Merge pull request #3 from yonggzhou/add-usage-to-readme

Add usage to readme

README.md

@@ -18,6 +18,138 @@ database-evolution-test-utils is available on Maven Central.
 </dependency>
 ```
 
+### Example
+
+This example shows how we can use <b>database-evolution-test-utils</b> to test liquibase
+scripts for database migrations.
+
+#### Folder structure overview
+```text
+├── src
+│   ├── main
+│   │   ├── java
+│   │   └── resources
+│   │       ├── application.properties
+│   │       ├── migration-scripts.xml
+│   │       └── dbevolution
+│   │           └── CreateCustomerTable.xml
+│   └── test
+│       ├── java
+│       │   └── com
+│       │       └── tyro
+│       │           └── oss
+│       │               └── dbevolution
+│       │                   └── CreateCustomerTable.java
+│       │                   ├── LiquibaseScriptsTest.java
+│       └── resources
+│           └── schema.sql
+
+```
+
+The following in an example Changeset to create a table called <b>CustomerTable</b> with multiple columns.
+
+```xml
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
+                   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+                   xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
+   http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.6.xsd">
+
+    <changeSet id='20191114' author='author'>
+        <preConditions>
+            <not>
+                <tableExists tableName="CustomerTable"/>
+            </not>
+        </preConditions>
+
+        <createTable tableName="CustomerTable">
+            <column name="id" type="bigint" autoIncrement="true">
+                <constraints primaryKey="true" nullable="false"/>
+            </column>
+            <column name="name" type="varchar(255)">
+                <constraints nullable="false"/>
+            </column>
+        </createTable>
+
+
+    </changeSet>
+</databaseChangeLog>
+```
+
+Here's the associate liquibase Changelog file with the create table Changeset:
+
+```xml
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
+                   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+                   xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
+   http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.6.xsd">
+
+    <include file="dbevolution/CreateCustomerTable.xml" />
+
+</databaseChangeLog>
+
+```
+
+### Testing
+
+Here's how we test whether the Changesets are created correctly.
+
+Define <b>LiquibaseMigrationTestDefinition</b> for each Changeset.
+
+<b>NOTE</b>: It needs to be the <b>same name</b> as the one defined in 
+<b>migration-scripts.xml</b>, and also should be under the <b>same directory</b>, 
+<i>i.e. dbevolution/CreateCustomerTable.java</i>
+
+```java
+public class CreateCustomerTable extends LiquibaseMigrationTestDefinition {
+
+    @Override
+    protected void assertPreMigrationSchema(Database schema, Connection connection) {
+        assertThatSchema(schema, connection)
+                .doesNotHaveTable("CustomerTable");
+    }
+
+    @Override
+    protected void assertPostMigrationSchema(Database schema, Connection connection) {
+        assertThatSchema(schema, connection)
+                .hasTable("CustomerTable")
+                .enterNewTableAssertionMode()
+                    .hasColumn("id")
+                        .isPrimaryKeyIdColumn()
+                    .hasColumn("name")
+                        .supportsType(String.class)
+                        .isNotNullable();
+    }
+}
+
+```
+
+Creates test class that extends the <b>LiquibaseMigrationScriptTestBase</b> class, and include all the 
+<b>LiquibaseMigrationTestDefinitions</b> in it.
+
+```java
+@Testcontainers
+@SchemaDetails(
+        migrationUser = "username",
+        migrationPassword = "password",
+        url = "jdbc:tc:mysql://localhost/test?serverTimezone=UTC",
+        snapshotScript = "schema.sql")
+@MigrationScript(filename = "migration-scripts.xml")
+public class LiquibaseScriptsTest extends LiquibaseMigrationScriptTestBase {
+
+    @Container
+    private final MySQLContainer mysql = new MySQLContainer();
+
+    @Override
+    protected List<LiquibaseMigrationTestDefinition> testDefinitions() {
+        return asList(new CreateCustomerTable());
+    }
+}
+```
+
+That's it!!! Happy migrating!
+
 ## Copyright and Licensing
 
 Copyright (C) 2019 Tyro Payments Pty Ltd

src/test/java/com/tyro/oss/dbevolution/CreateExampleTable.java

@@ -36,10 +36,7 @@ protected void assertPostMigrationSchema(Database schema, Connection connection)
                 .hasTable("ExampleTable")
                 .enterNewTableAssertionMode()
                 .hasColumn("id")
-                    .supportsIdType()
-                    .isPrimaryKey()
-                    .isNotNullable()
-                    .isAutoIncrementing()
+                    .isPrimaryKeyIdColumn()
                 .hasColumn("column1")
                     .supportsType(String.class)
                     .isNullable()