diff --git a/packages/hoppscotch-app/components/http/Request.vue b/packages/hoppscotch-app/components/http/Request.vue
index f4b3b14cc..31c9c6f01 100644
--- a/packages/hoppscotch-app/components/http/Request.vue
+++ b/packages/hoppscotch-app/components/http/Request.vue
@@ -232,6 +232,7 @@
 
 <script setup lang="ts">
 import { computed, ref, useContext, watch } from "@nuxtjs/composition-api"
+import { isRight } from "fp-ts/lib/Either"
 import {
   updateRESTResponse,
   restEndpoint$,
@@ -303,25 +304,30 @@ watch(loading, () => {
   }
 })
 
-const newSendRequest = () => {
+const newSendRequest = async () => {
   loading.value = true
 
-  subscribeToStream(
-    runRESTRequest$(),
-    (responseState) => {
-      if (loading.value) {
-        // Check exists because, loading can be set to false
-        // when cancelled
-        updateRESTResponse(responseState)
+  const streamResult = await runRESTRequest$()
+
+  // TODO: What if stream fetching failed (script execution errors ?) (isLeft)
+  if (isRight(streamResult)) {
+    subscribeToStream(
+      streamResult.right,
+      (responseState) => {
+        if (loading.value) {
+          // Check exists because, loading can be set to false
+          // when cancelled
+          updateRESTResponse(responseState)
+        }
+      },
+      () => {
+        loading.value = false
+      },
+      () => {
+        loading.value = false
       }
-    },
-    () => {
-      loading.value = false
-    },
-    () => {
-      loading.value = false
-    }
-  )
+    )
+  }
 }
 
 const cancelRequest = () => {
diff --git a/packages/hoppscotch-app/helpers/RequestRunner.ts b/packages/hoppscotch-app/helpers/RequestRunner.ts
index 1b7019fb6..d4450c8ed 100644
--- a/packages/hoppscotch-app/helpers/RequestRunner.ts
+++ b/packages/hoppscotch-app/helpers/RequestRunner.ts
@@ -1,155 +1,80 @@
 import { Observable } from "rxjs"
 import { filter } from "rxjs/operators"
-import getEnvironmentVariablesFromScript from "./preRequest"
+import { chain, right, TaskEither } from "fp-ts/lib/TaskEither"
+import { pipe } from "fp-ts/lib/function"
+import { runTestScript, TestDescriptor } from "@hoppscotch/js-sandbox"
+import { isRight } from "fp-ts/lib/Either"
+import { getFinalEnvsFromPreRequest } from "./preRequest"
 import { getEffectiveRESTRequest } from "./utils/EffectiveURL"
 import { HoppRESTResponse } from "./types/HoppRESTResponse"
 import { createRESTNetworkRequestStream } from "./network"
-import runTestScriptWithVariables, {
-  transformResponseForTesting,
-} from "./postwomanTesting"
 import { HoppTestData, HoppTestResult } from "./types/HoppTestResult"
+import { isJSONContentType } from "./utils/contenttypes"
 import { getRESTRequest, setRESTTestResults } from "~/newstore/RESTSession"
 
-/**
- * Runs a REST network request along with all the
- * other side processes (like running test scripts)
- */
-export function runRESTRequest$(): Observable<HoppRESTResponse> {
-  const envs = getEnvironmentVariablesFromScript(
-    getRESTRequest().preRequestScript
+const getTestableBody = (res: HoppRESTResponse & { type: "success" }) => {
+  const contentTypeHeader = res.headers.find(
+    (h) => h.value.toLowerCase() === "content-type"
   )
 
-  const effectiveRequest = getEffectiveRESTRequest(getRESTRequest(), {
-    name: "Env",
-    variables: Object.keys(envs).map((key) => {
-      return {
-        key,
-        value: envs[key],
-      }
-    }),
-  })
+  const rawBody = new TextDecoder("utf-8").decode(res.body)
 
-  const stream = createRESTNetworkRequestStream(effectiveRequest)
+  if (!contentTypeHeader || !isJSONContentType(contentTypeHeader.value))
+    return rawBody
 
