Initial commit

.gitattributes

@@ -0,0 +1,3 @@
+/gradlew text eol=lf
+*.bat text eol=crlf
+*.jar binary

.gitignore

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+HELP.md
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Kotlin ###
+.kotlin

build.gradle.kts

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+plugins {
+    kotlin("jvm") version "1.9.25"
+    kotlin("plugin.spring") version "1.9.25"
+    id("org.springframework.boot") version "3.5.5"
+    id("io.spring.dependency-management") version "1.1.7"
+}
+
+group = "ltd.lulz"
+version = "0.0.1-SNAPSHOT"
+description = "basic banking"
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(17)
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation("io.github.oshai:kotlin-logging-jvm:7.0.7")
+    implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
+    implementation("io.projectreactor.kotlin:reactor-kotlin-extensions")
+    implementation("org.jetbrains.kotlin:kotlin-reflect")
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-reactor")
+    implementation("org.springframework.boot:spring-boot-starter-data-r2dbc")
+    implementation("org.springframework.boot:spring-boot-starter-webflux")
+
+    testImplementation("io.mockk:mockk:1.14.5")
+    testImplementation("io.projectreactor:reactor-test")
+    testImplementation("org.jetbrains.kotlin:kotlin-test-junit5")
+    testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-test")
+    testImplementation("org.springframework.boot:spring-boot-starter-test")
+
+    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
+}
+
+kotlin {
+    compilerOptions {
+        freeCompilerArgs.addAll("-Xjsr305=strict")
+    }
+}
+
+tasks.withType<Test> {
+    useJUnitPlatform()
+}

gradle/wrapper/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14.3-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

gradlew

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+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s\n' "$PWD" ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH="\\\"\\\""
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

gradlew.bat

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+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+@rem SPDX-License-Identifier: Apache-2.0
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

instructions.md

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+# Senior Engineer Test
+
+### **Develop a service that simulates basic banking operations in a programming language of your choice. This service will manage accounts, process deposits, withdrawals, and transfers between accounts.**
+
+### The system should be designed reflecting real-world constraints of a bank.
+
+## Requirements:
+
+1. A class or set of functions that allow:
+   * Account creation: Allow users to create an account with an initial deposit.
+   * Deposit: Enable users to deposit money into their account.
+   * Withdrawal: Allow users to withdraw money from their account, ensuring that overdrafts are not allowed.
+   * Transfer: Enable transferring funds between accounts.
+   * Account balance: Provide the ability to check the account balance.
+2. Database:
+   * In-memory data storage will suffice, no need to have a database alongside the project, but you can add one at your discretion
+
+The word “service” here is used in a “software component/module” rather “deployable unit with an API” sense, no need to provide API for it.
+
+## Feel free to take as along as you need to complete the exercise. This will be used as a base for a follow-up pair programming session.

settings.gradle.kts

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+rootProject.name = "basic-banking"

src/test-integration/kotlin/ltd/lulz/AccountEndpoints.kt

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+package ltd.lulz
+
+import java.math.BigDecimal
+import java.util.UUID
+import ltd.lulz.model.Account
+import ltd.lulz.test.container.PostgresTestContainer
+import org.assertj.core.api.SoftAssertions
+import org.assertj.core.api.junit.jupiter.InjectSoftAssertions
+import org.assertj.core.api.junit.jupiter.SoftAssertionsExtension
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.ExtendWith
+import org.springframework.boot.test.context.SpringBootTest
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT
+import org.springframework.boot.test.web.server.LocalServerPort
+import org.springframework.http.HttpStatus.BAD_REQUEST
+import org.springframework.http.HttpStatus.CREATED
+import org.springframework.http.HttpStatus.NOT_FOUND
+import org.springframework.http.HttpStatus.OK
+import org.springframework.test.web.reactive.server.WebTestClient
+import org.springframework.test.web.reactive.server.expectBody
+
+@PostgresTestContainer
+@SpringBootTest(webEnvironment = RANDOM_PORT)
+@ExtendWith(SoftAssertionsExtension::class)
+class AccountEndpoints {
+
+    @InjectSoftAssertions
+    lateinit var softly: SoftAssertions
+
+    @LocalServerPort
+    var port: Int = 0
+
+    lateinit var webClient: WebTestClient
+
+    @BeforeEach
+    fun setup() {
+        webClient = WebTestClient.bindToServer().baseUrl("http://localhost:$port").build()
+    }
+
+    @Test
+    fun `create account - success add account to db`() {
+        // given
+        val request = Account.Request(
+            name = "user",
+            amount = BigDecimal.valueOf(10.01),
+        )
+
+        // when
+        val result = webClient.post()
+            .uri("/account")
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(CREATED)
+            .expectBody<Account.Response>()
+            .consumeWith {
+                softly.assertThat(it.responseBody?.id?.version()).isEqualTo(7)
+                softly.assertThat(it.responseBody?.name).isEqualTo("user")
+                softly.assertThat(it.responseBody?.amount).isEqualTo("10.01")
+            }
+    }
+
+    @Test
+    fun `create account - fail amount to small`() {
+        // given
+        val request = Account.Request(
+            name = "user",
+            amount = BigDecimal.valueOf(0.009),
+        )
+
+        // when
+        val result = webClient.post()
+            .uri("/account")
+            .bodyValue(request)
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(BAD_REQUEST)
+    }
+
+    @Test
+    fun `get balance - success get balance from db`() {
+        // given
+        val user1 = UUID.fromString("00000000-0000-7000-0000-000000000001")
+
+        // when
+        val result = webClient.get()
+            .uri("/balance/account-$user1")
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(OK)
+            .expectBody<Account.Response>()
+            .consumeWith {
+                softly.assertThat(it.responseBody?.id).isEqualTo(user1)
+                softly.assertThat(it.responseBody?.name).isEqualTo("user 1")
+                softly.assertThat(it.responseBody?.amount).isEqualTo("10.00")
+            }
+    }
+
+    @Test
+    fun `get balance - fail account not found`() {
+        // when
+        val result = webClient.get()
+            .uri("/balance/account-00000000-0000-7000-0000-000000000000")
+            .exchange()
+
+        // then
+        result.expectStatus().isEqualTo(NOT_FOUND)
+    }
+}

