executable acceptance criterion of application's behavior. Let's have a look at the story example of a calculator addition feature:

Feature: Addition
 In order to avoid silly mistakes
 As a math idiot
 I want to be told the sum of two numbers

Scenario: Add two numbers
 Given I have entered 50 into the calculator
 And I have entered 70 into the calculator
 When I press add
 Then the result should be 120 on the screen
 And the result class should be Fixnum

Both developers and customers can benefit from above story since it is in plain text and easily understood. The further question you might ask is that if it is possible to use spoken languages other than English to write our BDD stories? The answer is "definitely yes!". Thanks to the cucumber -- the new RSpec's Story Runner. Multiple spoken languages support is a built-in feature of cucumber.

The first step is to install cucumber, make sure you have install rpsec. You can install cucumber from gem:

gem install cucumber

or building gem yourself:

git clone git://github.com/aslakhellesoy/cucumber.git
cd cucumber
rake install_gem

The keyword translation for Chinese language in cucumber is defined as following:

"zh-CN":
   feature: 功能
   scenario: 场景
   given_scenario: 引用场景
   given: 假如
   when: 当
   then: 那么
   and: 而且
   but: 但是

OK, let's write our story in Chinese:

功能:加法
 为了避免一些愚蠢的错误
 作为一个数学白痴
 我希望有人告诉我数字相加的结果

场景: 两个数相加
 假如我已经在计算器里输入6
 而且我已经在计算器里输入7
 当我按相加按钮
 那么我应该在屏幕上看到的结果是13

场景: 三个数相加
 假如我已经在计算器里输入6
 而且我已经在计算器里输入7
 而且我已经在计算器里输入1
 当我按相加按钮
 那么我应该在屏幕上看到的结果是14

Save the plain text in Chinese to a file, here we give it name "addition.feature". Now we can run this feature in command line:

> cucumber --language zh-CN addition.feature

You should see following output:

功能:加法  # addition.feature
 为了避免一些愚蠢的错误
 作为一个数学白痴
 我希望有人告诉我数字相加的结果

场景: 两个数相加                             # addition.feature:6
 假如 我已经在计算器里输入6            # addition.feature:7
 而且 我已经在计算器里输入7            # addition.feature:8
 当 我按相加按钮                            # addition.feature:9
 那么 我应该在屏幕上看到的结果是13  # addition.feature:10

场景: 三个数相加                             # addition.feature:12
 假如 我已经在计算器里输入6            # addition.feature:13
 而且 我已经在计算器里输入7            # addition.feature:14
 而且 我已经在计算器里输入1            # addition.feature:15
 当 我按相加按钮                            # addition.feature:16
 那么 我应该在屏幕上看到的结果是14  # addition.feature:17

9 steps pending

You can use these snippets to implement pending steps:

假如 /^我已经在计算器里输入6$/ do
end

假如 /^我已经在计算器里输入7$/ do
end

当 /^我按相加按钮$/ do
end

那么 /^我应该在屏幕上看到的结果是13$/ do
end

假如 /^我已经在计算器里输入1$/ do
end

那么 /^我应该在屏幕上看到的结果是14$/ do
end

See pending step notification? Yes, that is because we haven't defined the steps for this feature. Before we define the steps, we might first consider writing our calculator code. Following is a simple implementation. Here we add a silly bug(The initial sum is not 0 but 1) to let cucumber report it.


class Calculator
  def push(n)
    @args ||= []
    @args << n
  end

 def add
    @args.inject(1){|n,sum| sum+=n}
 end
end

Save the code to a local file within the same directory of your feature file. Now let's define the step matcher for addition feature with Calculator class defined above.

require 'spec'
require 'calculator'

Before do
 @calc = Calculator.new
end

After do
end

Given "我已经在计算器里输入$n" do |n|
 @calc.push n.to_i
end

When /我按(.*)按钮/ do |op|
 if op == '相加'
   @result = @calc.send "add"
 end
end

Then /我应该在屏幕上看到的结果是(.*)/ do |result|
 @result.should == result.to_f
end

Now run the feature again, you should see:

