Fix Cause.pretty when toString is invalid (#2143)

Author: mikearnaldi

.changeset/honest-cameras-nail.md

@@ -0,0 +1,17 @@
+---
+"effect": patch
+---
+
+Fix Cause.pretty when toString is invalid
+
+```ts
+import { Cause } from "effect";
+
+console.log(Cause.pretty(Cause.fail([{ toString: "" }])));
+```
+
+The code above used to throw now it prints:
+
+```bash
+Error: [{"toString":""}]
+```

packages/effect/src/internal/cause.ts

@@ -1040,12 +1040,17 @@ export const prettyErrorMessage = (u: unknown): string => {
     return `Error: ${u}`
   }
   // 2)
-  if (
-    hasProperty(u, "toString") &&
-    isFunction(u["toString"]) &&
-    u["toString"] !== Object.prototype.toString
-  ) {
-    return u["toString"]()
+  try {
+    if (
+      hasProperty(u, "toString") &&
+      isFunction(u["toString"]) &&
+      u["toString"] !== Object.prototype.toString &&
+      u["toString"] !== Array.prototype.toString
+    ) {
+      return u["toString"]()
+    }
+  } catch {
+    // something's off, rollback to json
   }
   // 3)
   return `Error: ${JSON.stringify(u)}`

packages/effect/test/Cause.test.ts

@@ -354,4 +354,10 @@ describe("Cause", () => {
       }
     })
   })
+
+  describe("Pretty", () => {
+    it("doesn't blow up on array errors", () => {
+      assert.strictEqual(Cause.pretty(Cause.fail([{ toString: "" }])), `Error: [{"toString":""}]`)
+    })
+  })
 })

packages/schema/test/util.ts

@@ -79,26 +79,29 @@ const effectifyAST = (ast: AST.AST): AST.AST => {
 export const effectify = <A, I>(schema: S.Schema<A, I, never>): S.Schema<A, I, never> =>
   S.make(effectifyAST(schema.ast))
 
-export const roundtrip = <A, I>(schema: S.Schema<A, I, never>) => {
+export const roundtrip = <A, I>(schema: S.Schema<A, I, never>, params?: Parameters<typeof fc.assert>[1]) => {
   if (!doRoundtrip) {
     return
   }
   const arb = A.make(schema)
   const is = S.is(schema)
   const encode = S.encode(schema)
   const decode = S.decode(schema)
-  fc.assert(fc.property(arb(fc), (a) => {
-    const roundtrip = encode(a).pipe(
-      Effect.mapError(() => "encoding" as const),
-      Effect.flatMap((i) => decode(i).pipe(Effect.mapError(() => "decoding" as const))),
-      Effect.either,
-      Effect.runSync
-    )
-    if (Either.isLeft(roundtrip)) {
-      return roundtrip.left === "encoding"
-    }
-    return is(roundtrip.right)
-  }))
+  fc.assert(
+    fc.property(arb(fc), (a) => {
+      const roundtrip = encode(a).pipe(
+        Effect.mapError(() => "encoding" as const),
+        Effect.flatMap((i) => decode(i).pipe(Effect.mapError(() => "decoding" as const))),
+        Effect.either,
+        Effect.runSync
+      )
+      if (Either.isLeft(roundtrip)) {
+        return roundtrip.left === "encoding"
+      }
+      return is(roundtrip.right)
+    }),
+    params
+  )
   if (doEffectify) {
     const effectSchema = effectify(schema)
     const encode = S.encode(effectSchema)