Martin Fowler

https://martinfowler.com
Admin
A website dedicated to software development best practices, covering topics including refactoring,...
Tokens:1,167,230
Snippets:19,575
Trust Score:9.7
Update:3 months ago
Show doc for...
Tokens:
Raw
### Setup for Reversal Adjustment Example (Java)

Source: https://martinfowler.com/eaaDev/ReversalAdjustment.html

Initializes customer data and processes usage events, including setting up for a subsequent adjustment.

```java
public void setUp() {
    MfDate.setToday(2004,4,1);
    watson = new Customer("Dr Watson");
    watson.setServiceAgreement(testAgreement());
    usageEvent = new Usage(Unit.KWH.amount(50),
                 new MfDate(2004, 3, 31),
                 watson);
    eventList.add(usageEvent);
    eventList.process();
    MfDate.setToday(2004,6,1);
    replacement = new Usage(Unit.KWH.amount(70),
                    new MfDate(2004, 3, 31),
                    watson,
                    usageEvent);
    eventList.add(replacement);
    eventList.process();
}
```

--------------------------------

### Simple Service Agreement Setup

Source: https://martinfowler.com/eaaDev/AgreementDispatcher.html

Creates a basic ServiceAgreement, sets a default rate, and adds the MultiplyByRatePR posting rule for USAGE events. This is used for testing or simple examples.

```java
private ServiceAgreement simpleAgreement() {
    ServiceAgreement result = new ServiceAgreement();
    result.setRate(10, MfDate.PAST);
    result.addPostingRule(EventType.USAGE,
            new MultiplyByRatePR(AccountType.BASE_USAGE, false),
            new MfDate(1999, 10, 1));
    return result;
}
```

--------------------------------

### Setup and Teardown for Integration Tests

Source: https://martinfowler.com/articles/dependency-composition.html

This code block sets up the necessary database and server instances before each test and tears them down afterward. It populates the database with users, restaurants, and ratings, and starts the application server. This ensures a clean and consistent environment for integration tests.

```typescript
  describe("the restaurants endpoint", () => {
    let app: Server | undefined;
    let database: Database | undefined;
  
    const users = [
      { id: "u1", name: "User1", trusted: true },
      { id: "u2", name: "User2", trusted: false },
      { id: "u3", name: "User3", trusted: false },
    ];
  
    const restaurants = [
      { id: "cafegloucesterid", name: "Cafe Gloucester" },
      { id: "burgerkingid", name: "Burger King" },
    ];
  
    const ratingsByUser = [
      ["rating1", users[0], restaurants[0], "EXCELLENT"],
      ["rating2", users[1], restaurants[0], "TERRIBLE"],
      ["rating3", users[2], restaurants[0], "AVERAGE"],
      ["rating4", users[2], restaurants[1], "ABOVE_AVERAGE"],
    ];
  
    beforeEach(async () => {
      database = await DB.start();
      const client = database.getClient();
  
      await client.connect();
      try {
        // GIVEN
        // These functions don't exist yet, but I'll add them shortly
        for (const user of users) {
          await createUser(user, client);
        }
  
        for (const restaurant of restaurants) {
          await createRestaurant(restaurant, client);
        }
  
        for (const rating of ratingsByUser) {
          await createRatingByUserForRestaurant(rating, client);
        }
      } finally {
        await client.end();
      }
  
      app = await server.start(() =>
        Promise.resolve({
          serverPort: 3000,
          ratingsDB: {
            ...DB.connectionConfiguration,
            port: database?.getPort(),
          },
        }),
      );
    });
  
    afterEach(async () => {
      await server.stop();
      await database?.stop();
    });
  
    it("ranks by the recommendation heuristic", async () => {
      // .. snip