-  // Run Test Script when request ran successfully
-  const subscription = stream
-    .pipe(filter((res) => res.type === "success"))
-    .subscribe((res) => {
-      const testReport: {
-        report: "" // ¯\_(ツ)_/¯
-        testResults: Array<
-          | {
-              result: "FAIL"
-              message: string
-              styles: { icon: "close"; class: "cl-error-response" }
-            }
-          | {
-              result: "PASS"
-              message: string
-              styles: { icon: "check"; class: "success-response" }
-            }
-          | { startBlock: string; styles: { icon: ""; class: "" } }
-          | { endBlock: true; styles: { icon: ""; class: "" } }
-        >
-        errors: [] // ¯\_(ツ)_/¯
-      } = runTestScriptWithVariables(effectiveRequest.testScript, {
-        response: transformResponseForTesting(res),
-      }) as any
+  return JSON.parse(rawBody)
+}
 
-      setRESTTestResults(translateToNewTestResults(testReport))
-
-      subscription.unsubscribe()
+export const runRESTRequest$: TaskEither<
+  string,
+  Observable<HoppRESTResponse>
+> = pipe(
+  getFinalEnvsFromPreRequest(),
+  chain((envs) => {
+    console.log(envs)
+    const effectiveRequest = getEffectiveRESTRequest(getRESTRequest(), {
+      name: "Env",
+      variables: envs,
     })
 
-  return stream
-}
+    const stream = createRESTNetworkRequestStream(effectiveRequest)
 
-function isTestPass(x: any): x is {
-  result: "PASS"
-  styles: { icon: "check"; class: "success-response" }
-} {
-  return x.result !== undefined && x.result === "PASS"
-}
+    // Run Test Script when request ran successfully
+    const subscription = stream
+      .pipe(filter((res) => res.type === "success"))
+      .subscribe(async (res) => {
+        if (res.type === "success") {
+          const runResult = await runTestScript(res.req.testScript, {
+            status: res.statusCode,
+            body: getTestableBody(res),
+            headers: res.headers,
+          })()
 
-function isTestFail(x: any): x is {
-  result: "FAIL"
-  message: string
-  styles: { icon: "close"; class: "cl-error-response" }
-} {
-  return x.result !== undefined && x.result === "FAIL"
-}
+          // TODO: Handle script executation fails (isLeft)
+          if (isRight(runResult)) {
+            setRESTTestResults(translateToSandboxTestResults(runResult.right))
+          }
 
-function isStartBlock(
-  x: any
-): x is { startBlock: string; styles: { icon: ""; class: "" } } {
-  return x.startBlock !== undefined
-}
-
-function isEndBlock(
-  x: any
-): x is { endBlock: true; styles: { icon: ""; class: "" } } {
-  return x.endBlock !== undefined
-}
-
-function translateToNewTestResults(testReport: {
-  report: "" // ¯\_(ツ)_/¯
-  testResults: Array<
-    | {
-        result: "FAIL"
-        message: string
-        styles: { icon: "close"; class: "cl-error-response" }
-      }
-    | {
-        result: "PASS"
-        message: string
-        styles: { icon: "check"; class: "success-response" }
-      }
-    | { startBlock: string; styles: { icon: ""; class: "" } }
-    | { endBlock: true; styles: { icon: ""; class: "" } }
-  >
-  errors: [] // ¯\_(ツ)_/¯
-}): HoppTestResult {
-  // Build a stack of test data which we eventually build up based on the results
-  const testsStack: HoppTestData[] = [
-    {
-      description: "root",
-      tests: [],
-      expectResults: [],
-    },
-  ]
-
-  testReport.testResults.forEach((result) => {
-    // This is a test block start, push an empty test to the stack
-    if (isStartBlock(result)) {
-      testsStack.push({
-        description: result.startBlock,
-        tests: [],
-        expectResults: [],
+          subscription.unsubscribe()
+        }
       })
-    } else if (isEndBlock(result)) {
-      // End of the block, pop the stack and add it as a child to the current stack top
-      const testData = testsStack.pop()!
-      testsStack[testsStack.length - 1].tests.push(testData)
-    } else if (isTestPass(result)) {
-      // A normal PASS expectation
-      testsStack[testsStack.length - 1].expectResults.push({
-        status: "pass",
-        message: result.message,
-      })
-    } else if (isTestFail(result)) {
-      // A normal FAIL expectation
-      testsStack[testsStack.length - 1].expectResults.push({
-        status: "fail",
-        message: result.message,
-      })
-    }
+
+    return right(stream)
   })
+)
 
