use arbitrary for creating work

zebra-chain/src/work/difficulty.rs

@@ -123,9 +123,9 @@ impl fmt::Debug for ExpandedDifficulty {
 #[derive(Clone, Copy, Default, Eq, PartialEq, Ord, PartialOrd)]
 pub struct Work(u128);
 
-impl From<Work> for u128 {
-    fn from(work: Work) -> Self {
-        work.0
+impl Work {
+    pub fn as_u128(self) -> u128 {
+        self.0
     }
 }
 

zebra-chain/src/work/difficulty/arbitrary.rs

@@ -51,15 +51,7 @@ impl Arbitrary for Work {
         // In the Zcash protocol, a Work is converted from an ExpandedDifficulty.
         // But some randomised difficulties are impractically large, and will
         // never appear in any real-world block. So we just use a random Work value.
-        (any::<u128>())
-            .prop_filter_map("zero Work values are invalid", |w| {
-                if w == 0 {
-                    None
-                } else {
-                    Some(Work(w))
-                }
-            })
-            .boxed()
+        (1..std::u128::MAX).prop_map(Work).boxed()
     }
 
     type Strategy = BoxedStrategy<Self>;

zebra-state/src/tests.rs

@@ -84,11 +84,11 @@ use proptest::prelude::*;
 fn round_trip_work_expanded() {
     zebra_test::init();
 
-    proptest!(|(work in 1..std::u128::MAX)| {
-        let work: U256 = work.into();
+    proptest!(|(work in any::<Work>())| {
+        let work: U256 = work.as_u128().into();
         let expanded = work_to_expanded(work);
         let work_after = Work::try_from(expanded).unwrap();
-        let work_after = u128::from(work_after);
+        let work_after = work_after.as_u128();
         let work_after = U256::from(work_after);
         prop_assert_eq!(work, work_after);
     });