功能:加法  # addition.feature
 为了避免一些愚蠢的错误
 作为一个数学白痴
 我希望有人告诉我数字相加的结果

 场景: 两个数相加                             # addition.feature:6
   假如 我已经在计算器里输入6            # calculator_steps.rb:11
   而且 我已经在计算器里输入7            # calculator_steps.rb:11
   当 我按相加按钮                            # calculator_steps.rb:15
   那么 我应该在屏幕上看到的结果是13  # calculator_steps.rb:21
expected: 13.0,
   got: 14 (using ==) (Spec::Expectations::ExpectationNotMetError)
./calculator_steps.rb:22:in `那么 /461021457224505745453450456117457125447012473413451060473204477323463634463057(.*)/'
addition.feature:10:in `那么 我应该在屏幕上看到的结果是13'

 场景: 三个数相加                             # addition.feature:12
   假如 我已经在计算器里输入6            # calculator_steps.rb:11
   而且 我已经在计算器里输入7            # calculator_steps.rb:11
   而且 我已经在计算器里输入1            # calculator_steps.rb:11
   当 我按相加按钮                            # calculator_steps.rb:15
   那么 我应该在屏幕上看到的结果是14  # calculator_steps.rb:21
expected: 14.0,
  got: 15 (using ==) (Spec::Expectations::ExpectationNotMetError)
./calculator_steps.rb:22:in `那么 /461021457224505745453450456117457125447012473413451060473204477323463634463057(.*)/'
addition.feature:17:in `那么 我应该在屏幕上看到的结果是14'

Lets change the calculator class to fix the bug:

class Calculator
   def push(n)
     @args ||= []
     @args << n
   end

  def add
     @args.inject(0){|n,sum| sum+=n}
  end
end

And run cucumber again, you should see:

功能:加法  # addition.feature
 为了避免一些愚蠢的错误
 作为一个数学白痴
 我希望有人告诉我数字相加的结果

场景: 两个数相加                             # addition.feature:6
 假如 我已经在计算器里输入6            # calculator_steps.rb:11
 而且 我已经在计算器里输入7            # calculator_steps.rb:11
 当 我按相加按钮                            # calculator_steps.rb:15
 那么 我应该在屏幕上看到的结果是13  # calculator_steps.rb:21

场景: 三个数相加                             # addition.feature:12
 假如 我已经在计算器里输入6            # calculator_steps.rb:11
 而且 我已经在计算器里输入7            # calculator_steps.rb:11
 而且 我已经在计算器里输入1            # calculator_steps.rb:11
 当 我按相加按钮                            # calculator_steps.rb:15
 那么 我应该在屏幕上看到的结果是14  # calculator_steps.rb:21

9 steps passed

Congratulations! All steps passed!

You can find the code of this example at /examples/chinese_simplified_calculator of cucumber git repository(git://github.com/aslakhellesoy/cucumber.git).

Use http proxy for git client

2008-08-26T23:17:00.000-07:00

I am using a network behind a http proxy. As more and more Rails projects migrate to Git, for accessing those external Git repositories, I'd like to have a method to configure Git client to go through the http proxy. By searching the web, I found several solutions. After some trying, I found the easiest approach is to use transconnect.

I am using Ubuntu and find that there is no package support for transconnect. So I have to install it manually from the source code, fortunately, it is fairly easy to setup transconnect. Following is the steps:

1) Download transconnect source code from its website

2) Uncompress the .tar.gz package, to install it, simply type:

make
make install

The above is the standard installation, for others, please refer to INSTALL located within the uncompressed directory.

3) A new directory '.tconn' will be created under your HOME directory by the installer and a config file 'tconn.conf' will be copied to that directory. Open 'tconn.conf', you will find two options named 'proxyserv' and 'proxyport'. Replace the default value with the proxy you are in use.