```

--------------------------------

### Solution: Overriding the Calling Method

Source: https://martinfowler.com/bliki/CallSuper.html

Demonstrates an alternative solution where the derived framework overrides the 'runBare' method to include its own setup logic before calling the original 'setUp'. This allows users to continue using the familiar 'setUp' method.

```java
public class AlphaTestCase extends TestCase...
  public void runBare() throws Throwable {
    alphaProjectSetup();
    setUp();
    try {
      runTest();
    }
    finally {
      tearDown();
    }
  }
  protected void setUp() throws Exception {
  }


```

--------------------------------

### Install Java Package and Configure Alternatives

Source: https://martinfowler.com/bliki/DebianJava.html

This sequence installs the `java-package` tool, builds a Debian package from the Sun JDK binary, installs the package, and configures the system's default Java version using `update-alternatives`.

```bash
# apt-get install java-package
download the sun jdk from java.sun.com
# make-jpkg jdk-1_5_0-linux-i586.bin
# dpkg -i sun-j2sdk1.5_1.5.0_i386.deb
# apt-get install sun-j2sdk1.5debian
# update-alternatives --config java

```

--------------------------------

### Alternative Java Installation Procedure

Source: https://martinfowler.com/bliki/DebianJava.html

An alternative method for installing Java on Debian, involving downloading the binary JDK, installing `java-package`, creating the Debian package using `fakeroot`, installing the package, and verifying the version.

```bash
//download bin jdk from Sun
#apt-get install java-package
//exit root and login with normal user:
#fakeroot make-jpkg jdk-1_5_0_06-linux-i586.bin
//su again:
#dpkg -i sun-j2sdk1.5_1.5.0+update06_i386.deb
#update-alternatives --config java
# java -version
//The latter just to check

```

--------------------------------

### Install Node.js, npm, and Coffee-Script

Source: https://martinfowler.com/articles/vagrant-chef-rbenv.html

Installs Node.js and npm, then globally installs a specific version of coffee-script using npm. Includes a symbolic link for the 'node' command.

```ruby
%w[nodejs npm].each {|p| package p}

execute "node-packages" do
  command "npm install -g coffee-script@1.6.3"
end

# annoyingly mac and ubuntu use different commands for node
link "/usr/bin/node" do
  to  "/usr/bin/nodejs"
end
```

--------------------------------

### XML Configuration Example

Source: https://martinfowler.com/articles/codeGenDsl.html

An example of a ReaderConfiguration represented in XML format. This allows for an alternative concrete syntax for the DSL.

```xml
<ReaderConfiguration>
  <Mapping Code = "SVCL" TargetClass = "dsl.ServiceCall">
    <Field name = "CustomerName" start = "4" end = "18"/>
    <Field name = "CustomerID" start = "19" end = "23"/>
    <Field name = "CallTypeCode" start = "24" end = "27"/>
    <Field name = "DateOfCallString" start = "28" end = "35"/>
  </Mapping>
  <Mapping Code = "USGE" TargetClass = "dsl.Usage">
    <Field name = "CustomerID" start = "4" end = "8"/>
    <Field name = "CustomerName" start = "9" end = "22"/>
    <Field name = "Cycle" start = "30" end = "30"/>
    <Field name = "ReadDate" start = "31" end = "36"/>
  </Mapping>
</ReaderConfiguration>
```

--------------------------------

### jQuery Getter and Setter Example

Source: https://martinfowler.com/bliki/OverloadedGetterSetter.html

Demonstrates how jQuery uses a single method for both getting and setting element properties. Use without arguments to get, with an argument to set.

```javascript
$( "#banner" ).height()
```

```javascript
$( "#banner" ).height(100)
```

--------------------------------

### Initialize Project and Add Dependencies

Source: https://martinfowler.com/articles/build-own-coding-agent.html

Use 'uv' to initialize a new project and add 'pydantic-ai' and 'boto3' as dependencies.

```bash
uv init
uv add pydantic_ai
uv add boto3
```

