diff --git a/common/logging/src/main/kotlin/net/corda/common/logging/errorReporting/ErrorReporting.kt b/common/logging/src/main/kotlin/net/corda/common/logging/errorReporting/ErrorReporting.kt
index b58557d67e..20cdb77cf6 100644
--- a/common/logging/src/main/kotlin/net/corda/common/logging/errorReporting/ErrorReporting.kt
+++ b/common/logging/src/main/kotlin/net/corda/common/logging/errorReporting/ErrorReporting.kt
@@ -43,6 +43,11 @@ class ErrorReporting private constructor(private val localeString: String,
         return ErrorReporting(localeString, location, contextProvider)
     }
 
+    /**
+     * Set the context provider to supply project-specific information about the errors.
+     *
+     * @param contextProvider The context provider to use with error reporting
+     */
     fun withContextProvider(contextProvider: ErrorContextProvider) : ErrorReporting {
         return ErrorReporting(localeString, resourceLocation, contextProvider)
     }
diff --git a/common/logging/src/main/kotlin/net/corda/common/logging/errorReporting/Errors.kt b/common/logging/src/main/kotlin/net/corda/common/logging/errorReporting/Errors.kt
index 83e324b893..95779d23d6 100644
--- a/common/logging/src/main/kotlin/net/corda/common/logging/errorReporting/Errors.kt
+++ b/common/logging/src/main/kotlin/net/corda/common/logging/errorReporting/Errors.kt
@@ -4,7 +4,8 @@ package net.corda.common.logging.errorReporting
  * Namespaces for errors within the node.
  */
 enum class NodeNamespaces {
-    DATABASE
+    DATABASE,
+    CORDAPP
 }
 
 /**
@@ -17,4 +18,16 @@ enum class NodeDatabaseErrors : ErrorCodes {
     PASSWORD_REQUIRED_FOR_H2;
 