And that's all for setting!

4) It is easy to start transconnect by exporting an environment variable:

LD_PRELOAD=$HOME/.tconn/tconn.so
export LD_PRELOAD

After that, try your git client, it should work on current terminal by going through the proxy you have set.

5) It is also easy to stop transconnect. In the terminal you have exported LD_RELOAD, simply unset it.

unset LD_PRELOAD

Yes, that's all, enjoy!

Ruby-OCI8 1.0.2 gem is available

2008-07-03T00:20:00.001-07:00

As Kubo announced in Ruby mailing list, with the release of version 1.0.2, the gem of Ruby-OCI8 is available. Now you can easily install ruby-oci8 by simple commd "gem install ruby-oci8".

Though the installation of Ruby-OCI8 has been eased a lot with gem, you still have to pay attention to:

1) The same as installation from source code, Oracle client is still required to be installed before the gem installation. Check help page "Oracle Full Client" and "Oracle Instant Client" on ruby-oci8 website for details, please be specially careful to the setting of environment variable "LD_LIBRARY_PATH".

2) If you don't tell the ruby to load RubyGems every time it starts up by setting the environment variable "RUBYOPT" to "rubygems", you should add "require 'rubygems'" before "require 'oci8'", or you will get error "no such file to load -- oci8".

Now the Ruby-OCI8 gem is only available for version 1.0.2, no support for 2.0 yet.

Ruby-OCI8 2.0 New Feature: Complete Schema Object Metadata Describe Support

2008-05-09T07:49:00.000-07:00

1, Introduction

This feature enables you to perform an explicit describe of the following schema objects and their subschema objects via Ruby-OCI8:

tables and views
synonyms
procedures
functions
packages
sequences
collections
types
schemas
databases

Information about other schema elements (procedure/function arguments, columns, type attributes, and type methods) is available through a describe of one of the above schema objects or an explicit describe of the subschema object.

2, Ruby-OCI8 2.0 Installation

svn co http://ruby-oci8.rubyforge.org/svn/trunk/ruby-oci8

And then follow the Ruby-OCI8 install instruction.

3,Metadata Describe API

[General Purpose]
This method can be used to describe any schema object.
OCI8#describe_any(object_name)

[table or view]
OCI8#describe_table(table_name, table_only = false)
Return:
OCI8::Metadata::Table

[view]
OCI8#describe_view(view_name)
Return:
OCI8::Metadata::View

[procedure]
OCI8#describe_procedure(procedure_name)
Return:
OCI8::Metadata::Procedure

[function]
OCI8#describe_function(function_name)
Return:
OCI8::Metadata::Function

[package]
OCI8#describe_package(package_name)
Return:
OCI8::Metadata::Package

[type]
OCI8#describe_type(type_name)
Return:
OCI8::Metadata::Type

[synonym]
OCI8#describe_synonym(synonym_name, check_public_also = false)
Return:
OCI8::Metadata::Synonym

[sequence]
OCI8#describe_sequence(sequence_name)
Return:
OCI8::Metadata::Sequence

[schema]
OCI8#describe_schema(schema_name)
Return:
OCI8::Metadata::Schema

[database]
OCI8#describe_database(database_name)
Return:
OCI8::Metadata::Database

4, Examples

4.1 Describe Table

Table definition:

CREATE TABLE employees_demo(
  employee_id    NUMBER(6),
  first_name     VARCHAR2(20),
  last_name      VARCHAR2(25),
  email          VARCHAR2(25)
)

Describe via Ruby-OCI8

require 'oci8'
conn = OCI8.new('ruby','oci8','localhost')
emp_tab = conn.describe_table('employees_demo')
puts "Table Name: #{emp_tab.obj_name}"
emp_tab.columns.each do |col|
  puts "  Column #{col.name}, type: #{col.data_type}, size: #{col.data_size}"
end
conn.logoff

Output:

Table Name: EMPLOYEES_DEMO
  Column EMPLOYEE_ID, type: number, size: 22
  Column FIRST_NAME, type: varchar2, size: 20
  Column LAST_NAME, type: varchar2, size: 25
  Column EMAIL, type: varchar2, size: 25

4.2 Describe Procedure

Procedure definition:

CREATE OR REPLACE PROCEDURE get_name(emp_id IN NUMBER, emp_name OUT VARCHAR2) AS
  emp_fn VARCHAR2(20);
  emp_ln VARCHAR2(25);
BEGIN
SELECT first_name, last_name INTO emp_fn, emp_ln
  FROM employees_demo WHERE employee_id = emp_id;
emp_name := emp_fn || ' ' ||  emp_ln;
END;

Describe via Ruby-OCI8

require 'oci8'
conn = OCI8.new('ruby','oci8','localhost')
get_name_proc = conn.describe_procedure('get_name')
puts "Procedure Name: #{get_name_proc.obj_name}"
args = get_name_proc.arguments
args.each { |arg|
  puts "  Argument #{arg.name}, type: #{arg.data_type}, in/out: #{arg.iomode.to_s}"
}
conn.logoff

Output:

Procedure Name: GET_NAME
  Argument EMP_ID, type: number, in/out: in
  Argument EMP_NAME, type: varchar2, in/out: out

4.3 Describe Function

Function definition:

CREATE OR REPLACE FUNCTION get_email(emp_id NUMBER)
RETURN VARCHAR2 AS
  emp_email VARCHAR2(25);
BEGIN
  SELECT email INTO emp_email FROM employees_demo
    WHERE employee_id = emp_id;
  RETURN(emp_email);
END;

Describe via Ruby-OCI8

get_email_func = conn.describe_function('get_email')
puts "Function Name: #{get_email_func.obj_name}"
args = get_email_func.arguments
args.each_index { |i|
if i == 0
  puts "  Return Type: #{args[i].data_type}"
else
  puts "  Argument #{i}: #{args[i].name}, Type: #{args[i].data_type}"
end                     
}

Output:

Function Name: GET_EMAIL
  Return Type: varchar2
  Argument 1: EMP_ID, Type: number

4.4 Describe Package

Package Definition

CREATE OR REPLACE PACKAGE emp_pkg AS
  FUNCTION get_email(emp_id NUMBER) RETURN VARCHAR2;
  PROCEDURE get_name(emp_id IN NUMBER, emp_name OUT VARCHAR2);
END emp_pkg;

CREATE OR REPLACE PACKAGE BODY emp_pkg AS
  FUNCTION get_email(emp_id NUMBER)
  RETURN VARCHAR2 AS
    emp_email VARCHAR2(25);
  BEGIN
    SELECT email INTO emp_email FROM employees_demo
      WHERE employee_id = emp_id;
    RETURN(emp_email);
  END;

  PROCEDURE get_name(emp_id IN NUMBER, emp_name OUT VARCHAR2) AS
    emp_fn VARCHAR2(20);
    emp_ln VARCHAR2(25);
  BEGIN
    SELECT first_name, last_name INTO emp_fn, emp_ln
      FROM employees_demo WHERE employee_id = emp_id;
    emp_name := emp_fn || ' ' ||  emp_ln;
  END;
END emp_pkg;

Describe via Ruby-OCI8

require 'oci8'
conn = OCI8.new('ruby','oci8','localhost')
emp_pkg = conn.describe_package('emp_pkg')
puts "Package Name: #{emp_pkg.obj_name}"
sub_progs = emp_pkg.subprograms
sub_progs.each { |subp|
  if subp.is_a? OCI8::Metadata::Function
    puts "Subprogram:  Function #{subp.name}"
    args = subp.arguments
    args.each_index { |i|
      if i == 0
        puts "  Return Type: #{args[i].data_type}"
      else
        puts "  Argument #{i}: #{args[i].name}, Type: #{args[i].data_type}"                       
      end
    }
  elsif subp.is_a? OCI8::Metadata::Procedure
    puts "Subprogram:  Procedure #{subp.name}"
    args = subp.arguments
    args.each { |arg|
      puts "Argument #{arg.name}, type: #{arg.data_type}, in/out: #{arg.iomode.to_s}"
    }
  end
}
conn.logoff

