Kotlin -> custom-set

kotlin/custom-set/.exercism/metadata.json

@@ -0,0 +1 @@
+{"track":"kotlin","exercise":"custom-set","id":"bae351839e7547ebb21a6dbc840e2b04","url":"https://exercism.io/my/solutions/bae351839e7547ebb21a6dbc840e2b04","handle":"anthonycicc","is_requester":true,"auto_approve":false}

kotlin/custom-set/.gradle/buildOutputCleanup/cache.properties

@@ -0,0 +1,2 @@
+#Sat Mar 07 17:31:28 EST 2020
+gradle.version=6.0.1

kotlin/custom-set/.idea/.gitignore

@@ -0,0 +1,8 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml
+# Editor-based HTTP Client requests
+/httpRequests/

kotlin/custom-set/.idea/compiler.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CompilerConfiguration">
+    <bytecodeTargetLevel target="13" />
+  </component>
+</project>

kotlin/custom-set/.idea/jarRepositories.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RemoteRepositoriesConfiguration">
+    <remote-repository>
+      <option name="id" value="central" />
+      <option name="name" value="Maven Central repository" />
+      <option name="url" value="https://repo1.maven.org/maven2" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="jboss.community" />
+      <option name="name" value="JBoss Community repository" />
+      <option name="url" value="https://repository.jboss.org/nexus/content/repositories/public/" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="BintrayJCenter" />
+      <option name="name" value="BintrayJCenter" />
+      <option name="url" value="https://jcenter.bintray.com/" />
+    </remote-repository>
+  </component>
+</project>

kotlin/custom-set/.idea/misc.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="FrameworkDetectionExcludesConfiguration">
+    <file type="web" url="file://$PROJECT_DIR$" />
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_13" default="false" />
+</project>

kotlin/custom-set/.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/../.." vcs="Git" />
+  </component>
+</project>

kotlin/custom-set/README.md

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+# Custom Set
+
+Create a custom set type.
+
+Sometimes it is necessary to define a custom data structure of some
+type, like a set. In this exercise you will define your own set. How it
+works internally doesn't matter, as long as it behaves like a set of
+unique elements.
+
+## Setup
+
+Go through the setup instructions for Kotlin to install the necessary
+dependencies:
+
+[https://exercism.io/tracks/kotlin/installation](https://exercism.io/tracks/kotlin/installation)
+
+## Making the test suite pass
+
+Execute the tests with:
+
+```bash
+$ ./gradlew test
+```
+
+> Use `gradlew.bat` if you're on Windows
+
+In the test suites all tests but the first have been skipped.
+
+Once you get a test passing, you can enable the next one by removing the
+`@Ignore` annotation.
+
+## Submitting Incomplete Solutions
+
+It's possible to submit an incomplete solution so you can see how others have
+completed the exercise.

kotlin/custom-set/build.gradle.kts

@@ -0,0 +1,23 @@
+import org.gradle.api.tasks.testing.logging.TestExceptionFormat
+
+plugins {
+    kotlin("jvm") version "1.3.60"
+}
+
+repositories {
+    jcenter()
+}
+
+dependencies {
+    compile(kotlin("stdlib"))
+    
+    testImplementation("junit:junit:4.12")
+    testImplementation(kotlin("test-junit"))
+}
+
+tasks.withType<Test> {
+    testLogging {
+        exceptionFormat = TestExceptionFormat.FULL
+        events("passed", "failed", "skipped")
+    }
+}

kotlin/custom-set/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.0.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

kotlin/custom-set/gradlew

@@ -0,0 +1,188 @@
+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or 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.
+#
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# 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: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"

kotlin/custom-set/gradlew.bat

@@ -0,0 +1,100 @@
+@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
+
+@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=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@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%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="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!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

