feat: Improve either error messages

Fix #9
charlespascoe · Jan 20, 2018 · 3a10582 · 3a10582
1 parent 2df6590
commit 3a10582
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Showing 3 changed files with 73 additions and 18 deletions.
diff --git a/lib/index.ts b/lib/index.ts
@@ -1,4 +1,4 @@
-import { keysOf, tryCatch, increaseIndent } from './utils';
+import { keysOf, tryCatch } from './utils';
 import {
   ArrayIndexPathNode,
   error,
@@ -9,6 +9,7 @@ import {
   success,
   ValidationError,
   ValidationResult,
+  EitherValidationError
 } from './validation-result';
 export * from './validation-result';
 
@@ -341,29 +342,54 @@ export function eachValue<T>(assertion: (arg: any) => ValidationResult<T>, next?
 }
 
 
-export function either<A,B>(assertion1: (arg: any) => ValidationResult<A>, assertion2: (arg: any) => ValidationResult<B>): (arg: any) => ValidationResult<A | B>;
-export function either<A,B,C>(assertion1: (arg: any) => ValidationResult<A>, assertion2: (arg: any) => ValidationResult<B>, assertion3: (arg: any) => ValidationResult<C>): (arg: any) => ValidationResult<A | B | C>;
-export function either<A,B,C,D>(assertion1: (arg: any) => ValidationResult<A>, assertion2: (arg: any) => ValidationResult<B>, assertion3: (arg: any) => ValidationResult<C>, assertion4: (arg: any) => ValidationResult<D>): (arg: any) => ValidationResult<A | B | C | D>;
-export function either<A,B,C,D,E>(assertion1: (arg: any) => ValidationResult<A>, assertion2: (arg: any) => ValidationResult<B>, assertion3: (arg: any) => ValidationResult<C>, assertion4: (arg: any) => ValidationResult<D>, assertion5: (arg: any) => ValidationResult<E>): (arg: any) => ValidationResult<A | B | C | D | E>;
-export function either<A,B,C,D,E,F>(assertion1: (arg: any) => ValidationResult<A>, assertion2: (arg: any) => ValidationResult<B>, assertion3: (arg: any) => ValidationResult<C>, assertion4: (arg: any) => ValidationResult<D>, assertion5: (arg: any) => ValidationResult<E>, assertion6: (arg: any) => ValidationResult<F>): (arg: any) => ValidationResult<A | B | C | D | E | F>;
-export function either<A,B,C,D,E,F,G>(assertion1: (arg: any) => ValidationResult<A>, assertion2: (arg: any) => ValidationResult<B>, assertion3: (arg: any) => ValidationResult<C>, assertion4: (arg: any) => ValidationResult<D>, assertion5: (arg: any) => ValidationResult<E>, assertion6: (arg: any) => ValidationResult<F>, assertion7: (arg: any) => ValidationResult<G>): (arg: any) => ValidationResult<A | B | C | D | E | F | G>;
-export function either<A,B,C,D,E,F,G,H>(assertion1: (arg: any) => ValidationResult<A>, assertion2: (arg: any) => ValidationResult<B>, assertion3: (arg: any) => ValidationResult<C>, assertion4: (arg: any) => ValidationResult<D>, assertion5: (arg: any) => ValidationResult<E>, assertion6: (arg: any) => ValidationResult<F>, assertion7: (arg: any) => ValidationResult<G>, assertion8: (arg: any) => ValidationResult<H>): (arg: any) => ValidationResult<A | B | C | D | E | F | G | H>;
-export function either<A,B,C,D,E,F,G,H,I>(assertion1: (arg: any) => ValidationResult<A>, assertion2: (arg: any) => ValidationResult<B>, assertion3: (arg: any) => ValidationResult<C>, assertion4: (arg: any) => ValidationResult<D>, assertion5: (arg: any) => ValidationResult<E>, assertion6: (arg: any) => ValidationResult<F>, assertion7: (arg: any) => ValidationResult<G>, assertion8: (arg: any) => ValidationResult<H>, assertion9: (arg: any) => ValidationResult<I>): (arg: any) => ValidationResult<A | B | C | D | E | F | G | H | I>;
-export function either<A,B,C,D,E,F,G,H,I,J>(assertion1: (arg: any) => ValidationResult<A>, assertion2: (arg: any) => ValidationResult<B>, assertion3: (arg: any) => ValidationResult<C>, assertion4: (arg: any) => ValidationResult<D>, assertion5: (arg: any) => ValidationResult<E>, assertion6: (arg: any) => ValidationResult<F>, assertion7: (arg: any) => ValidationResult<G>, assertion8: (arg: any) => ValidationResult<H>, assertion9: (arg: any) => ValidationResult<I>, assertion10: (arg: any) => ValidationResult<J>): (arg: any) => ValidationResult<A | B | C | D | E | F | G | H | I | J>;
-export function either(...assertions: Array<(arg: any) => any>): (arg: any) => any {
+export interface IEitherOption<T> {
+  description: string;
+  assertion: (arg: any) => ValidationResult<T>;
+}
+
+
+export function is<T>(description: string, assertion: (arg: any) => ValidationResult<T>): IEitherOption<T> {