     override val namespace = NodeNamespaces.DATABASE.toString()
+}
+
+/**
+ * Errors related to loading of Cordapps
+ */
+enum class CordappErrors : ErrorCodes {
+    DUPLICATE_CORDAPPS_INSTALLED,
+    MULTIPLE_CORDAPPS_FOR_FLOW,
+    MISSING_VERSION_ATTRIBUTE,
+    INVALID_VERSION_IDENTIFIER;
+
+    override val namespace = NodeNamespaces.CORDAPP.toString()
 }
\ No newline at end of file
diff --git a/common/logging/src/main/resources/error-codes/cordapp-duplicate-cordapps-installed.properties b/common/logging/src/main/resources/error-codes/cordapp-duplicate-cordapps-installed.properties
new file mode 100644
index 0000000000..0fd778435c
--- /dev/null
+++ b/common/logging/src/main/resources/error-codes/cordapp-duplicate-cordapps-installed.properties
@@ -0,0 +1,4 @@
+errorTemplate = The CorDapp (name: {0}, file: {1}) is installed multiple times on the node. The following files correspond to the exact same content: {2}
+shortDescription = A CorDapp has been installed multiple times on the same node.
+actionsToFix = Investigate the logs to determine the files with duplicate content, and remove one of them from the cordapps directory.
+aliases = iw8d4e
\ No newline at end of file
diff --git a/common/logging/src/main/resources/error-codes/cordapp-duplicate-cordapps-installed_en_US.properties b/common/logging/src/main/resources/error-codes/cordapp-duplicate-cordapps-installed_en_US.properties
new file mode 100644
index 0000000000..2354427df3
--- /dev/null
+++ b/common/logging/src/main/resources/error-codes/cordapp-duplicate-cordapps-installed_en_US.properties
@@ -0,0 +1,3 @@
+errorTemplate = The CorDapp (name: {0}, file: {1}) is installed multiple times on the node. The following files correspond to the exact same content: {2}
+shortDescription = A CorDapp has been installed multiple times on the same node.
+actionsToFix = Investigate the logs to determine the files with duplicate content, and remove one of them from the cordapps directory.
\ No newline at end of file
diff --git a/common/logging/src/main/resources/error-codes/cordapp-invalid-version-identifier.properties b/common/logging/src/main/resources/error-codes/cordapp-invalid-version-identifier.properties
new file mode 100644
index 0000000000..0922f80bb4
--- /dev/null
+++ b/common/logging/src/main/resources/error-codes/cordapp-invalid-version-identifier.properties
@@ -0,0 +1,4 @@
+errorTemplate = Version identifier ({0}) for attribute {1} must be a whole number starting from 1.
+shortDescription = A version attribute was specified in the CorDapp manifest with an invalid value. The value must be a whole number, and it must be greater than or equal to 1.
+actionsToFix = Investigate the logs to find the invalid attribute, and change the attribute value to be valid (a whole number greater than or equal to 1).
+aliases =
\ No newline at end of file
diff --git a/common/logging/src/main/resources/error-codes/cordapp-invalid-version-identifier_en_US.properties b/common/logging/src/main/resources/error-codes/cordapp-invalid-version-identifier_en_US.properties
new file mode 100644
index 0000000000..0922f80bb4
--- /dev/null
+++ b/common/logging/src/main/resources/error-codes/cordapp-invalid-version-identifier_en_US.properties
@@ -0,0 +1,4 @@
+errorTemplate = Version identifier ({0}) for attribute {1} must be a whole number starting from 1.
+shortDescription = A version attribute was specified in the CorDapp manifest with an invalid value. The value must be a whole number, and it must be greater than or equal to 1.
+actionsToFix = Investigate the logs to find the invalid attribute, and change the attribute value to be valid (a whole number greater than or equal to 1).
+aliases =
\ No newline at end of file
diff --git a/common/logging/src/main/resources/error-codes/cordapp-missing-version-attribute.properties b/common/logging/src/main/resources/error-codes/cordapp-missing-version-attribute.properties
new file mode 100644
index 0000000000..772b459195
--- /dev/null
+++ b/common/logging/src/main/resources/error-codes/cordapp-missing-version-attribute.properties
@@ -0,0 +1,4 @@
+errorTemplate = Target versionId attribute {0} not specified. Please specify a whole number starting from 1.
+shortDescription = A required version attribute was not specified in the manifest of the CorDapp JAR.
+actionsToFix = Investigate the logs to find out which version attribute has not been specified, and add that version attribute to the CorDapp manifest.
+aliases =
\ No newline at end of file
diff --git a/common/logging/src/main/resources/error-codes/cordapp-missing-version-attribute_en_US.properties b/common/logging/src/main/resources/error-codes/cordapp-missing-version-attribute_en_US.properties
new file mode 100644
index 0000000000..d8a7ab050a
--- /dev/null
+++ b/common/logging/src/main/resources/error-codes/cordapp-missing-version-attribute_en_US.properties
@@ -0,0 +1,3 @@
+errorTemplate = Target versionId attribute {0} not specified. Please specify a whole number starting from 1.
+shortDescription = A required version attribute was not specified in the manifest of the CorDapp JAR.
+actionsToFix = Investigate the logs to find out which version attribute has not been specified, and add that version attribute to the CorDapp manifest.
\ No newline at end of file
diff --git a/common/logging/src/main/resources/error-codes/cordapp-multiple-cordapps-for-flow.properties b/common/logging/src/main/resources/error-codes/cordapp-multiple-cordapps-for-flow.properties
new file mode 100644
index 0000000000..b1ebfb6bb4
--- /dev/null
+++ b/common/logging/src/main/resources/error-codes/cordapp-multiple-cordapps-for-flow.properties
@@ -0,0 +1,4 @@
+errorTemplate = There are multiple CorDapp JARs on the classpath for the flow {0}: [{1}]
+shortDescription = Multiple CorDapp JARs on the classpath define the same flow class. As a result, the platform will not know which version of the flow to start when the flow is invoked.
+actionsToFix = Investigate the logs to find out which CorDapp JARs define the same flow classes. The developers of these apps will need to resolve the clash.
+aliases =
\ No newline at end of file
diff --git a/common/logging/src/main/resources/error-codes/cordapp-multiple-cordapps-for-flow_en_US.properties b/common/logging/src/main/resources/error-codes/cordapp-multiple-cordapps-for-flow_en_US.properties
new file mode 100644
index 0000000000..b1ebfb6bb4
--- /dev/null
+++ b/common/logging/src/main/resources/error-codes/cordapp-multiple-cordapps-for-flow_en_US.properties
@@ -0,0 +1,4 @@
+errorTemplate = There are multiple CorDapp JARs on the classpath for the flow {0}: [{1}]
+shortDescription = Multiple CorDapp JARs on the classpath define the same flow class. As a result, the platform will not know which version of the flow to start when the flow is invoked.
+actionsToFix = Investigate the logs to find out which CorDapp JARs define the same flow classes. The developers of these apps will need to resolve the clash.
+aliases =
\ No newline at end of file
diff --git a/common/logging/src/test/kotlin/net/corda/commmon/logging/errorReporting/CordappErrorsTest.kt b/common/logging/src/test/kotlin/net/corda/commmon/logging/errorReporting/CordappErrorsTest.kt
new file mode 100644
index 0000000000..4e28410c78
--- /dev/null
+++ b/common/logging/src/test/kotlin/net/corda/commmon/logging/errorReporting/CordappErrorsTest.kt
@@ -0,0 +1,12 @@
+package net.corda.commmon.logging.errorReporting
+
+import net.corda.common.logging.errorReporting.CordappErrors
+
+class CordappErrorsTest : ErrorCodeTest<CordappErrors>(CordappErrors::class.java, true) {
+    override val dataForCodes = mapOf(
+            CordappErrors.MISSING_VERSION_ATTRIBUTE to listOf("test-attribute"),
+            CordappErrors.INVALID_VERSION_IDENTIFIER to listOf(-1, "test-attribute"),
+            CordappErrors.MULTIPLE_CORDAPPS_FOR_FLOW to listOf("MyTestFlow", "Jar 1, Jar 2"),
+            CordappErrors.DUPLICATE_CORDAPPS_INSTALLED to listOf("TestCordapp", "testapp.jar", "testapp2.jar")
+    )
+}
\ No newline at end of file
diff --git a/common/logging/src/test/kotlin/net/corda/commmon/logging/errorReporting/DatabaseErrorsTest.kt b/common/logging/src/test/kotlin/net/corda/commmon/logging/errorReporting/DatabaseErrorsTest.kt
new file mode 100644
index 0000000000..d8697e9415
--- /dev/null
+++ b/common/logging/src/test/kotlin/net/corda/commmon/logging/errorReporting/DatabaseErrorsTest.kt
@@ -0,0 +1,13 @@
+package net.corda.commmon.logging.errorReporting
+
+import net.corda.common.logging.errorReporting.NodeDatabaseErrors
+import java.net.InetAddress
+
+class DatabaseErrorsTest : ErrorCodeTest<NodeDatabaseErrors>(NodeDatabaseErrors::class.java) {
+    override val dataForCodes = mapOf(
+            NodeDatabaseErrors.COULD_NOT_CONNECT to listOf<Any>(),
+            NodeDatabaseErrors.FAILED_STARTUP to listOf(),
+            NodeDatabaseErrors.MISSING_DRIVER to listOf(),
+            NodeDatabaseErrors.PASSWORD_REQUIRED_FOR_H2 to listOf(InetAddress.getLocalHost())
+    )
+}
\ No newline at end of file
diff --git a/common/logging/src/test/kotlin/net/corda/commmon/logging/errorReporting/ErrorCodeTest.kt b/common/logging/src/test/kotlin/net/corda/commmon/logging/errorReporting/ErrorCodeTest.kt
new file mode 100644
index 0000000000..1faf5deaef
--- /dev/null
+++ b/common/logging/src/test/kotlin/net/corda/commmon/logging/errorReporting/ErrorCodeTest.kt
@@ -0,0 +1,61 @@
+package net.corda.commmon.logging.errorReporting
+
+import junit.framework.TestCase.assertFalse
+import net.corda.common.logging.errorReporting.ErrorCode
+import net.corda.common.logging.errorReporting.ErrorCodes
+import net.corda.common.logging.errorReporting.ErrorResource
+import net.corda.common.logging.errorReporting.ResourceBundleProperties
+import org.junit.Test
+import java.util.*
+import kotlin.test.assertTrue
+
+/**
+ * Utility for testing that error code resource files behave as expected.
+ *
+ * This allows for testing that error messages are printed correctly if they are provided the correct parameters. The test will fail if any
+ * of the parameters of the template are not filled in.
+ *
+ * To use, override the `dataForCodes` with a map from an error code enum value to a list of parameters the message template takes. If any
+ * are missed, the test will fail.
+ *
+ * `printProperties`, if set to true, will print the properties out the resource files, with the error message filled in. This allows the
+ * message to be inspected.
+ */
+abstract class ErrorCodeTest<T>(private val clazz: Class<T>,
+                                private val printProperties: Boolean = false) where T: Enum<T>, T: ErrorCodes {
+
+    abstract val dataForCodes: Map<T, List<Any>>
+
+    private class TestError<T>(override val code: T,
+                               override val parameters: List<Any>) : ErrorCode<T> where T: Enum<T>, T: ErrorCodes
+
+    @Test(timeout = 300_000)
+    fun `test error codes`() {
+        for ((code, params) in dataForCodes) {
+            val error = TestError(code, params)
+            val resource = ErrorResource.fromErrorCode(error, "error-codes", Locale.forLanguageTag("en-US"))
+            val message = resource.getErrorMessage(error.parameters.toTypedArray())
+            assertFalse(
+                    "The error message reported for code $code contains missing parameters",
+                    message.contains("\\{.*}".toRegex())
+            )
+            val otherProperties = Triple(resource.shortDescription, resource.actionsToFix, resource.aliases)
+            if (printProperties) {
+                println("Data for $code")
+                println("Error Message = $message")
+                println("${ResourceBundleProperties.SHORT_DESCRIPTION} = ${otherProperties.first}")
+                println("${ResourceBundleProperties.ACTIONS_TO_FIX} = ${otherProperties.second}")
+                println("${ResourceBundleProperties.ALIASES} = ${otherProperties.third}")
+                println("")
+            }
+        }
+    }
+
+    @Test(timeout = 300_000)
+    fun `ensure all error codes tested`() {
+        val expected = clazz.enumConstants.toSet()
+        val actual = dataForCodes.keys.toSet()
+        val missing = expected - actual
+        assertTrue(missing.isEmpty(), "The following codes have not been tested: $missing")
+    }
+}
\ No newline at end of file
diff --git a/node/src/main/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoader.kt b/node/src/main/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoader.kt
index a8fef21fc4..b134c69815 100644
--- a/node/src/main/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoader.kt
+++ b/node/src/main/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoader.kt
@@ -2,6 +2,10 @@ package net.corda.node.internal.cordapp
 
