diff --git a/tools/src/helpers.ts b/tools/src/helpers.ts
index 4144afd3..d338f796 100644
--- a/tools/src/helpers.ts
+++ b/tools/src/helpers.ts
@@ -160,3 +160,21 @@ export function write_json (file_path: string, content: any, replacer?: (this: a
 export async function sleep (ms: number): Promise<void> {
   await new Promise<void>((resolve) => setTimeout(resolve, ms))
 }
+
+/**
+ * Returns a string split using a delimiter, but only up to a certain number of times,
+ * returning the remainder of the string as the last element if the result.
+ *
+ * @param str a string
+ * @param delim delimiter
+ * @param count max number of splits
+ * @returns an array of strings
+ */
+export function split(str: any, delim: string, count: number = 0): string[] {
+  if (str === undefined) return []
+  const parts = str.split(delim)
+  if (count <= 0 || parts.length <= count) return parts
+  const result = parts.slice(0, count - 1)
+  result.push(parts.slice(count - 1).join(delim))
+  return result
+}
diff --git a/tools/src/tester/OutputReference.ts b/tools/src/tester/OutputReference.ts
new file mode 100644
index 00000000..4c47212a
--- /dev/null
+++ b/tools/src/tester/OutputReference.ts
@@ -0,0 +1,57 @@
+/*
+* Copyright OpenSearch Contributors
+* SPDX-License-Identifier: Apache-2.0
+*
+* The OpenSearch Contributors require contributions made to
+* this file be licensed under the Apache-2.0 license or a
+* compatible open source license.
+*/
+
+import { split } from "helpers"
+
+export class OutputReference {
+  chapter_id: string
+  output_name: string|undefined
+
+  constructor(chapter_id: string, output_name: string | undefined = undefined) {
+    this.chapter_id = chapter_id
+    this.output_name = output_name
+  }
+
+  /**
+   * Parses a string and returns a collection of output references that it may contain.
+   *
+   * @param str a string
+   * @returns an array of output references
+   */
+  static parse(str: string): OutputReference[] {
+    const pattern = /\$\{([^}]+)\}/g
+    let match
+    var result = []
+    while ((match = pattern.exec(str)) !== null) {
+      const spl = split(match[1], '.', 2)
+      result.push(new OutputReference(spl[0], spl[1]))
+    }
+    return result
+  }
+
+  /**
+   * Replaces occurrences of output references.
+   * Takes special care of preserving the type of the reference value if the entire string is a reference.
+   *
+   * @param str a string that may contain output references
+   * @param callback a callback for fetching reference values
+   * @returns a string with output references replaced by their values
+   */
+  static replace(str: string, callback: (chapter_id: any, variable: any) => string): any {
+    let full_match = str.match(/^\$\{([^}]+)\}$/)
+    if (full_match) {
+      // the entire string is a reference, preserve the type of the returned value
+      const spl = split(full_match[1], '.', 2)
+      return callback(spl[0], spl[1])
+    } else return str.replace(/\$\{([^}]+)\}/g, (_, k) => {
+      const spl = split(k, '.', 2)
+      return callback(spl[0], spl[1])
+    })
+  }
+}
diff --git a/tools/src/tester/StoryEvaluator.ts b/tools/src/tester/StoryEvaluator.ts
index 839760dc..eb0bbf2f 100644
--- a/tools/src/tester/StoryEvaluator.ts
+++ b/tools/src/tester/StoryEvaluator.ts
@@ -8,7 +8,7 @@
 */
 
 import { ChapterRequest, Parameter, SupplementalChapter } from './types/story.types'
-import { type StoryFile, type ChapterEvaluation, Result, type StoryEvaluation, OutputReference } from './types/eval.types'
+import { type StoryFile, type ChapterEvaluation, Result, type StoryEvaluation } from './types/eval.types'
 import type ChapterEvaluator from './ChapterEvaluator'
 import { overall_result } from './helpers'
 import { StoryOutputs } from './StoryOutputs'
@@ -17,6 +17,7 @@ import { ChapterOutput } from './ChapterOutput'
 import * as semver from '../_utils/semver'
 import _ from 'lodash'
 import { ParsedChapter, ParsedStory } from './types/parsed_story.types'
+import { OutputReference } from './OutputReference'
 
 export default class StoryEvaluator {
   private readonly _chapter_evaluator: ChapterEvaluator
diff --git a/tools/src/tester/types/eval.types.ts b/tools/src/tester/types/eval.types.ts
index f29714af..0686a689 100644
--- a/tools/src/tester/types/eval.types.ts
+++ b/tools/src/tester/types/eval.types.ts
@@ -83,46 +83,3 @@ export enum Result {
   SKIPPED = 'SKIPPED',
   ERROR = 'ERROR',
 }
-
-export class OutputReference {
-  chapter_id: string
-  output_name: string
-
-  private constructor(chapter_id: string, output_name: string) {
-    this.chapter_id = chapter_id
-    this.output_name = output_name
-  }
-
-  static parse(str: string): OutputReference[] {
-    const pattern = /\$\{([^}]+)\}/g
-    let match
-    var result = []
-    while ((match = pattern.exec(str)) !== null) {
-      const spl = this.#split(match[1], '.', 2)
-      result.push(new OutputReference(spl[0], spl[1]))
-    }
-    return result
-  }
-
-  static replace(str: string, callback: (chapter_id: any, variable: any) => string): any {
-    // preserve type if 1 value is returned
-    let full_match = str.match(/^\$\{([^}]+)\}$/)
-    if (full_match) {
-      const spl = this.#split(full_match[1], '.', 2)
-      return callback(spl[0], spl[1])
-    } else return str.replace(/\$\{([^}]+)\}/g, (_, k) => {
-      const spl = this.#split(k, '.', 2)
-      return callback(spl[0], spl[1])
-    });
-  }
-
-  static #split(str: any, delim: string, count: number): string[] {
-    if (str === undefined) return [str]
-    if (count <= 0) return [str]
-    const parts = str.split(delim)
-    if (parts.length <= count) return parts
-    const result = parts.slice(0, count - 1)
-    result.push(parts.slice(count - 1).join(delim))
-    return result
-  }
-}
diff --git a/tools/tests/helpers.test.ts b/tools/tests/helpers.test.ts
index f91dde57..3e1f1547 100644
--- a/tools/tests/helpers.test.ts
+++ b/tools/tests/helpers.test.ts
@@ -8,7 +8,7 @@
 */
 