+  return {description, assertion};
+}
+
+
+// These overloads are necessary for type safety
+export function either<A,B>(option1: IEitherOption<A>, option2: IEitherOption<B>): (arg: any) => ValidationResult<A|B>;
+export function either<A,B,C>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>): (arg: any) => ValidationResult<A|B|C>;
+export function either<A,B,C,D>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>): (arg: any) => ValidationResult<A|B|C|D>;
+export function either<A,B,C,D,E>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>): (arg: any) => ValidationResult<A|B|C|D|E>;
+export function either<A,B,C,D,E,F>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>): (arg: any) => ValidationResult<A|B|C|D|E|F>;
+export function either<A,B,C,D,E,F,G>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>): (arg: any) => ValidationResult<A|B|C|D|E|F|G>;
+export function either<A,B,C,D,E,F,G,H>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H>;
+export function either<A,B,C,D,E,F,G,H,I>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I>;
+export function either<A,B,C,D,E,F,G,H,I,J>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J>;
+export function either<A,B,C,D,E,F,G,H,I,J,K>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K>;
+export function either<A,B,C,D,E,F,G,H,I,J,K,L>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>, option12: IEitherOption<L>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K|L>;
+export function either<A,B,C,D,E,F,G,H,I,J,K,L,M>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>, option12: IEitherOption<L>, option13: IEitherOption<M>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K|L|M>;
+export function either<A,B,C,D,E,F,G,H,I,J,K,L,M,N>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>, option12: IEitherOption<L>, option13: IEitherOption<M>, option14: IEitherOption<N>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K|L|M|N>;
+export function either<A,B,C,D,E,F,G,H,I,J,K,L,M,N,O>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>, option12: IEitherOption<L>, option13: IEitherOption<M>, option14: IEitherOption<N>, option15: IEitherOption<O>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K|L|M|N|O>;
+export function either<A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>, option12: IEitherOption<L>, option13: IEitherOption<M>, option14: IEitherOption<N>, option15: IEitherOption<O>, option16: IEitherOption<P>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P>;
+export function either<A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>, option12: IEitherOption<L>, option13: IEitherOption<M>, option14: IEitherOption<N>, option15: IEitherOption<O>, option16: IEitherOption<P>, option17: IEitherOption<Q>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q>;
+export function either<A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>, option12: IEitherOption<L>, option13: IEitherOption<M>, option14: IEitherOption<N>, option15: IEitherOption<O>, option16: IEitherOption<P>, option17: IEitherOption<Q>, option18: IEitherOption<R>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R>;
+export function either<A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>, option12: IEitherOption<L>, option13: IEitherOption<M>, option14: IEitherOption<N>, option15: IEitherOption<O>, option16: IEitherOption<P>, option17: IEitherOption<Q>, option18: IEitherOption<R>, option19: IEitherOption<S>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S>;
+export function either<A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T>(option1: IEitherOption<A>, option2: IEitherOption<B>, option3: IEitherOption<C>, option4: IEitherOption<D>, option5: IEitherOption<E>, option6: IEitherOption<F>, option7: IEitherOption<G>, option8: IEitherOption<H>, option9: IEitherOption<I>, option10: IEitherOption<J>, option11: IEitherOption<K>, option12: IEitherOption<L>, option13: IEitherOption<M>, option14: IEitherOption<N>, option15: IEitherOption<O>, option16: IEitherOption<P>, option17: IEitherOption<Q>, option18: IEitherOption<R>, option19: IEitherOption<S>, option20: IEitherOption<T>): (arg: any) => ValidationResult<A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T>;
+export function either(...options: Array<IEitherOption<any>>): (arg: any) => any {
   return (arg: any) => {
-    let errors: ValidationError[] = [];
+    const eitherError = new EitherValidationError();
 