 import io.github.classgraph.ClassGraph
 import io.github.classgraph.ScanResult
+import net.corda.common.logging.errorReporting.CordappErrors
+import net.corda.common.logging.errorReporting.ErrorCode
+import net.corda.common.logging.errorReporting.NodeDatabaseErrors
+import net.corda.common.logging.errorReporting.NodeNamespaces
 import net.corda.core.cordapp.Cordapp
 import net.corda.core.crypto.SecureHash
 import net.corda.core.crypto.sha256
@@ -144,9 +148,7 @@ class JarScanningCordappLoader private constructor(private val cordappJarPaths:
             val duplicateCordapps = registeredCordapps.filter { it.jarHash == cordapp.jarHash }.toSet()
 
             if (duplicateCordapps.isNotEmpty()) {
-                throw IllegalStateException("The CorDapp (name: ${cordapp.info.shortName}, file: ${cordapp.name}) " +
-                        "is installed multiple times on the node. The following files correspond to the exact same content: " +
-                        "${duplicateCordapps.map { it.name }}")
+                throw DuplicateCordappsInstalledException(cordapp, duplicateCordapps)
             }
             if (registeredClassName in contractClasses) {
                 throw IllegalStateException("More than one CorDapp installed on the node for contract $registeredClassName. " +
@@ -227,12 +229,21 @@ class JarScanningCordappLoader private constructor(private val cordappJarPaths:
 
     private fun parseVersion(versionStr: String?, attributeName: String): Int {
         if (versionStr == null) {
-            throw CordappInvalidVersionException("Target versionId attribute $attributeName not specified. Please specify a whole number starting from 1.")
+            throw CordappInvalidVersionException(
+                    "Target versionId attribute $attributeName not specified. Please specify a whole number starting from 1.",
+                    CordappErrors.MISSING_VERSION_ATTRIBUTE,
+                    listOf(attributeName))
         }
         val version = versionStr.toIntOrNull()
-                ?: throw CordappInvalidVersionException("Version identifier ($versionStr) for attribute $attributeName must be a whole number starting from 1.")
+                ?: throw CordappInvalidVersionException(
+                        "Version identifier ($versionStr) for attribute $attributeName must be a whole number starting from 1.",
+                        CordappErrors.INVALID_VERSION_IDENTIFIER,
+                        listOf(versionStr, attributeName))
         if (version < 1) {
-            throw CordappInvalidVersionException("Target versionId ($versionStr) for attribute $attributeName must not be smaller than 1.")
+            throw CordappInvalidVersionException(
+                    "Target versionId ($versionStr) for attribute $attributeName must not be smaller than 1.",
+                    CordappErrors.INVALID_VERSION_IDENTIFIER,
+                    listOf(versionStr, attributeName))
         }
         return version
     }
@@ -403,12 +414,34 @@ class JarScanningCordappLoader private constructor(private val cordappJarPaths:
 /**
  * Thrown when scanning CorDapps.
  */
-class MultipleCordappsForFlowException(message: String) : Exception(message)
+class MultipleCordappsForFlowException(
+        message: String,
+        flowName: String,
+        jars: String
+) : Exception(message), ErrorCode<CordappErrors> {
+    override val code = CordappErrors.MULTIPLE_CORDAPPS_FOR_FLOW
+    override val parameters = listOf(flowName, jars)
+}
 
 /**
  * Thrown if an exception occurs whilst parsing version identifiers within cordapp configuration
  */
-class CordappInvalidVersionException(msg: String) : Exception(msg)
+class CordappInvalidVersionException(
+        msg: String,
+        override val code: CordappErrors,
+        override val parameters: List<Any> = listOf()
+) : Exception(msg), ErrorCode<CordappErrors>
+
+/**
+ * Thrown if duplicate CorDapps are installed on the node
+ */
+class DuplicateCordappsInstalledException(app: Cordapp, duplicates: Set<Cordapp>)
+    : IllegalStateException("The CorDapp (name: ${app.info.shortName}, file: ${app.name}) " +
+        "is installed multiple times on the node. The following files correspond to the exact same content: " +
+        "${duplicates.map { it.name }}"), ErrorCode<CordappErrors> {
+    override val code = CordappErrors.DUPLICATE_CORDAPPS_INSTALLED
+    override val parameters = listOf(app.info.shortName, app.name, duplicates.map { it.name })
+}
 
 abstract class CordappLoaderTemplate : CordappLoader {
 
@@ -436,7 +469,9 @@ abstract class CordappLoaderTemplate : CordappLoader {
                             }
                         }
                         throw MultipleCordappsForFlowException("There are multiple CorDapp JARs on the classpath for flow " +
-                                "${entry.value.first().first.name}: [ ${entry.value.joinToString { it.second.jarPath.toString() }} ].")
+                                "${entry.value.first().first.name}: [ ${entry.value.joinToString { it.second.jarPath.toString() }} ].",
+                                entry.value.first().first.name,
+                                entry.value.joinToString { it.second.jarPath.toString() })
                     }
                     entry.value.single().second
                 }
diff --git a/node/src/test/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoaderTest.kt b/node/src/test/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoaderTest.kt
index fa98ff7e59..0d3f8d8f54 100644
--- a/node/src/test/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoaderTest.kt
+++ b/node/src/test/kotlin/net/corda/node/internal/cordapp/JarScanningCordappLoaderTest.kt
@@ -1,6 +1,7 @@
 package net.corda.node.internal.cordapp
 