--------------------------------

### Applying Database Migrations with Flyway

Source: https://martinfowler.com/articles/evodb.html

This example demonstrates how to use the Flyway command-line tool to apply database migrations. It shows the output of the 'migrate' command, including database connection details, validation of existing migrations, creation of the metadata table, and the process of migrating the schema through various versions.

```bash
psadalag:flyway-4 $ ./flyway migrate
Flyway 4.0.3 by Boxfuse

Database: jdbc:oracle:thin:@localhost:1521:xe (Oracle 11.2)
Successfully validated 9 migrations (execution time 00:00.021s)
Creating Metadata table: "JEN_DEV"."schema_version"
Current version of schema "JEN_DEV": << Empty Schema >>
Migrating schema "JEN_DEV" to version 0 - base version
Migrating schema "JEN_DEV" to version 1 - asset
Migrating schema "JEN_DEV" to version 2 - asset type
Migrating schema "JEN_DEV" to version 3 - asset parameters
Migrating schema "JEN_DEV" to version 4 - inventory
Migrating schema "JEN_DEV" to version 5 - split inventory
Migrating schema "JEN_DEV" to version 6 - equipment type
Migrating schema "JEN_DEV" to version 7 - add insurance value to equipment type
Migrating schema "JEN_DEV" to version 8 - data location equipment type
Successfully applied 9 migrations to schema "JEN_DEV" (execution time 00:00.394s).
psadalag:flyway-4 $ 

```

--------------------------------

### Example JSON for Creative Matrix Generation

Source: https://martinfowler.com/articles/building-boba.html

Provide a detailed, few-shot example of the desired JSON output structure to guide the LLM. This is particularly effective for complex, multi-dimensional data like a creative matrix, ensuring context is maintained for each generated idea.

```json
You will respond with a valid JSON array, by row by column by idea. For example:

If Rows = "row 0, row 1" and Columns = "column 0, column 1" then you will respond
with the following:

[
  {{
    "row": "row 0",
    "columns": [
      {{
        "column": "column 0",
        "ideas": [
          {{
            "title": "Idea 0 title for prompt and row 0 and column 0",
            "description": "idea 0 for prompt and row 0 and column 0"
          }}
        ]
      }},
      {{
        "column": "column 1",
        "ideas": [
          {{
            "title": "Idea 0 title for prompt and row 0 and column 1",
            "description": "idea 0 for prompt and row 0 and column 1"
          }}
        ]
      }},
    ]
  }},
  {{
    "row": "row 1",
    "columns": [
      {{
        "column": "column 0",
        "ideas": [
          {{
            "title": "Idea 0 title for prompt and row 1 and column 0",
            "description": "idea 0 for prompt and row 1 and column 0"
          }}
        ]
      }},
      {{
        "column": "column 1",
        "ideas": [
          {{
            "title": "Idea 0 title for prompt and row 1 and column 1",
            "description": "idea 0 for prompt and row 1 and column 1"
          }}
        ]
      }}
    ]
  }}
]


```

--------------------------------

### HTTP Request with Access Token

Source: https://martinfowler.com/articles/command-line-google.html

This is an example of an HTTP GET request to a Google API endpoint, including the necessary Authorization header with an access token.

```http
GET /plus/v1/people/me HTTP/1.1
Authorization: Bearer 1/fFBGRNJru1FQd44AzqT3Zg
Host: googleapis.com


```

--------------------------------

### Setup for Single Electricity Usage Adjustment (Java)

Source: https://martinfowler.com/eaaDev/DifferenceAdjustment.html

Initializes customer data, original usage event, and sets up the DifferenceAdjustment for a single event. Ensure MfDate is set correctly before processing.

```java
public void setUp() {
      MfDate.setToday(2004, 4, 1);
      watson = sampleCustomer();
      original = new Usage(Unit.KWH.amount(50),
                           new MfDate(2004, 3, 31),
                           watson);
      eventList.add(original);
      eventList.process();
      MfDate.setToday(2004, 6, 1);
      replacement = new Usage(Unit.KWH.amount(70),
                              new MfDate(2004, 3, 31),
                              watson);
      adjustment = new DifferenceAdjustment(replacement, original);
      eventList.add(adjustment);
      eventList.process();
  }
```

