From 6e94b68598c7e0c8efe42d9243222a99a535ff0c Mon Sep 17 00:00:00 2001
From: Jerko Steiner <jerko.steiner@gmail.com>
Date: Tue, 22 Jan 2019 11:57:05 +0100
Subject: [PATCH] Add server/src/validator

---
 .../src/validator/IValidationMessage.ts       |  4 +
 .../server/src/validator/ValidationError.ts   | 17 ++++
 .../server/src/validator/Validator.test.ts    | 84 +++++++++++++++++++
 packages/server/src/validator/Validator.ts    | 48 +++++++++++
 packages/server/src/validator/index.ts        |  3 +
 5 files changed, 156 insertions(+)
 create mode 100644 packages/server/src/validator/IValidationMessage.ts
 create mode 100644 packages/server/src/validator/ValidationError.ts
 create mode 100644 packages/server/src/validator/Validator.test.ts
 create mode 100644 packages/server/src/validator/Validator.ts
 create mode 100644 packages/server/src/validator/index.ts

diff --git a/packages/server/src/validator/IValidationMessage.ts b/packages/server/src/validator/IValidationMessage.ts
new file mode 100644
index 0000000..6beb9e4
--- /dev/null
+++ b/packages/server/src/validator/IValidationMessage.ts
@@ -0,0 +1,4 @@
+export interface IValidationMessage {
+  readonly property: string | number | symbol
+  readonly message: string
+}
diff --git a/packages/server/src/validator/ValidationError.ts b/packages/server/src/validator/ValidationError.ts
new file mode 100644
index 0000000..27aab28
--- /dev/null
+++ b/packages/server/src/validator/ValidationError.ts
@@ -0,0 +1,17 @@
+import {IValidationMessage} from './IValidationMessage'
+
+export class ValidationError extends Error {
+  readonly name: string
+  constructor(
+    readonly errors: IValidationMessage[],
+    message?: string,
+  ) {
+    super(
+      message
+      ? message
+      : 'Validation failed on properties: ' +
+        errors.map(e => e.property).join(', '))
+    this.name = 'ValidationError'
+    Error.captureStackTrace(this)
+  }
+}
diff --git a/packages/server/src/validator/Validator.test.ts b/packages/server/src/validator/Validator.test.ts
new file mode 100644
index 0000000..72e0538
--- /dev/null
+++ b/packages/server/src/validator/Validator.test.ts
@@ -0,0 +1,84 @@
+import {Validator} from './Validator'
+
+describe('Validator', () => {
+
+  const entity = {
+    a: 0,
+    b: 1,
+    c: 2,
+    d: undefined,
+    e: false,
+    f: null,
+  }
+
+  let v!: Validator<typeof entity>
+  beforeEach(() => {
+    v = new Validator(entity)
+  })
+
+  describe('constructor', () => {
+    it('throws when an entity is not provided', () => {
+      expect(() => new Validator(undefined))
+      .toThrowError(/record could not be found/)
+    })
+  })
+
+  describe('ensure', () => {
+    it('adds an error when a value is falsy', () => {
+      v.ensure('a')
+      expect(v.errors.length).toBe(1)
+      v.ensure('e')
+      expect(v.errors.length).toBe(2)
+    })
+    it('adds an error when a value does not exist', () => {
+      v.ensure('b')
+      expect(v.errors.length).toBe(0)
+      v.ensure('b')
+      expect(v.errors.length).toBe(0)
+      v.ensure('c')
+      expect(v.errors.length).toBe(0)
+      v.ensure('d')
+      expect(v.errors.length).toBe(1)
+    })
+
+    it('adds an error when a value does not match', () => {
+      v.ensure('a', entity.a)
+      v.ensure('b', entity.b)
+      v.ensure('c', entity.c)
+      v.ensure('d', entity.d)
+      v.ensure('e', entity.e)
+      v.ensure('f', entity.f)
+      expect(v.errors.length).toBe(0)
+
+      v.ensure('f', undefined)
+      expect(v.errors.length).toBe(1)
+    })
+  })
+
+  describe('getError', () => {
+    it('returns undefined when no error', () => {
+      v.ensure('a', entity.a)
+      expect(v.getError()).toBe(undefined)
+    })
+    it('returns an error when a validation errors was encountered', () => {
+      v.ensure('a', 999)
+      const err = v.getError()!
+      expect(err).toBeTruthy()
+      expect(err.name).toEqual('ValidationError')
+      expect(err.message).toMatch(/Validation failed on properties/)
+    })
+  })
+
+  describe('throw', () => {
+    it('does nothing when no validation errors', () => {
+      v.ensure('a', entity.a)
+      v.throw()
+    })
+
+    it('throws when there are validation errors', () => {
+      v.ensure('a', 999)
+      expect(() => v.throw()).toThrowError()
+    })
+  })
+
+})
diff --git a/packages/server/src/validator/Validator.ts b/packages/server/src/validator/Validator.ts
new file mode 100644
index 0000000..afb106d
--- /dev/null
+++ b/packages/server/src/validator/Validator.ts
@@ -0,0 +1,48 @@
+import {IValidationMessage} from './IValidationMessage'
+import {ValidationError} from './ValidationError'
+
+export class Validator<T> {
+
+  readonly errors: IValidationMessage[] = []
+  readonly entity: T
+
+  constructor(entity: T | undefined) {
+    if (!entity) {
+      throw new ValidationError([], 'The record could not be found')
+    }
+    this.entity = entity
+  }
+
+  ensure(property: keyof T, value?: any): this {
+    if (arguments.length === 1) {
+      if (!this.entity[property]) {
+        this.addError(property, `The property "${property}" is invalid`)
+      }
+      return this
+    }
+
+    if (this.entity[property] !== value) {
+      this.addError(property,
+      `The property "${property}" should be equal to "${value}"` +
+      ` but the actual value is "${this.entity[property]}"`)
+    }
+    return this
+  }
+
+  getError(): ValidationError | undefined {
+    if (this.errors.length) {
+      return new ValidationError(this.errors)
+    }
+  }
+
+  throw() {
+    const error = this.getError()
+    if (error) {
+      throw error
+    }
+  }
+
+  protected addError(property: keyof T, message: string) {
+    this.errors.push({property, message})
+  }
+}
diff --git a/packages/server/src/validator/index.ts b/packages/server/src/validator/index.ts
new file mode 100644
index 0000000..31baf0f
--- /dev/null
+++ b/packages/server/src/validator/index.ts
@@ -0,0 +1,3 @@
+export * from './IValidationMessage'
+export * from './ValidationError'
+export * from './Validator'