 import co.paralleluniverse.fibers.Suspendable
+import net.corda.common.logging.errorReporting.CordappErrors
 import net.corda.core.flows.*
 import net.corda.node.VersionInfo
 import net.corda.nodeapi.internal.DEV_PUB_KEY_HASHES
diff --git a/settings.gradle b/settings.gradle
index f3ec7e75d8..d582cee14e 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -108,5 +108,5 @@ include 'serialization-deterministic'
 
 include 'tools:checkpoint-agent'
 include 'detekt-plugins'
-include 'tools:error-page-builder'
+include 'tools:error-tool'
 
diff --git a/tools/error-page-builder/build.gradle b/tools/error-tool/build.gradle
similarity index 67%
rename from tools/error-page-builder/build.gradle
rename to tools/error-tool/build.gradle
index ed16c572b3..d1e11ec376 100644
--- a/tools/error-page-builder/build.gradle
+++ b/tools/error-tool/build.gradle
@@ -1,6 +1,3 @@
-group 'net.corda'
-version '4.5-SNAPSHOT'
-
 apply plugin: 'kotlin'
 apply plugin: 'com.github.johnrengelman.shadow'
 
@@ -12,9 +9,9 @@ dependencies {
     implementation project(":common-logging")
     implementation project(":tools:cliutils")
     implementation "info.picocli:picocli:$picocli_version"
-    testCompile group: 'junit', name: 'junit', version: '4.12'
-
     implementation "org.apache.logging.log4j:log4j-slf4j-impl:$log4j_version"
+
+    testCompile "junit:junit:4.12"
 }
 
 jar {
@@ -23,10 +20,12 @@ jar {
 }
 
 shadowJar {
-    baseName = "corda-tools-error-page-builder"
+    baseName = "corda-tools-error-utils"
     manifest {
         attributes(
-                'Main-Class': "net.corda.errorPageBuilder.ErrorPageBuilderKt"
+                'Main-Class': "net.corda.errorUtilities.ErrorToolKt"
         )
     }
-}
\ No newline at end of file
+}
+
+assemble.dependsOn shadowJar
\ No newline at end of file
diff --git a/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorResourceUtilities.kt b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorResourceUtilities.kt
new file mode 100644
index 0000000000..bcb88f6180
--- /dev/null
+++ b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorResourceUtilities.kt
@@ -0,0 +1,45 @@
+package net.corda.errorUtilities
+
+import java.net.URLClassLoader
+import java.nio.file.Path
+
+/**
+ * A class for reading and processing error code resource bundles from a given directory.
+ */
+class ErrorResourceUtilities {
+
+    companion object {
+        private val ERROR_INFO_RESOURCE_REGEX= ".*ErrorInfo.*".toRegex()
+        private val DEFAULT_RESOURCE_FILE_REGEX = "[^_]*\\.properties".toRegex()
+        private val PROPERTIES_FILE_REGEX = ".*\\.properties".toRegex()
+
+        /**
+         * List all resource bundle names in a given directory
+         */
+        fun listResourceNames(location: Path) : List<String> {
+            return location.toFile().walkTopDown().filter {
+                it.name.matches(DEFAULT_RESOURCE_FILE_REGEX) && !it.name.matches(ERROR_INFO_RESOURCE_REGEX)
+            }.map {
+                it.nameWithoutExtension
+            }.toList()
+        }
+
+        /**
+         * List all resource files in a given directory
+         */
+        fun listResourceFiles(location: Path) : List<String> {
+            return location.toFile().walkTopDown().filter {
+                it.name.matches(PROPERTIES_FILE_REGEX)
+            }.map { it.name }.toList()
+        }
+
+        /**
+         * Create a classloader with all URLs in a given directory
+         */
+        fun loaderFromDirectory(location: Path) : URLClassLoader {
+            val urls = arrayOf(location.toUri().toURL())
+            val sysLoader = ClassLoader.getSystemClassLoader()
+            return URLClassLoader(urls, sysLoader)
+        }
+    }
+}
\ No newline at end of file
diff --git a/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorTool.kt b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorTool.kt
new file mode 100644
index 0000000000..1c2f620c76
--- /dev/null
+++ b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorTool.kt
@@ -0,0 +1,29 @@
+package net.corda.errorUtilities
+
+import net.corda.cliutils.CordaCliWrapper
+import net.corda.cliutils.ExitCodes
+import net.corda.cliutils.start
+import net.corda.errorUtilities.docsTable.DocsTableCLI
+import net.corda.errorUtilities.resourceGenerator.ResourceGeneratorCLI
+
+fun main(args: Array<String>) = ErrorTool().start(args)
+
+
+/**
+ * Entry point for the error utilities.
+ *
+ * By itself, this doesn't do anything - instead one of the subcommands should be invoked.
+ */
+class ErrorTool : CordaCliWrapper("error-utils", "Utilities for working with error codes and error reporting") {
+
+    private val errorPageBuilder = DocsTableCLI()
+    private val errorResourceGenerator = ResourceGeneratorCLI()
+
+    override fun additionalSubCommands() = setOf(errorPageBuilder, errorResourceGenerator)
+
+    override fun runProgram(): Int {
+        println("No subcommand specified - please invoke one of the subcommands.")
+        printHelp()
+        return ExitCodes.FAILURE
+    }
+}
\ No newline at end of file
diff --git a/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorToolCLIUtilities.kt b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorToolCLIUtilities.kt
new file mode 100644
index 0000000000..b76c655b68
--- /dev/null
+++ b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorToolCLIUtilities.kt
@@ -0,0 +1,23 @@
+package net.corda.errorUtilities
+
+import java.lang.IllegalArgumentException
+import java.nio.file.Files
+import java.nio.file.Path
+
+/**
+ * Common functions to use among multiple of the error code subcommands
+ */
+class ErrorToolCLIUtilities {
+    companion object {
+        /**
+         * Checks that a directory provided through Picocli exists.
+         */
+        fun checkDirectory(dir: Path?, expectedContents: String) : Path {
+            return dir?.also {
+                require(Files.exists(it)) {
+                    "Directory $it does not exist. Please specify a valid direction for $expectedContents"
+                }
+            } ?: throw IllegalArgumentException("No location specified for $expectedContents. Please specify a directory for $expectedContents.")
+        }
+    }
+}
\ No newline at end of file
diff --git a/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorToolExceptions.kt b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorToolExceptions.kt
new file mode 100644
index 0000000000..070316493b
--- /dev/null
+++ b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/ErrorToolExceptions.kt
@@ -0,0 +1,7 @@
+package net.corda.errorUtilities
+
+abstract class ErrorToolException(msg: String, cause: Exception? = null) : Exception(msg, cause)
+
+class ClassDoesNotExistException(classname: String)
+    : ErrorToolException("The class $classname could not be found in the provided JAR. " +
+        "Check that the correct fully qualified name has been provided and the JAR file is the correct one for this class.")
\ No newline at end of file
diff --git a/tools/error-page-builder/src/main/kotlin/net/corda/errorPageBuilder/ErrorPageBuilder.kt b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/docsTable/DocsTableCLI.kt
similarity index 57%
rename from tools/error-page-builder/src/main/kotlin/net/corda/errorPageBuilder/ErrorPageBuilder.kt
rename to tools/error-tool/src/main/kotlin/net/corda/errorUtilities/docsTable/DocsTableCLI.kt
index abe122310d..7773be6ff7 100644
--- a/tools/error-page-builder/src/main/kotlin/net/corda/errorPageBuilder/ErrorPageBuilder.kt
+++ b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/docsTable/DocsTableCLI.kt
@@ -1,22 +1,24 @@
-package net.corda.errorPageBuilder
+package net.corda.errorUtilities.docsTable
 