-    for (const assertion of assertions) {
-      const result = assertion(arg);
+    for (const option of options) {
+      const result = tryCatch(
+        () => option.assertion(arg),
+        (err) => errorFromException(err)
+      );
 
       if (result.success) {
         return result;
       }
 
-      errors = errors.concat(result.errors);
+      eitherError.errors[option.description] = result.errors;
     }
 
-    return error('NO_MATCH', 'No match found - the following assertions failed:\n' + errors.map(error => increaseIndent(error.toString(), 2)).join('\n'));
+    return new ErrorResult(eitherError);
   };
 }
diff --git a/lib/utils.ts b/lib/utils.ts
@@ -35,3 +35,8 @@ export function increaseIndent(text: string, indent: number): string {
   const indentPadding = repeat(' ', indent);
   return indentPadding + text.split('\n').join('\n' + indentPadding);
 }
+
+
+export function pluralise(count: number, singular: string, plural: string): string {
+  return `${count} ${count === 1 ? singular : plural}`;
+}
diff --git a/lib/validation-result.ts b/lib/validation-result.ts
@@ -1,4 +1,4 @@
-import { increaseIndent } from './utils';
+import { increaseIndent, keysOf, pluralise } from './utils';
 
 
 export type ValidationResult<T> = SuccessResult<T> | ErrorResult;
@@ -56,6 +56,30 @@ export class ValidationError {
 }
 
 
+export class EitherValidationError extends ValidationError {
+  public readonly errors: {[description: string]: ValidationError[]} = {};
+
+  constructor() {
+    super('NO_MATCH', 'No match found');
+  }
+
+  public toString(root: string = '$'): string {
+    return `${this.pathString(root)}: ${this.message} - the following assertions failed:\n` +
+      keysOf(this.errors)
+        .map(desc => {
+          const errors = this.errors[desc];
+
+          return increaseIndent(
+            `Not ${desc}, due to ${pluralise(errors.length, 'validation error', 'validation errors')}:\n` +
+              errors.map(error => increaseIndent(error.toString(), 4)).join('\n'),
+            4
+          );
+        })
+        .join('\n');
+  }
+}
+
+
 export class ErrorResult {
   public readonly success: false = false;
 
@@ -78,7 +102,7 @@ export class ErrorResult {
   }
 
   public toString(root: string = '$'): string {
-    return `${this.errors.length} validation error${this.errors.length === 1 ? '' : 's'}:\n${this.errors.map(error => increaseIndent(error.toString(root), 2)).join('\n')}`;
+    return `${this.errors.length} validation error${this.errors.length === 1 ? '' : 's'}:\n${this.errors.map(error => increaseIndent(error.toString(root), 4)).join('\n')}`;
   }
 
   public static isErrorResult(arg: any): arg is ErrorResult {