fix: parser doesn't validate against options parameter if the value is provided through an env var

src/parser/parse.ts

@@ -181,9 +181,7 @@ export class Parser<T extends ParserInput, TFlags extends OutputFlags<T['flags']
         flags[token.flag] = await flag.parse(flags[token.flag], this.context)
       } else {
         const input = token.input
-        if (flag.options && !flag.options.includes(input)) {
-          throw new m.errors.FlagInvalidOptionError(flag, input)
-        }
+        this._validateOptions(flag, input)
 
         // eslint-disable-next-line no-await-in-loop
         const value = flag.parse ? await flag.parse(input, this.context) : input
@@ -201,8 +199,12 @@ export class Parser<T extends ParserInput, TFlags extends OutputFlags<T['flags']
       if (flags[k]) continue
       if (flag.type === 'option' && flag.env) {
         const input = process.env[flag.env]
-        // eslint-disable-next-line no-await-in-loop
-        if (input) flags[k] = await flag.parse(input, this.context)
+        if (input) {
+          this._validateOptions(flag, input)
+
+          // eslint-disable-next-line no-await-in-loop
+          flags[k] = await flag.parse(input, this.context)
+        }
       }
 
       if (!(k in flags) && flag.default !== undefined) {
@@ -216,6 +218,11 @@ export class Parser<T extends ParserInput, TFlags extends OutputFlags<T['flags']
     return flags
   }
 
+  private _validateOptions(flag: OptionFlag<any>, input: string) {
+    if (flag.options && !flag.options.includes(input))
+      throw new m.errors.FlagInvalidOptionError(flag, input)
+  }
+
   private async _argv(): Promise<any[]> {
     const args: any[] = []
     const tokens = this._argTokens

test/parser/parse.test.ts

@@ -790,6 +790,28 @@ See more help with --help`)
 
       expect(message).to.equal('Expected --foo=invalidopt to be one of: myopt, myotheropt\nSee more help with --help')
     })
+    it('fails when invalid env var', async () => {
+      let message = ''
+      process.env.TEST_FOO = 'invalidopt'
+      try {
+        await parse([], {
+          flags: {foo: flags.string({options: ['myopt', 'myotheropt'], env: 'TEST_FOO'})},
+        })
+      } catch (error: any) {
+        message = error.message
+      }
+
+      expect(message).to.equal('Expected --foo=invalidopt to be one of: myopt, myotheropt\nSee more help with --help')
+    })
+
+    it('accepts valid option env var', async () => {
+      process.env.TEST_FOO = 'myopt'
+
+      const out = await parse([], {
+        flags: {foo: flags.string({options: ['myopt', 'myotheropt'], env: 'TEST_FOO'})},
+      })
+      expect(out.flags.foo).to.equal('myopt')
+    })
   })
 
   describe('url flag', () => {