 import net.corda.cliutils.CordaCliWrapper
 import net.corda.cliutils.ExitCodes
-import net.corda.cliutils.start
+import net.corda.errorUtilities.ErrorToolCLIUtilities
 import org.slf4j.LoggerFactory
 import picocli.CommandLine
-import java.io.File
 import java.lang.IllegalArgumentException
 import java.nio.file.Files
 import java.nio.file.Path
 import java.util.*
 
-fun main(args: Array<String>) {
-    val builder = ErrorPageBuilder()
-    builder.start(args)
-}
-
-class ErrorPageBuilder : CordaCliWrapper("error-page-builder", "Builds the error table for the error codes page") {
+/**
+ * Error tool sub-command for generating the documentation for error codes.
+ *
+ * The command needs a location to output the documentation to and a directory containing the resource files. From this, it generates a
+ * Markdown table with all defined error codes.
+ *
+ * In the event that the file already exists, the tool will report an error and exit.
+ */
+class DocsTableCLI : CordaCliWrapper("build-docs", "Builds the error table for the error codes page") {
 
     @CommandLine.Parameters(
             index = "0",
@@ -42,43 +44,27 @@ class ErrorPageBuilder : CordaCliWrapper("error-page-builder", "Builds the error
     var localeTag: String? = null
 
     companion object {
-        private val logger = LoggerFactory.getLogger(ErrorPageBuilder::class.java)
+        private val logger = LoggerFactory.getLogger(DocsTableCLI::class.java)
         private const val ERROR_CODES_FILE = "error-codes.md"
     }
 
-    private fun getOutputFile() : File {
-        return outputDir?.let {
-            require(Files.exists(it)) {
-                "Directory $it does not exist. Please specify a valid directory to write output to."
-            }
-            val outputPath = it.resolve(ERROR_CODES_FILE)
-            require(Files.notExists(outputPath)) {
-                "Output file $outputPath exists, please remove it and run again."
-            }
-            outputPath.toFile()
-        } ?: throw IllegalArgumentException("Directory not specified. Please specify a valid directory to write output to.")
-    }
-
-    private fun getResourceDir() : Path {
-        return resourceLocation?.also {
-            require(Files.exists(it)) {
-                "Resource location $it does not exist. Please specify a valid location for error code resources"
-            }
-        } ?: throw IllegalArgumentException("Resource location not specified. Please specify a resource location.")
-    }
-
     override fun runProgram(): Int {
         val locale = if (localeTag != null) Locale.forLanguageTag(localeTag) else Locale.getDefault()
         val (outputFile, resources) = try {
-            Pair(getOutputFile(), getResourceDir())
+            val output = ErrorToolCLIUtilities.checkDirectory(outputDir, "output file")
+            val outputPath = output.resolve(ERROR_CODES_FILE)
+            require(Files.notExists(outputPath)) {
+                "Output file $outputPath exists, please remove it and run again."
+            }
+            Pair(outputPath, ErrorToolCLIUtilities.checkDirectory(resourceLocation, "resource bundle files"))
         } catch (e: IllegalArgumentException) {
             logger.error(e.message, e)
             return ExitCodes.FAILURE
         }
-        val tableGenerator = ErrorTableGenerator(resources.toFile(), locale)
+        val tableGenerator = DocsTableGenerator(resources, locale)
         try {
             val table = tableGenerator.generateMarkdown()
-            outputFile.writeText(table)
+            outputFile.toFile().writeText(table)
         } catch (e: IllegalArgumentException) {
             logger.error(e.message, e)
             return ExitCodes.FAILURE
diff --git a/tools/error-page-builder/src/main/kotlin/net/corda/errorPageBuilder/ErrorTableGenerator.kt b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/docsTable/DocsTableGenerator.kt
similarity index 63%
rename from tools/error-page-builder/src/main/kotlin/net/corda/errorPageBuilder/ErrorTableGenerator.kt
rename to tools/error-tool/src/main/kotlin/net/corda/errorUtilities/docsTable/DocsTableGenerator.kt
index 6cf13436a2..d16675bf55 100644
--- a/tools/error-page-builder/src/main/kotlin/net/corda/errorPageBuilder/ErrorTableGenerator.kt
+++ b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/docsTable/DocsTableGenerator.kt
@@ -1,13 +1,16 @@
-package net.corda.errorPageBuilder
+package net.corda.errorUtilities.docsTable
 
 import net.corda.common.logging.errorReporting.ErrorResource
-import java.io.File
+import net.corda.errorUtilities.ErrorResourceUtilities
 import java.lang.IllegalArgumentException
-import java.net.URLClassLoader
+import java.nio.file.Path
 import java.util.*
 