--------------------------------

### JavaScript Getter/Setter Convention Example

Source: https://martinfowler.com/tags/2011.html

Illustrates the JavaScript convention of using the same function for getting and setting a property, similar to Smalltalk. This pattern is used in libraries like jQuery.

```javascript
 $("#banner").height()
 $("#banner").height(100)
```

--------------------------------

### End-to-End Test with Spring Boot and Selenium

Source: https://martinfowler.com/articles/practical-test-pyramid.html

A Java example demonstrating an end-to-end test using Spring Boot, Selenium WebDriver, and ChromeDriver. Ensure Chrome is installed on the system where the test is run.

```java
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class HelloE2ESeleniumTest {

    private WebDriver driver;

    @LocalServerPort
    private int port;

    @BeforeClass
    public static void setUpClass() throws Exception {
        ChromeDriverManager.getInstance().setup();
    }

    @Before
    public void setUp() throws Exception {
        driver = new ChromeDriver();
    }

    @After
    public void tearDown() {
        driver.close();
    }

    @Test
    public void helloPageHasTextHelloWorld() {
        driver.get(String.format("http://127.0.0.1:%s/hello", port));

        assertThat(driver.findElement(By.tagName("body")).getText(), containsString("Hello World!"));
    }
}
```

--------------------------------

### Install Apache and Link HTML Directory with Chef

Source: https://martinfowler.com/articles/vagrant-chef-rbenv.html

Installs the apache2 package and creates a symbolic link for the web root. Use the execute resource to overwrite existing directories.

```ruby
package "apache2"
  
  execute "set-html_dir" do
    command "rm -r /var/www/html; ln -s #{helper.html} /var/www/html"
  end

```

--------------------------------

### REST API Controller Example

Source: https://martinfowler.com/articles/practical-test-pyramid.html

A Spring Boot controller that handles GET requests to retrieve a person's greeting based on their last name. It demonstrates basic REST API functionality.

```java
@RestController
public class ExampleController {
    private final PersonRepository personRepository;

    // shortened for clarity

    @GetMapping("/hello/{lastName}")
    public String hello(@PathVariable final String lastName) {
        Optional<Person> foundPerson = personRepository.findByLastName(lastName);

        return foundPerson
             .map(person -> String.format("Hello %s %s!",
                     person.getFirstName(),
                     person.getLastName()))
             .orElse(String.format("Who is this '%s' you're talking about?",
                     lastName));
    }
}
```

--------------------------------

### Go: Render Initial HTML Model

Source: https://martinfowler.com/articles/tdd-html-templates.html

Initializes a todo list model with two items and renders it into an HTML template.

```go
model := todo.NewList().
  Add("One").
  Add("Two")
initialHtml := renderTemplate("index.tmpl", model, "/")
```

--------------------------------

### Import Statement Data Creation in JavaScript

Source: https://martinfowler.com/articles/refactoring-video-store-js

This example demonstrates how to import the `createStatementData` function from a separate module. It shows the setup for using the refactored data creation logic within statement generation functions.

```javascript
import createStatementData from './createStatementData.es6';
  function htmlStatement(customer, movies) { … }
  function statement(customer, movies) { … }
```

--------------------------------

### Implement Pact Provider Test for Spring

Source: https://martinfowler.com/articles/practical-test-pyramid.html

This example demonstrates a basic provider test setup using Pact for a Spring REST API. It configures the provider name, pact file location, and mocks dependencies. The `@State` annotation is used to define the expected state of the provider for a given test scenario.

```java
@RunWith(RestPactRunner.class)
@Provider("person_provider")// same as in the "provider_name" part in our pact file
@PactFolder("target/pacts") // tells pact where to load the pact files from
public class ExampleProviderTest {

    @Mock
    private PersonRepository personRepository;

    @Mock
    private WeatherClient weatherClient;

    private ExampleController exampleController;

    @TestTarget
    public final MockMvcTarget target = new MockMvcTarget();

    @Before
    public void before() {
        initMocks(this);
        exampleController = new ExampleController(personRepository, weatherClient);
        target.setControllers(exampleController);
    }

    @State("person data") // same as the "given()" part in our consumer test
    public void personData() {
        Person peterPan = new Person("Peter", "Pan");
        when(personRepository.findByLastName("Pan")).thenReturn(Optional.of
                (peterPan));
    }
}
```