-  // We should end up with only the root stack entry
-  if (testsStack.length !== 1) throw new Error("Invalid test result structure")
-
+function translateToSandboxTestResults(
+  testDesc: TestDescriptor
+): HoppTestResult {
+  const translateChildTests = (child: TestDescriptor): HoppTestData => {
+    return {
+      description: child.descriptor,
+      expectResults: child.expectResults,
+      tests: child.children.map(translateChildTests),
+    }
+  }
   return {
-    expectResults: testsStack[0].expectResults,
-    tests: testsStack[0].tests,
+    expectResults: testDesc.expectResults,
+    tests: testDesc.children.map(translateChildTests),
   }
 }
diff --git a/packages/hoppscotch-app/helpers/postwomanTesting.ts b/packages/hoppscotch-app/helpers/postwomanTesting.ts
deleted file mode 100644
index 4057e905a..000000000
--- a/packages/hoppscotch-app/helpers/postwomanTesting.ts
+++ /dev/null
@@ -1,321 +0,0 @@
-import { HoppRESTResponse } from "./types/HoppRESTResponse"
-
-const styles = {
-  PASS: { icon: "check", class: "success-response" },
-  FAIL: { icon: "close", class: "cl-error-response" },
-  ERROR: { icon: "close", class: "cl-error-response" },
-}
-
-type TestScriptResponse = {
-  body: any
-  headers: any[]
-  status: number
-
-  __newRes: HoppRESTResponse
-}
-
-type TestScriptVariables = {
-  response: TestScriptResponse
-}
-
-type TestReportStartBlock = {
-  startBlock: string
-}
-
-type TestReportEndBlock = {
-  endBlock: true
-}
-
-type TestReportEntry = {
-  result: "PASS" | "FAIL" | "ERROR"
-  message: string
-  styles: {
-    icon: string
-  }
-}
-
-type TestReport = TestReportStartBlock | TestReportEntry | TestReportEndBlock
-
-export default function runTestScriptWithVariables(
-  script: string,
-  variables?: TestScriptVariables
-) {
-  const pw = {
-    _errors: [],
-    _testReports: [] as TestReport[],
-    _report: "",
-    expect(value: any) {
-      try {
-        return expect(value, this._testReports)
-      } catch (e: any) {
-        pw._testReports.push({
-          result: "ERROR",
-          message: `${e}`,
-          styles: styles.ERROR,
-        })
-      }
-    },
-    test: (descriptor: string, func: () => void) =>
-      test(descriptor, func, pw._testReports),
-    // globals that the script is allowed to have access to.
-  }
-  Object.assign(pw, variables)
-
-  // run pre-request script within this function so that it has access to the pw object.
-  // eslint-disable-next-line no-new-func
-  new Function("pw", script)(pw)
-
-  return {
-    report: pw._report,
-    errors: pw._errors,
-    testResults: pw._testReports,
-  }
-}
-
-function test(
-  descriptor: string,
-  func: () => void,
-  _testReports: TestReport[]
-) {
-  _testReports.push({ startBlock: descriptor })
-  try {
-    func()
-  } catch (e: any) {
-    _testReports.push({ result: "ERROR", message: e, styles: styles.ERROR })
-  }
-  _testReports.push({ endBlock: true })
-
-  // TODO: Organize and generate text report of each {descriptor: true} section in testReports.
-  // add checkmark or x depending on if each testReport is pass=true or pass=false
-}
-
-function expect(expectValue: any, _testReports: TestReport[]) {
-  return new Expectation(expectValue, null, _testReports)
-}
-
-class Expectation {
-  private expectValue: any
-  private not: true | Expectation
-  private _testReports: TestReport[]
-
-  constructor(
-    expectValue: any,
-    _not: boolean | null,
-    _testReports: TestReport[]
-  ) {
-    this.expectValue = expectValue
-    this.not = _not || new Expectation(this.expectValue, true, _testReports)
-    this._testReports = _testReports // this values is used within Test.it, which wraps Expectation and passes _testReports value.
-  }
-
-  private _satisfies(expectValue: any, targetValue?: any): boolean {
-    // Used for testing if two values match the expectation, which could be === OR !==, depending on if not
-    // was used. Expectation#_satisfies prevents the need to have an if(this.not) branch in every test method.
-    // Signature is _satisfies([expectValue,] targetValue): if only one argument is given, it is assumed the targetValue, and expectValue is set to this.expectValue
-    if (!targetValue) {
-      targetValue = expectValue
-      expectValue = this.expectValue
-    }
-    if (this.not === true) {
-      // test the inverse. this.not is always truthly, but an Expectation that is inverted will always be strictly `true`
-      return expectValue !== targetValue
-    } else {
-      return expectValue === targetValue
-    }
-  }
-
-  _fmtNot(message: string) {
-    // given a string with "(not)" in it, replaces with "not" or "", depending if the expectation is expecting the positive or inverse (this._not)
-    if (this.not === true) {
-      return message.replace("(not)", "not ")
-    } else {
-      return message.replace("(not)", "")
-    }
-  }
-
-  _fail(message: string) {
-    return this._testReports.push({
-      result: "FAIL",
-      message,
-      styles: styles.FAIL,
-    })
-  }
-
-  _pass(message: string) {
-    return this._testReports.push({
-      result: "PASS",
-      message,
-      styles: styles.PASS,
-    })
-  }
-
-  // TEST METHODS DEFINED BELOW