-class ErrorTableGenerator(private val resourceLocation: File,
-                          private val locale: Locale) {
+/**
+ * Generate the documentation table given a resource file location set.
+ */
+class DocsTableGenerator(private val resourceLocation: Path,
+                         private val locale: Locale) {
 
     companion object {
         private const val ERROR_CODE_HEADING = "codeHeading"
@@ -15,7 +18,6 @@ class ErrorTableGenerator(private val resourceLocation: File,
         private const val DESCRIPTION_HEADING = "descriptionHeading"
         private const val TO_FIX_HEADING = "toFixHeading"
         private const val ERROR_HEADINGS_BUNDLE = "ErrorPageHeadings"
-        private const val ERROR_INFO_RESOURCE = "ErrorInfo.properties"
     }
 
     private fun getHeading(heading: String) : String {
@@ -23,23 +25,10 @@ class ErrorTableGenerator(private val resourceLocation: File,
         return resource.getString(heading)
     }
 
-    private fun listResources() : Iterator<String> {
-        return resourceLocation.walkTopDown().filter {
-            it.name.matches("[^_]*\\.properties".toRegex()) && !it.name.matches(ERROR_INFO_RESOURCE.toRegex())
-        }.map {
-            it.nameWithoutExtension
-        }.iterator()
-    }
-
-    private fun createLoader() : ClassLoader {
-        val urls = resourceLocation.walkTopDown().map { it.toURI().toURL() }.asIterable().toList().toTypedArray()
-        return URLClassLoader(urls)
-    }
-
     private fun generateTable() : List<List<String>> {
         val table = mutableListOf<List<String>>()
-        val loader = createLoader()
-        for (resource in listResources()) {
+        val loader = ErrorResourceUtilities.loaderFromDirectory(resourceLocation)
+        for (resource in ErrorResourceUtilities.listResourceNames(resourceLocation)) {
             val errorResource = ErrorResource.fromLoader(resource, loader, locale)
             table.add(listOf(resource, errorResource.aliases, errorResource.shortDescription, errorResource.actionsToFix))
         }
@@ -59,7 +48,7 @@ class ErrorTableGenerator(private val resourceLocation: File,
     }
 
     fun generateMarkdown() : String {
-        if (!resourceLocation.exists()) throw IllegalArgumentException("Directory $resourceLocation does not exist.")
+        if (!resourceLocation.toFile().exists()) throw IllegalArgumentException("Directory $resourceLocation does not exist.")
         val tableData = generateTable()
         return formatTable(tableData)
     }
diff --git a/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/resourceGenerator/ResourceGenerator.kt b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/resourceGenerator/ResourceGenerator.kt
new file mode 100644
index 0000000000..2cb34684dd
--- /dev/null
+++ b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/resourceGenerator/ResourceGenerator.kt
@@ -0,0 +1,79 @@
+package net.corda.errorUtilities.resourceGenerator
+
+import net.corda.common.logging.errorReporting.ErrorCodes
+import net.corda.common.logging.errorReporting.ResourceBundleProperties
+import net.corda.errorUtilities.ClassDoesNotExistException
+import java.nio.file.Path
+import java.util.*
+
+/**
+ * Generate a set of resource files from an enumeration of error codes.
+ */
+class ResourceGenerator(private val locales: List<Locale>) {
+
+    companion object {
+        internal const val MESSAGE_TEMPLATE_DEFAULT = "<Message template>"
+        internal const val SHORT_DESCRIPTION_DEFAULT = "<Short description>"
+        internal const val ACTIONS_TO_FIX_DEFAULT = "<Actions to fix>"
+        internal const val ALIASES_DEFAULT = ""
+    }
+
+    private fun createResourceFile(name: String, location: Path) {
+        val file = location.resolve(name)
+        val text = """
+            |${ResourceBundleProperties.MESSAGE_TEMPLATE} = $MESSAGE_TEMPLATE_DEFAULT
+            |${ResourceBundleProperties.SHORT_DESCRIPTION} = $SHORT_DESCRIPTION_DEFAULT
+            |${ResourceBundleProperties.ACTIONS_TO_FIX} = $ACTIONS_TO_FIX_DEFAULT
+            |${ResourceBundleProperties.ALIASES} = $ALIASES_DEFAULT
+        """.trimMargin()
+        file.toFile().writeText(text)
+    }
+
+    /**
+     * Create a set of resource files in the given location.
+     *
+     * @param resources The resource file names to create
+     * @param resourceLocation The location to create the resource files
+     */
+    fun createResources(resources: List<String>, resourceLocation: Path) {
+        for (resource in resources) {
+            createResourceFile(resource, resourceLocation)
+        }
+    }
+
+    private fun definedCodes(classes: List<String>, loader: ClassLoader) : List<String> {
+        return classes.flatMap {
+            val clazz = try {
+                loader.loadClass(it)
+            } catch (e: ClassNotFoundException) {
+                throw ClassDoesNotExistException(it)
+            }
+            if (ErrorCodes::class.java.isAssignableFrom(clazz) && clazz != ErrorCodes::class.java) {
+                val namespace = (clazz.enumConstants.first() as ErrorCodes).namespace.toLowerCase()
+                clazz.enumConstants.map { code -> "${namespace}-${code.toString().toLowerCase().replace("_", "-")}"}
+            } else {
+                listOf()
+            }
+        }
+    }
+
+    private fun getExpectedResources(codes: List<String>) : List<String> {
+        return codes.flatMap {
+            val localeResources = locales.map { locale -> "${it}_${locale.toLanguageTag().replace("-", "_")}.properties"}
+            localeResources + "$it.properties"
+        }
+    }
+
+    /**
+     * Calculate what resource files are missing from a set of resource files, given a set of error codes.
+     *
+     * @param classes The classes to generate resource files for
+     * @param resourceFiles The list of resource files
+     */
+    fun calculateMissingResources(classes: List<String>, resourceFiles: List<String>, loader: ClassLoader) : List<String> {
+        val codes = definedCodes(classes, loader)
+        val expected = getExpectedResources(codes)
+        val missing = expected - resourceFiles.toSet()
+        return missing.toList()
+    }
+}
\ No newline at end of file
diff --git a/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/resourceGenerator/ResourceGeneratorCLI.kt b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/resourceGenerator/ResourceGeneratorCLI.kt
new file mode 100644
index 0000000000..49b28f52ba
--- /dev/null
+++ b/tools/error-tool/src/main/kotlin/net/corda/errorUtilities/resourceGenerator/ResourceGeneratorCLI.kt
@@ -0,0 +1,75 @@
+package net.corda.errorUtilities.resourceGenerator
+
+import net.corda.cliutils.CordaCliWrapper
+import net.corda.cliutils.ExitCodes
+import net.corda.errorUtilities.ErrorResourceUtilities
+import net.corda.errorUtilities.ErrorToolCLIUtilities
+import org.slf4j.LoggerFactory
+import picocli.CommandLine
+import java.lang.IllegalArgumentException
+import java.nio.file.Path
+import java.util.*
+
+/**
+ * Subcommand for generating resource bundles from error codes.
+ *
+ * This subcommand takes a directory containing built class files that define the enumerations of codes, and a directory containing any
+ * existing resource bundles. From this, it generates any missing resource files with the properties specified. The data under these
+ * properties should then be filled in by hand.
+ */
+class ResourceGeneratorCLI : CordaCliWrapper(
+        "generate-resources",
+        "Generate any missing resource files for a set of error codes"
+) {
+
+    @CommandLine.Parameters(
+            index = "0",
+            paramLabel = "JAR_FILE",
+            arity = "1",
+            description = ["JAR file containing class files of the error code definitions"]
+    )
+    var jarFile: Path? = null
+
+    @CommandLine.Parameters(
+            index = "1",
+            paramLabel = "RESOURCE_DIR",
+            arity = "1",
+            description = ["Directory containing resource bundles for the error codes"]
+    )
+    var resourceDir: Path? = null
+
+    @CommandLine.Parameters(
+            index="2..*",
+            paramLabel = "ERROR_CODE_CLASSES",
+            description = ["Fully qualified class names of the error code classes to generate resources for"]
+    )
+    var classes: List<String> = mutableListOf()
+
+    @CommandLine.Option(
+            names = ["--locales"],
+            description = ["The set of locales to generate resource files for. Specified as locale tags, for example en-US"],
+            arity = "1"
+    )
+    var locales: List<String> = listOf("en-US")
+
+    companion object {
+        private val logger = LoggerFactory.getLogger(ResourceGeneratorCLI::class.java)
+    }
+
+    override fun runProgram(): Int {
+        val jarFileLocation = ErrorToolCLIUtilities.checkDirectory(jarFile, "error code definition class files")
+        val resourceLocation = ErrorToolCLIUtilities.checkDirectory(resourceDir, "resource bundle files")
+        val resourceGenerator = ResourceGenerator(locales.map { Locale.forLanguageTag(it) })
+        try {
+            val resources = ErrorResourceUtilities.listResourceFiles(resourceLocation)
+            val loader = ErrorResourceUtilities.loaderFromDirectory(jarFileLocation)
+            val missingResources = resourceGenerator.calculateMissingResources(classes, resources, loader)
+            resourceGenerator.createResources(missingResources, resourceLocation)
+            loader.close()
+        } catch (e: IllegalArgumentException) {
+            logger.error(e.message, e)
+            return ExitCodes.FAILURE
+        }
+        return ExitCodes.SUCCESS
+    }
+}
\ No newline at end of file
diff --git a/tools/error-page-builder/src/main/resources/ErrorPageHeadings.properties b/tools/error-tool/src/main/resources/ErrorPageHeadings.properties
similarity index 100%
rename from tools/error-page-builder/src/main/resources/ErrorPageHeadings.properties
rename to tools/error-tool/src/main/resources/ErrorPageHeadings.properties
diff --git a/tools/error-page-builder/src/main/resources/log4j2.xml b/tools/error-tool/src/main/resources/log4j2.xml
similarity index 100%
rename from tools/error-page-builder/src/main/resources/log4j2.xml
rename to tools/error-tool/src/main/resources/log4j2.xml
diff --git a/tools/error-page-builder/src/test/kotlin/ErrorTableGeneratorTest.kt b/tools/error-tool/src/test/kotlin/net/corda/errorUtilities/docsTable/DocsTableGeneratorTest.kt
similarity index 74%
rename from tools/error-page-builder/src/test/kotlin/ErrorTableGeneratorTest.kt
rename to tools/error-tool/src/test/kotlin/net/corda/errorUtilities/docsTable/DocsTableGeneratorTest.kt
index 211576dda1..59ca2ed17f 100644
--- a/tools/error-page-builder/src/test/kotlin/ErrorTableGeneratorTest.kt
+++ b/tools/error-tool/src/test/kotlin/net/corda/errorUtilities/docsTable/DocsTableGeneratorTest.kt
@@ -1,15 +1,15 @@
+package net.corda.errorUtilities.docsTable
+
 import junit.framework.TestCase.assertEquals
-import net.corda.errorPageBuilder.ErrorTableGenerator
 import org.junit.Test
-import java.io.File
 import java.lang.IllegalArgumentException
 import java.nio.file.Paths
 import java.util.*
 