src/test-integration/kotlin/ltd/lulz/TransactionEndpoints.kt

@@ -0,0 +1,293 @@
+package ltd.lulz
+
+import java.math.BigDecimal
+import java.util.UUID
+import ltd.lulz.model.Transaction
+import ltd.lulz.model.Transfer
+import ltd.lulz.test.container.PostgresTestContainer
+import org.assertj.core.api.SoftAssertions
+import org.assertj.core.api.junit.jupiter.InjectSoftAssertions
+import org.assertj.core.api.junit.jupiter.SoftAssertionsExtension
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.ExtendWith
+import org.springframework.boot.test.context.SpringBootTest
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT
+import org.springframework.boot.test.web.server.LocalServerPort
+import org.springframework.http.HttpStatus.BAD_REQUEST
+import org.springframework.http.HttpStatus.CREATED
+import org.springframework.http.HttpStatus.NOT_ACCEPTABLE
+import org.springframework.http.HttpStatus.NOT_FOUND
+import org.springframework.test.web.reactive.server.WebTestClient
+
+@PostgresTestContainer
+@SpringBootTest(webEnvironment = RANDOM_PORT)
+@ExtendWith(SoftAssertionsExtension::class)
+class TransactionEndpoints {
+
+    @InjectSoftAssertions
+    lateinit var softly: SoftAssertions
+
+    @LocalServerPort
+    var port: Int = 0
+
+    lateinit var webClient: WebTestClient
+
+    @BeforeEach
+    fun setup() {
+        webClient = WebTestClient.bindToServer().baseUrl("http://localhost:$port").build()
+    }
+
+    @Nested
+    inner class DepositTest {
+
+        @Test
+        fun `deposit - success`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/deposit")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(CREATED)
+        }
+
+        @Test
+        fun `deposit - fail amount to small`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(0.009),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/deposit")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(BAD_REQUEST)
+        }
+
+        @Test
+        fun `deposit - fail account not found`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000000"),
+                amount = BigDecimal.valueOf(0.01),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/deposit")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_FOUND)
+        }
+    }
+
+    @Nested
+    inner class WithdrawalTest {
+
+        @Test
+        fun `deposit - success`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/withdrawal")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(CREATED)
+        }
+
+        @Test
+        fun `deposit - fail amount to small`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(0.009),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/withdrawal")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(BAD_REQUEST)
+        }
+
+        @Test
+        fun `deposit - fail account not found`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000000"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/withdrawal")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_FOUND)
+        }
+
+        @Test
+        fun `deposit - fail insufficient funds`() {
+            // given
+            val request = Transaction.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(100.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/withdrawal")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_ACCEPTABLE)
+        }
+    }
+
+    @Nested
+    inner class TransferTest {
+
+        @Test
+        fun `deposit - success`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000002"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(CREATED)
+        }
+
+        @Test
+        fun `deposit - fail same account`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(BAD_REQUEST)
+        }
+
+        @Test
+        fun `deposit - fail amount to small`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000002"),
+                amount = BigDecimal.valueOf(0.009),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(BAD_REQUEST)
+        }
+
+        @Test
+        fun `deposit - fail account not found`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000000"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000002"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_FOUND)
+        }
+
+        @Test
+        fun `deposit - fail receiver not found`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000000"),
+                amount = BigDecimal.valueOf(1.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_FOUND)
+        }
+
+        @Test
+        fun `deposit - fail insufficient funds`() {
+            // given
+            val request = Transfer.Request(
+                account = UUID.fromString("00000000-0000-7000-0000-000000000001"),
+                receiver = UUID.fromString("00000000-0000-7000-0000-000000000002"),
+                amount = BigDecimal.valueOf(100.00),
+            )
+
+            // when
+            val result = webClient.post()
+                .uri("/transfer")
+                .bodyValue(request)
+                .exchange()
+
+            // then
+            result.expectStatus().isEqualTo(NOT_ACCEPTABLE)
+        }
+    }
+}

src/test-integration/resources/postgres/data.sql

@@ -0,0 +1,3 @@
+INSERT INTO public.accounts(id, name, amount)
+VALUES ('00000000-0000-7000-0000-000000000001'::uuid, 'user 1', 10.0),
+       ('00000000-0000-7000-0000-000000000002'::uuid, 'user 2', 10.0);

src/test-integration/resources/postgres/reset.sql

@@ -0,0 +1 @@
+TRUNCATE TABLE accounts CASCADE;

src/test-integration/resources/postgres/schema.sql

@@ -0,0 +1,7 @@
+CREATE TABLE IF NOT EXISTS public.accounts
+(
+    id   UUID DEFAULT uuidv7(),
+    name VARCHAR(50) NOT NULL,
+    amount  NUMERIC(19, 2) NOT NULL,
+    CONSTRAINT pk_contact_types PRIMARY KEY (id)
+);