Result:

Package Name: EMP_PKG
Subprogram:  Function GET_EMAIL
  Return Type: varchar2
  Argument 1: EMP_ID, Type: number
Subprogram:  Procedure GET_NAME
  Argument EMP_ID, type: number, in/out: in
  Argument EMP_NAME, type: varchar2, in/out: out

4.5 Describe Type

Type definition:

CREATE OR REPLACE TYPE person_t AS object
  (name varchar2(30),
  age number(3));

Describe via Ruby-OCI8

require 'oci8'
conn = OCI8.new('ruby','oci8','localhost')
person_t = conn.describe_type('person_t')
puts "Type Name: #{person_t.obj_name}"
person_t.type_attrs.each { |attr|
  puts "  Attribute #{attr.name}, type: #{attr.data_type}, size: #{attr.data_siz  e}"}
conn.logoff

Result:

Type Name: PERSON_T
  Attribute NAME, type: varchar2, size: 30
  Attribute AGE, type: number, size: 22

5, Reference

Describing Schema Metadata on Oracle Call Interface Programmer's Guide

Ruby-OCI8 2.0 New Feature: Array DML Support

2008-05-03T23:29:00.000-07:00

1, Introduction To Array DML

Oracle Call Interface provides an Array Interface. This array interface significantly reduces round trips to the database when you are updating or inserting a large volume of data. This reduction can lead to considerable performance gains in a busy client/server environment. For example, consider an application that needs to insert 100 rows into the database. Calling OCIStmtExecute() 100 times with single values results in 100 network round trips to insert all the data. The same result is possible with a single call to OCIStmtExecute() using an input array, which involves only one network round trip.

2, Ruby-OCI8 v2.0 Installation

svn co http://ruby-oci8.rubyforge.org/svn/trunk/ruby-oci8

And then follow the Ruby-OCI8 install instruction.

3, Usage

Three new instance methods are added to class OCI8::Cursor for supporting array dml:

1) max_array_size = val

Set the maximum array size for bind_param_array. This method should be called before bind_param_array.

example:

cursor = conn.parse("INSERT INTO test VALUES(:name, :age)")
cursor.max_array_size = 3
cursor.bind_param_array(:name, ['mike', 'john', 'danny'])
cursor.bind_param_array (:age, [20, 21, 22])
cursor.exec_array

When calling this method, all the binds will be clean from cursor if instance variable max_array_size of cursor is set before.

example:

cursor = conn.parse("INSERT INTO test VALUES(:name, :age)")
cursor.max_array_size = 3
cursor.bind_param_array(:name, ['mike', 'john', 'danny'])
cursor.bind_param_array(:age, [20, 21, 22])
cursor.max_array_size = 4
cursor.exec_array

Above example will generate an exception because you don't re-bind the params after calling max_array_size.

2) bind_param_array(key, var_array, type = nil, max_item_length = nil)

Bind array explicitly. This method is used to bind an array of values to a placeholder embedded in the prepared statement which is to be executed with "exec_array".

When key is number, it binds by position, which starts from 1. When key is string, it binds by the name of placeholder.

Example:

cursor = conn.parse("INSERT INTO test VALUES(:name)")
cursor.max_array_size = 3
cursor.bind_param_array(:name, ['mike', 'john', 'danny']) #bind by name
... or ...
cursor.bind_param_array(1, ['mike', 'john', 'danny']) #bind by position

The size of arrays bound through bind_param_array should not be greater than the size set by method max_array_size = val.