-class ErrorTableGeneratorTest {
+class DocsTableGeneratorTest {
 
     companion object {
-        private val RESOURCE_LOCATION = Paths.get("src/test/resources/test-errors").toAbsolutePath().toFile()
+        private val RESOURCE_LOCATION = Paths.get("src/test/resources/test-errors").toAbsolutePath()
     }
 
     private val englishTable = """| Error Code | Aliases | Description | Actions to Fix |
@@ -22,24 +22,24 @@ class ErrorTableGeneratorTest {
         /| test-error | foo, bar | Teachtaireacht tástála | Roinnt gníomhartha |
     """.trimMargin("/")
 
-    @Test(timeout = 300_000)
+    @Test(timeout = 1000)
     fun `check error table is produced as expected`() {
-        val generator = ErrorTableGenerator(RESOURCE_LOCATION, Locale.forLanguageTag("en-US"))
+        val generator = DocsTableGenerator(RESOURCE_LOCATION, Locale.forLanguageTag("en-US"))
         val table = generator.generateMarkdown()
         // Raw strings in Kotlin always use Unix line endings, so this is required to keep the test passing on Windows
         assertEquals(englishTable.split("\n").joinToString(System.lineSeparator()), table)
     }
 
-    @Test(timeout = 300_000)
+    @Test(timeout = 1000)
     fun `check table in other locales is produced as expected`() {
-        val generator = ErrorTableGenerator(RESOURCE_LOCATION, Locale.forLanguageTag("ga-IE"))
+        val generator = DocsTableGenerator(RESOURCE_LOCATION, Locale.forLanguageTag("ga-IE"))
         val table = generator.generateMarkdown()
         assertEquals(irishTable.split("\n").joinToString(System.lineSeparator()), table)
     }
 