 import _ from 'lodash'
-import { delete_matching_keys, find_refs, sort_array_by_keys, to_json, to_ndjson } from '../src/helpers'
+import { delete_matching_keys, find_refs, sort_array_by_keys, to_json, to_ndjson, split } from '../src/helpers'
 
 describe('helpers', () => {
   describe('sort_array_by_keys', () => {
@@ -195,4 +195,27 @@ describe('helpers', () => {
       })).toEqual(new Set(['#1', '#2', '#3', '#dup', '#/schemas/schema1', '#/schemas/schema2']))
     })
   })
+
+  describe('split', () => {
+    test('undefined', () => {
+      expect(split(undefined, '.')).toEqual([])
+    })
+
+    test('one element', () => {
+      expect(split('str', '.')).toEqual(['str'])
+      expect(split('str', '.', -1)).toEqual(['str'])
+      expect(split('str', '.', 0)).toEqual(['str'])
+      expect(split('str', '.', 10)).toEqual(['str'])
+    })
+
+    test('multiple elements', () => {
+      expect(split('x.y.z', '.')).toEqual(['x', 'y', 'z'])
+      expect(split('x.y.z', '.', -1)).toEqual(['x', 'y', 'z'])
+      expect(split('x.y.z', '.', 0)).toEqual(['x', 'y', 'z'])
+      expect(split('x.y.z', '.', 1)).toEqual(['x.y.z'])
+      expect(split('x.y.z', '.', 2)).toEqual(['x', 'y.z'])
+      expect(split('x.y.z', '.', 3)).toEqual(['x', 'y', 'z'])
+      expect(split('x.y.z', '.', 4)).toEqual(['x', 'y', 'z'])
+    })
+  })
 })
diff --git a/tools/tests/tester/OutputReference.test.ts b/tools/tests/tester/OutputReference.test.ts
new file mode 100644
index 00000000..c5efdd0e
--- /dev/null
+++ b/tools/tests/tester/OutputReference.test.ts
@@ -0,0 +1,40 @@
+/*
+* Copyright OpenSearch Contributors
+* SPDX-License-Identifier: Apache-2.0
+*
+* The OpenSearch Contributors require contributions made to
+* this file be licensed under the Apache-2.0 license or a
+* compatible open source license.
+*/
+
+import { OutputReference } from "tester/OutputReference";
+
+describe('OutputReference', () => {
+  let f = (id: any, k: any): string => `[${id}:${k}]`
+
+  describe('parse', () => {
+    it('replaces', () => {
+      expect(OutputReference.parse('string')).toEqual([])
+      expect(OutputReference.parse('${k.v}')).toEqual([new OutputReference('k', 'v')])
+      expect(OutputReference.parse('${k.value}')).toEqual([new OutputReference('k', 'value')])
+      expect(OutputReference.parse('${k.v.m}')).toEqual([new OutputReference('k', 'v.m')])
+      expect(OutputReference.parse('A reference to ${k.v.m} and ${x} and ${x.y}.')).toEqual([
+        new OutputReference('k', 'v.m'),
+        new OutputReference('x'),
+        new OutputReference('x', 'y')
+      ])
+    })
+  })
+
+  describe('replace', () => {
+    it('replaces', () => {
+      expect(OutputReference.replace('string', f)).toEqual('string')
+      expect(OutputReference.replace('${k.v}', f)).toEqual('[k:v]')
+      expect(OutputReference.replace('${k.value}', f)).toEqual('[k:value]')
+      expect(OutputReference.replace('${k.v.m}', f)).toEqual('[k:v.m]')
+      expect(OutputReference.replace('A reference to ${k.v.m} and ${x} and ${x.y}.', f)).toEqual(
+        'A reference to [k:v.m] and [x:undefined] and [x:y].'
+      )
+    })
+  })
+});
diff --git a/tools/tests/types/eval.types.test.ts b/tools/tests/types/eval.types.test.ts
deleted file mode 100644
index 76f7f3ac..00000000
--- a/tools/tests/types/eval.types.test.ts
+++ /dev/null
@@ -1,23 +0,0 @@
-/*
-* Copyright OpenSearch Contributors
-* SPDX-License-Identifier: Apache-2.0
-*
-* The OpenSearch Contributors require contributions made to
-* this file be licensed under the Apache-2.0 license or a
-* compatible open source license.
-*/
-
-import { OutputReference } from "tester/types/eval.types";
-
-describe('OutputReference', () => {
-  let f = (id: any, k: any): string => `[${id}:${k}]`
-
-  describe('replace', () => {
-    it('replaces', () => {
-      expect(OutputReference.replace('string', f)).toEqual('string')
-      expect(OutputReference.replace('${k.v}', f)).toEqual('[k:v]')
-      expect(OutputReference.replace('${k.value}', f)).toEqual('[k:value]')
-      expect(OutputReference.replace('${k.v.m}', f)).toEqual('[k:v.m]')
-    })
-  })
-});