Example:

cursor = conn.parse("INSERT INTO test VALUES(:name)")
cursor.max_array_size = 2
cursor.bind_param_array(:name, ['mike', 'john', 'danny'])
cursor.exec_array

Above example will generate an exception because the size of array passed to bind_param_array is 3, which is greater than the size 2 set by max_array_size.

If you are binding more than one parameters, all the arrays are required the same size.

Example:

cursor = conn.parse("INSERT INTO test VALUES(:name, :age)")
cursor.max_array_size = 3
cursor.bind_param_array(:name, ['mike', 'john', 'danny'])
cursor.bind_param_array(:age, [20, 21])
cursor.exec_array

Above example will generate an exception becase the name parameter array and age parameter array are not the same size.

The array dml also supports setting values through method "[key] = val".

Example:

cursor = conn.parse("INSERT INTO test VALUES(:name, :age)")
cursor.max_array_size = 3
cursor.bind_param_array(1, nil, String)
cursor.bind_param_array(2, nil, Fixnum)
cursor[1] = ['mike', 'john', 'danny']
cursor[2] = [20, 21, 22]
cursor.exec_array

3) exec_array

Executes the SQL statement assigned the cursor with array binding. This implementation currently only supports non-data returning statements (INSERT, UPDATE, DELETE but not SELECT). All binding arrays should be the same size and this size will be used as iteration count for OCIStmtExecute().

Example:

cursor = conn.parse("INSERT INTO test VALUES(:name, :age)")
cursor.max_array_size = 10
cursor.bind_param_array(1, nil, String)
cursor.bind_param_array(2, nil, Fixnum)
cursor[1] = ['mike', 'john', 'danny']
cursor[2] = [20, 21, 22]
cursor.exec_array

In above example, three rows are inserted to the table though max_array_size is set 10.

Ruby-OCI8 2.0 New Feature: Oracle Object Type support

2008-04-25T02:13:00.000-07:00

There are two main versions in Ruby-OCI8. Stable version 1.x has been widely used in Ruby and RoR apps, and the unstable version is 2.x, in which many new features are under experiment. Here I will give a short tutorial on how to manipulates Object Type via Ruby-OCI8 v2.0.

1, Introduction to Oracle Object Type

Object types are abstractions of the real-world entities, such as purchase orders, that application programs deal with. An object type is a schema object with three kinds of components:

A name, which identifies the object type uniquely within that schema.
Attributes, which are built-in types or other user-defined types. Attributes model the structure of the real-world entity.
Methods, which are functions or procedures written in PL/SQL and stored in the database, or written in a language like C or Java and stored externally. Methods implement operations the application can perform on the real-world entity.

Learn more at Oracle® Database SQL Language Reference

2, Ruby-OCI8 v2.0 Installation

svn co http://ruby-oci8.rubyforge.org/svn/trunk/ruby-oci8

And then follow the Ruby-OCI8 install instruction.

3, Tutorial

Suppose we use account ruby/oci8 on an Oracle db installed on localhost

Step 1, Create object type and table in database

CREATE TYPE person_t AS object
   (name varchar2(30),
   age number(3));

CREATE TABLE person_tab
   (person_no number,
   person person_t);

Step 2, Insert sample data

INSERT INTO person_tab VALUES (1, person_t('Lan', 20));
INSERT INTO person_tab VALUES (2, person_t('Chang', 21));

Step 3, Retrieve object type data via Ruby-OCI8

require 'oci8'
conn = OCI8.new('ruby','oci8','localhost')
cursor = conn.exec('select * from person_tab')
while r = cursor.fetch
   puts "Person no: #{r[0]}"
   puts "  name: #{r[1].name}"
   puts "  age: #{r[1].age}"
end
cursor.close
conn.logoff

Result:

Person No.: 1
   name: Lan
   age: 20
Person NO.: 2
   name: Change
   age: 21

As we see, once we have retrieved an Object Type object in Ruby, we can use .{AttributeName} to get its specific attribute value stored in database.