-    @Test(expected = IllegalArgumentException::class, timeout = 300_000)
+    @Test(expected = IllegalArgumentException::class, timeout = 1000)
     fun `error thrown if unknown directory passed to generator`() {
-        val generator = ErrorTableGenerator(File("not/a/directory"), Locale.getDefault())
+        val generator = DocsTableGenerator(Paths.get("not/a/directory"), Locale.getDefault())
         generator.generateMarkdown()
     }
 }
\ No newline at end of file
diff --git a/tools/error-tool/src/test/kotlin/net/corda/errorUtilities/resourceGenerator/ResourceGeneratorTest.kt b/tools/error-tool/src/test/kotlin/net/corda/errorUtilities/resourceGenerator/ResourceGeneratorTest.kt
new file mode 100644
index 0000000000..0e8b2be854
--- /dev/null
+++ b/tools/error-tool/src/test/kotlin/net/corda/errorUtilities/resourceGenerator/ResourceGeneratorTest.kt
@@ -0,0 +1,56 @@
+package net.corda.errorUtilities.resourceGenerator
+
+import junit.framework.TestCase.assertEquals
+import net.corda.common.logging.errorReporting.ResourceBundleProperties
+import org.junit.Test
+import java.util.*
+
+class ResourceGeneratorTest {
+
+    private val classes = listOf(TestCodes1::class.qualifiedName!!, TestCodes2::class.qualifiedName!!)
+
+    private fun expectedCodes() : List<String> {
+        val codes1 = TestCodes1.values().map { "${it.namespace.toLowerCase()}-${it.name.replace("_", "-").toLowerCase()}" }
+        val codes2 = TestCodes2.values().map { "${it.namespace.toLowerCase()}-${it.name.replace("_", "-").toLowerCase()}" }
+        return codes1 + codes2
+    }
+
+    @Test(timeout = 1000)
+    fun `no codes marked as missing if all resources are present`() {
+        val resourceGenerator = ResourceGenerator(listOf())
+        val currentFiles = expectedCodes().map { "$it.properties" }
+        val missing = resourceGenerator.calculateMissingResources(classes, currentFiles, TestCodes1::class.java.classLoader)
+        assertEquals(setOf<String>(), missing.toSet())
+    }
+
+    @Test(timeout = 1000)
+    fun `missing locales are marked as missing when other locales are present`() {
+        val resourceGenerator = ResourceGenerator(listOf("en-US", "ga-IE").map { Locale.forLanguageTag(it) })
+        val currentFiles = expectedCodes().flatMap { listOf("$it.properties", "${it}_en_US.properties") }
+        val missing = resourceGenerator.calculateMissingResources(classes, currentFiles, TestCodes1::class.java.classLoader)
+        assertEquals(expectedCodes().map { "${it}_ga_IE.properties" }.toSet(), missing.toSet())
+    }
+
+    @Test(timeout = 1000)
+    fun `test writing out files works correctly`() {
+        // First test that if all files are missing then the resource generator detects this
+        val resourceGenerator = ResourceGenerator(listOf())
+        val currentFiles = listOf<String>()
+        val missing = resourceGenerator.calculateMissingResources(classes, currentFiles, TestCodes1::class.java.classLoader)
+        assertEquals(expectedCodes().map { "$it.properties" }.toSet(), missing.toSet())
+
+        // Now check that all resource files that should be created are
+        val tempDir = createTempDir()
+        resourceGenerator.createResources(missing, tempDir.toPath())
+        val createdFiles = tempDir.walkTopDown().filter { it.isFile && it.extension == "properties" }.map { it.name }.toList()
+        assertEquals(missing, createdFiles)
+
+        // Now check that a created file has the expected properties and values
+        val properties = Properties()
+        properties.load(tempDir.walk().filter { it.isFile && it.extension == "properties"}.first().inputStream())
+        assertEquals(ResourceGenerator.SHORT_DESCRIPTION_DEFAULT, properties.getProperty(ResourceBundleProperties.SHORT_DESCRIPTION))
+        assertEquals(ResourceGenerator.ACTIONS_TO_FIX_DEFAULT, properties.getProperty(ResourceBundleProperties.ACTIONS_TO_FIX))
+        assertEquals(ResourceGenerator.MESSAGE_TEMPLATE_DEFAULT, properties.getProperty(ResourceBundleProperties.MESSAGE_TEMPLATE))
+        assertEquals(ResourceGenerator.ALIASES_DEFAULT, properties.getProperty(ResourceBundleProperties.ALIASES))
+    }
+}
\ No newline at end of file
diff --git a/tools/error-tool/src/test/kotlin/net/corda/errorUtilities/resourceGenerator/TestErrorCodes.kt b/tools/error-tool/src/test/kotlin/net/corda/errorUtilities/resourceGenerator/TestErrorCodes.kt
new file mode 100644
index 0000000000..0e33357797
--- /dev/null
+++ b/tools/error-tool/src/test/kotlin/net/corda/errorUtilities/resourceGenerator/TestErrorCodes.kt
@@ -0,0 +1,23 @@
+package net.corda.errorUtilities.resourceGenerator
+
+import net.corda.common.logging.errorReporting.ErrorCodes
+
+// These test errors are not used directly, but their compiled class files are used to verify the resource generator functionality.
+enum class TestNamespaces {
+    TN1,
+    TN2
+}
+
+enum class TestCodes1 : ErrorCodes {
+    CASE1,
+    CASE2;
+
+    override val namespace = TestNamespaces.TN1.toString()
+}
+
+enum class TestCodes2 : ErrorCodes {
+    CASE1,
+    CASE3;
+
+    override val namespace = TestNamespaces.TN2.toString()
+}
\ No newline at end of file
diff --git a/tools/error-page-builder/src/test/resources/ErrorPageHeadings.properties b/tools/error-tool/src/test/resources/ErrorPageHeadings.properties
similarity index 100%
rename from tools/error-page-builder/src/test/resources/ErrorPageHeadings.properties
rename to tools/error-tool/src/test/resources/ErrorPageHeadings.properties
diff --git a/tools/error-page-builder/src/test/resources/ErrorPageHeadings_ga_IE.properties b/tools/error-tool/src/test/resources/ErrorPageHeadings_ga_IE.properties
similarity index 100%
rename from tools/error-page-builder/src/test/resources/ErrorPageHeadings_ga_IE.properties
rename to tools/error-tool/src/test/resources/ErrorPageHeadings_ga_IE.properties
diff --git a/tools/error-page-builder/src/test/resources/test-errors/test-error.properties b/tools/error-tool/src/test/resources/test-errors/test-error.properties
similarity index 100%
rename from tools/error-page-builder/src/test/resources/test-errors/test-error.properties
rename to tools/error-tool/src/test/resources/test-errors/test-error.properties
diff --git a/tools/error-page-builder/src/test/resources/test-errors/test-error_ga_IE.properties b/tools/error-tool/src/test/resources/test-errors/test-error_ga_IE.properties
similarity index 100%
rename from tools/error-page-builder/src/test/resources/test-errors/test-error_ga_IE.properties
rename to tools/error-tool/src/test/resources/test-errors/test-error_ga_IE.properties