--------------------------------

### Initialize MCPServerStdio for AWS Labs Core

Source: https://martinfowler.com/articles/build-own-coding-agent.html

Sets up an MCPServerStdio instance for AWS Labs core functionalities using 'uvx' and specifying the 'awslabs.core-mcp-server@latest' package. Error logging is configured.

```python
awslabs = MCPServerStdio(
    command="uvx",
    args=["awslabs.core-mcp-server@latest"],
    env={"FASTMCP_LOG_LEVEL": "ERROR"},
    tool_prefix="awslabs",
)
```

--------------------------------

### Bootstrap Script for Ruby and Bundler Installation

Source: https://martinfowler.com/articles/vagrant-chef-rbenv.html

A shell script to install a specific Ruby version using rbenv if not already present, install bundler, and then install project gems.

```shell
read -r VERSION < mfcom/.ruby-version
if [ -f .rbenv/versions/${VERSION}/bin/ruby ]; then
  echo "ruby ${VERSION} is already installed"
else
  rbenv install $VERSION
fi
cd mfcom
gem install bundler --no-rdoc --no-ri
rbenv rehash
bundle install --without=mac

```

--------------------------------

### Initialize MCPServerStdio for Context7

Source: https://martinfowler.com/articles/build-own-coding-agent.html

Sets up an MCPServerStdio instance for Context7 using npx to execute the '@upstash/context7-mcp' package.

```python
context7 = MCPServerStdio(command="npx", args=["-y", "@upstash/context7-mcp"], tool_prefix="context")
```

--------------------------------

### JUnit setUp Method for Reinitialization

Source: https://martinfowler.com/bliki/JunitNewInstance.html

Demonstrates the use of the `setUp` method in JUnit to reinitialize test state before each test method runs. This supports test isolation.

```java
  public void setUp() {
    list = new ArrayList();
  }
	
```

--------------------------------

### Configuring a Dynamic Service Locator

Source: https://martinfowler.com/articles/injection.html

Demonstrates how to configure the dynamic service locator by loading specific services with appropriate keys. Ensure the ServiceLocator class is loaded before use.

```java
private void configure() {
    ServiceLocator locator = new ServiceLocator();
    locator.loadService("MovieFinder", new ColonMovieFinder("movies1.txt"));
    ServiceLocator.load(locator);
}
```

--------------------------------

### Install VMWare dependencies on Ubuntu

Source: https://martinfowler.com/bliki/HotRod.html

Installs necessary development tools like 'make' and 'gcc-3.4', and kernel headers required for VMWare installation on Ubuntu.

```bash
sudo apt-get install make
sudo apt-get install gcc-3.4
sudo apt-get install linux-headers-amd64-generic

```

--------------------------------

### Example JSON Order Document

Source: https://martinfowler.com/bliki/EmbeddedDocument.html

An example of a JSON document representing an order with items and deliveries.

```json
{ "id": 1234,
  "customer": "martin",
  "items": [
    {"product": "talisker", "quantity": 500},
    {"product": "macallan", "quantity": 800},
    {"product": "ledaig",   "quantity": 1100}
  ],
  "deliveries": [
    { "id": 7722,
      "shipDate": "2013-04-19",
      "items": [
        {"product": "talisker", "quantity": 300},
        {"product": "ledaig",   "quantity": 500}
      ]
    },
    { "id": 6533,
      "shipDate": "2013-04-18",
      "items": [
        {"product": "talisker", "quantity": 200},
        {"product": "ledaig",   "quantity": 300},
        {"product": "macallan", "quantity": 300}
      ]
    }
  ]
}
```
Tokens:
Raw