-  // these are the usual methods that would follow expect(...)
-  toBe(value: any) {
-    return this._satisfies(value)
-      ? this._pass(
-          this._fmtNot(`${this.expectValue} do (not)match with ${value}`)
-        )
-      : this._fail(
-          this._fmtNot(`Expected ${this.expectValue} (not)to be ${value}`)
-        )
-  }
-
-  toHaveProperty(value: string) {
-    return this._satisfies(
-      Object.prototype.hasOwnProperty.call(this.expectValue, value),
-      true
-    )
-      ? this._pass(
-          this._fmtNot(`${this.expectValue} do (not)have property ${value}`)
-        )
-      : this._fail(
-          this._fmtNot(
-            `Expected object ${this.expectValue} to (not)have property ${value}`
-          )
-        )
-  }
-
-  toBeLevel2xx() {
-    const code = parseInt(this.expectValue, 10)
-    if (Number.isNaN(code)) {
-      return this._fail(
-        `Expected 200-level status but could not parse value ${this.expectValue}`
-      )
-    }
-    return this._satisfies(code >= 200 && code < 300, true)
-      ? this._pass(
-          this._fmtNot(`${this.expectValue} is (not)a 200-level status`)
-        )
-      : this._fail(
-          this._fmtNot(
-            `Expected ${this.expectValue} to (not)be 200-level status`
-          )
-        )
-  }
-
-  toBeLevel3xx() {
-    const code = parseInt(this.expectValue, 10)
-    if (Number.isNaN(code)) {
-      return this._fail(
-        `Expected 300-level status but could not parse value ${this.expectValue}`
-      )
-    }
-    return this._satisfies(code >= 300 && code < 400, true)
-      ? this._pass(
-          this._fmtNot(`${this.expectValue} is (not)a 300-level status`)
-        )
-      : this._fail(
-          this._fmtNot(
-            `Expected ${this.expectValue} to (not)be 300-level status`
-          )
-        )
-  }
-
-  toBeLevel4xx() {
-    const code = parseInt(this.expectValue, 10)
-    if (Number.isNaN(code)) {
-      return this._fail(
-        `Expected 400-level status but could not parse value ${this.expectValue}`
-      )
-    }
-    return this._satisfies(code >= 400 && code < 500, true)
-      ? this._pass(
-          this._fmtNot(`${this.expectValue} is (not)a 400-level status`)
-        )
-      : this._fail(
-          this._fmtNot(
-            `Expected ${this.expectValue} to (not)be 400-level status`
-          )
-        )
-  }
-
-  toBeLevel5xx() {
-    const code = parseInt(this.expectValue, 10)
-    if (Number.isNaN(code)) {
-      return this._fail(
-        `Expected 500-level status but could not parse value ${this.expectValue}`
-      )
-    }
-    return this._satisfies(code >= 500 && code < 600, true)
-      ? this._pass(
-          this._fmtNot(`${this.expectValue} is (not)a 500-level status`)
-        )
-      : this._fail(
-          this._fmtNot(
-            `Expected ${this.expectValue} to (not)be 500-level status`
-          )
-        )
-  }
-
-  toHaveLength(expectedLength: number) {
-    const actualLength = this.expectValue.length
-    return this._satisfies(actualLength, expectedLength)
-      ? this._pass(
-          this._fmtNot(
-            `Length expectation of (not)being ${expectedLength} is kept`
-          )
-        )
-      : this._fail(
-          this._fmtNot(
-            `Expected length to be ${expectedLength} but actual length was ${actualLength}`
-          )
-        )
-  }
-
-  toBeType(expectedType: string) {
-    const actualType = typeof this.expectValue
-    if (
-      ![
-        "string",
-        "boolean",
-        "number",
-        "object",
-        "undefined",
-        "bigint",
-        "symbol",
-        "function",
-      ].includes(expectedType)
-    ) {
-      return this._fail(
-        this._fmtNot(
-          `Argument for toBeType should be "string", "boolean", "number", "object", "undefined", "bigint", "symbol" or "function"`
-        )
-      )
-    }
-    return this._satisfies(actualType, expectedType)
-      ? this._pass(this._fmtNot(`The type is (not)"${expectedType}"`))
-      : this._fail(
-          this._fmtNot(
-            `Expected type to be "${expectedType}" but actual type was "${actualType}"`
-          )
-        )
-  }
-}
-
-export function transformResponseForTesting(
-  response: HoppRESTResponse
-): TestScriptResponse {
-  if (response.type === "loading") {
-    throw new Error("Cannot transform loading responses")
-  }
-
-  if (response.type === "network_fail") {
-    throw new Error("Cannot transform failed responses")
-  }
-
-  let body: any = new TextDecoder("utf-8").decode(response.body)
-
-  // Try parsing to JSON
-  try {
-    body = JSON.parse(body)
-  } catch (_) {}
-
-  return {
-    body,
-    headers: response.headers,
-    status: response.statusCode,
-
-    __newRes: response,
-  }
-}
diff --git a/packages/hoppscotch-app/helpers/preRequest.ts b/packages/hoppscotch-app/helpers/preRequest.ts
index 48ce28636..b5e53731b 100644
--- a/packages/hoppscotch-app/helpers/preRequest.ts
+++ b/packages/hoppscotch-app/helpers/preRequest.ts
@@ -1,42 +1,31 @@
+import { runPreRequestScript } from "@hoppscotch/js-sandbox"
 import {
   getCurrentEnvironment,
   getGlobalVariables,
 } from "~/newstore/environments"
+import { getRESTRequest } from "~/newstore/RESTSession"
 