kotlin/custom-set/src/main/kotlin/CustomSet.kt

@@ -0,0 +1,42 @@
+class CustomSet() {
+
+    var internals = mutableSetOf<Int>()
+
+    constructor(vararg stuff: Int): this() {
+        stuff.forEach { this.add(it) }
+    }
+
+    constructor(wrapped: Set<Int>): this() {
+        wrapped.forEach { this.add(it) }
+    }
+
+    fun isEmpty(): Boolean = internals.isEmpty()
+
+    fun isSubset(other: CustomSet): Boolean = other.internals.containsAll(internals)
+
+    fun isDisjoint(other: CustomSet): Boolean {
+        return if (this.internals.isNotEmpty() && other.internals.isNotEmpty()) {
+            other.internals.all { it !in this.internals }
+        } else true
+    }
+
+    fun contains(other: Int): Boolean = this.internals.contains(other)
+
+    fun intersection(other: CustomSet): CustomSet = CustomSet(other.internals.intersect(this.internals))
+
+    fun add(other: Int) {
+        internals.add(other)
+    }
+
+    override fun equals(other: Any?) = if (other is CustomSet) {
+        other.internals == internals
+    } else {
+        false
+    }
+
+    operator fun plus(other: CustomSet) = CustomSet(internals.plus(other.internals))
+
+    operator fun minus(other: CustomSet) = CustomSet(this.internals.minus(other.internals))
+
+    override fun hashCode() = javaClass.hashCode()
+}