-export default function getEnvironmentVariablesFromScript(script: string) {
-  const _variables: Record<string, string> = {}
+export const getCombinedEnvVariables = () => {
+  const variables: { key: string; value: string }[] = [...getGlobalVariables()]
 
-  const currentEnv = getCurrentEnvironment()
+  for (const variable of getCurrentEnvironment().variables) {
+    const index = variables.findIndex((v) => variable.key === v.key)
 
-  for (const variable of currentEnv.variables) {
-    _variables[variable.key] = variable.value
-  }
-
-  const globalEnv = getGlobalVariables()
-
-  if (globalEnv) {
-    for (const variable of globalEnv) {
-      _variables[variable.key] = variable.value
+    if (index === -1) {
+      variables.push({
+        key: variable.key,
+        value: variable.value,
+      })
+    } else {
+      variables[index].value = variable.value
     }
   }
 
-  try {
-    // the pw object is the proxy by which pre-request scripts can pass variables to the request.
-    // for security and control purposes, this is the only way a pre-request script should modify variables.
-    const pw = {
-      environment: {
-        set: (key: string, value: string) => (_variables[key] = value),
-      },
-      env: {
-        set: (key: string, value: string) => (_variables[key] = value),
-      },
-      // globals that the script is allowed to have access to.
-    }
-
-    // run pre-request script within this function so that it has access to the pw object.
-    // eslint-disable-next-line no-new-func
-    new Function("pw", script)(pw)
-  } catch (_e) {}
-
-  return _variables
+  return variables
 }
+
+export const getFinalEnvsFromPreRequest = () =>
+  runPreRequestScript(
+    getRESTRequest().preRequestScript,
+    getCombinedEnvVariables()
+  )