kotlin/custom-set/src/test/kotlin/CustomSetTest.kt

@@ -0,0 +1,286 @@
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertNotEquals
+import kotlin.test.assertTrue
+
+class CustomSetTest {
+
+    @Test
+    fun `sets with no elements are empty`() {
+        val sut = CustomSet()
+        assertTrue(sut.isEmpty())
+    }
+
+    @Test
+    fun `sets with elements are not empty`() {
+        val sut = CustomSet(1)
+        assertFalse(sut.isEmpty())
+    }
+
+    @Test
+    fun `nothing is contained in an empty set`() {
+        val sut = CustomSet()
+        assertFalse(sut.contains(1))
+    }
+
+    @Test
+    fun `when the element is in the set`() {
+        val sut = CustomSet(1, 2, 3)
+        assertTrue(sut.contains(1))
+    }
+
+    @Test
+    fun `when the element is not in the set`() {
+        val sut = CustomSet(1, 2, 3)
+        assertFalse(sut.contains(4))
+    }
+
+    @Test
+    fun `empty set is a subset of another empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet()
+        assertTrue(set1.isSubset(set2))
+    }
+
+    @Test
+    fun `empty set is a subset of non empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet(1)
+        assertTrue(set1.isSubset(set2))
+    }
+
+    @Test
+    fun `non empty set is not a subset of empty set`() {
+        val set1 = CustomSet(1)
+        val set2 = CustomSet()
+        assertFalse(set1.isSubset(set2))
+    }
+
+    @Test
+    fun `set is a subset of set with exact same elements`() {
+        val set1 = CustomSet(1, 2, 3)
+        val set2 = CustomSet(1, 2, 3)
+        assertTrue(set1.isSubset(set2))
+    }
+
+    @Test
+    fun `set is a subset of larger set with same elements`() {
+        val set1 = CustomSet(1, 2, 3)
+        val set2 = CustomSet(4, 1, 2, 3)
+        assertTrue(set1.isSubset(set2))
+    }
+
+    @Test
+    fun `set is not a subset of set that does not contain its elements`() {
+        val set1 = CustomSet(1, 2, 3)
+        val set2 = CustomSet(4, 1, 3)
+        assertFalse(set1.isSubset(set2))
+    }
+
+    @Test
+    fun `the empty set is disjoint with itself`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet()
+        assertTrue(set1.isDisjoint(set2))
+    }
+
+    @Test
+    fun `empty set is disjoint with non empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet(1)
+        assertTrue(set1.isDisjoint(set2))
+    }
+
+    @Test
+    fun `non empty set is disjoint with empty set`() {
+        val set1 = CustomSet(1)
+        val set2 = CustomSet()
+        assertTrue(set1.isDisjoint(set2))
+    }
+
+    @Test
+    fun `sets are not disjoint if they share an element`() {
+        val set1 = CustomSet(1, 2)
+        val set2 = CustomSet(2, 3)
+        assertFalse(set1.isDisjoint(set2))
+    }
+
+    @Test
+    fun `sets are disjoint if they share no elements`() {
+        val set1 = CustomSet(1, 2)
+        val set2 = CustomSet(3, 4)
+        assertTrue(set1.isDisjoint(set2))
+    }
+
+    @Test
+    fun `empty sets are equal`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet()
+        assertEquals(set1, set2)
+    }
+
+    @Test
+    fun `empty set is not equal to non empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet(1, 2, 3)
+        assertNotEquals(set1, set2)
+    }
+
+    @Test
+    fun `non empty set is not equal to empty set`() {
+        val set1 = CustomSet(1, 2, 3)
+        val set2 = CustomSet()
+        assertNotEquals(set1, set2)
+    }
+
+    @Test
+    fun `sets with the same elements are equal`() {
+        val set1 = CustomSet(1, 2)
+        val set2 = CustomSet(2, 1)
+        assertEquals(set1, set2)
+
+    }
+
+    @Test
+    fun `sets with different elements are not equal`() {
+        val set1 = CustomSet(1, 2, 3)
+        val set2 = CustomSet(1, 2, 4)
+        assertNotEquals(set1, set2)
+    }
+
+    @Test
+    fun `set is not equal to larger set with same elements`() {
+        val set1 = CustomSet(1, 2, 3)
+        val set2 = CustomSet(1, 2, 3, 4)
+        assertNotEquals(set1, set2)
+    }
+
+    @Test
+    fun `add to empty set`() {
+        val sut = CustomSet()
+        val expected = CustomSet(3)
+        sut.add(3)
+        assertEquals(expected, sut)
+    }
+
+    @Test
+    fun `add to non empty set`() {
+        val sut = CustomSet(1, 2, 4)
+        val expected = CustomSet(1, 2, 3, 4)
+        sut.add(3)
+        assertEquals(expected, sut)
+    }
+
+    @Test
+    fun `adding an existing element does not change the set`() {
+        val sut = CustomSet(1, 2, 3)
+        val expected = CustomSet(1, 2, 3)
+        sut.add(3)
+        assertEquals(expected, sut)
+    }
+
+    @Test
+    fun `intersection of two empty sets is an empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet()
+        val expected = CustomSet()
+        assertEquals(expected, set1.intersection(set2))
+    }
+
+    @Test
+    fun `intersection of an empty set and non empty set is an empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet(3, 2, 5)
+        val expected = CustomSet()
+        assertEquals(expected, set1.intersection(set2))
+    }
+
+    @Test
+    fun `intersection of a non empty set and an empty set is an empty set`() {
+        val set1 = CustomSet(1, 2, 3, 4)
+        val set2 = CustomSet()
+        val expected = CustomSet()
+        assertEquals(expected, set1.intersection(set2))
+    }
+
+    @Test
+    fun `intersection of two sets with no shared elements is an empty set`() {
+        val set1 = CustomSet(1, 2, 3)
+        val set2 = CustomSet(4, 5, 6)
+        val expected = CustomSet()
+        assertEquals(expected, set1.intersection(set2))
+    }
+
+    @Test
+    fun `intersection of two sets with shared elements is a set of the shared elements`() {
+        val set1 = CustomSet(1, 2, 3, 4)
+        val set2 = CustomSet(3, 2, 5)
+        val expected = CustomSet(2, 3)
+        assertEquals(expected, set1.intersection(set2))
+    }
+
+    @Test
+    fun `difference of two empty sets is an empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet()
+        val expected = CustomSet()
+        assertEquals(expected, set1 - set2)
+    }
+
+    @Test
+    fun `difference of empty set and non empty set is an empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet(3, 2, 5)
+        val expected = CustomSet()
+        assertEquals(expected, set1 - set2)
+    }
+
+    @Test
+    fun `difference of a non empty set and an empty set is the non empty set`() {
+        val set1 = CustomSet(1, 2, 3, 4)
+        val set2 = CustomSet()
+        val expected = CustomSet(1, 2, 3, 4)
+        assertEquals(expected, set1 - set2)
+    }
+
+    @Test
+    fun `difference of two non empty sets is a set of elements that are only in the first set`() {
+        val set1 = CustomSet(3, 2, 1)
+        val set2 = CustomSet(2, 4)
+        val expected = CustomSet(1, 3)
+        assertEquals(expected, set1 - set2)
+    }
+
+    @Test
+    fun `union of empty sets is an empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet()
+        val expected = CustomSet()
+        assertEquals(expected, set1 + set2)
+    }
+
+    @Test
+    fun `union of an empty set and non empty set is the non empty set`() {
+        val set1 = CustomSet()
+        val set2 = CustomSet(2)
+        val expected = CustomSet(2)
+        assertEquals(expected, set1 + set2)
+    }
+
+    @Test
+    fun `union of a non empty set and empty set is the non empty set`() {
+        val set1 = CustomSet(1, 3)
+        val set2 = CustomSet()
+        val expected = CustomSet(1, 3)
+        assertEquals(expected, set1 + set2)
+    }
+
+    @Test
+    fun `union of non empty sets contains all unique elements`() {
+        val set1 = CustomSet(1, 3)
+        val set2 = CustomSet(2, 3)
+        val expected = CustomSet(3, 2, 1)
+        assertEquals(expected, set1 + set2)
+    }
+}