Move work conversion helpers to test code

Cargo.lock

@@ -3478,6 +3478,7 @@ dependencies = [
  "lazy_static",
  "metrics",
  "once_cell",
+ "primitive-types",
  "proptest",
  "serde",
  "sled",

zebra-chain/src/work/difficulty.rs

@@ -260,39 +260,12 @@ impl TryFrom<ExpandedDifficulty> for Work {
     }
 }
 
-impl TryFrom<u128> for Work {
-    type Error = ();
-
-    fn try_from(value: u128) -> Result<Self, Self::Error> {
-        if value == 0 {
-            Err(())
-        } else {
-            Ok(Work(value))
-        }
-    }
-}
-
 impl From<ExpandedDifficulty> for CompactDifficulty {
     fn from(value: ExpandedDifficulty) -> Self {
         value.to_compact()
     }
 }
 
-impl From<Work> for CompactDifficulty {
-    fn from(value: Work) -> Self {
-        let expanded = ExpandedDifficulty::from(value);
-        Self::from(expanded)
-    }
-}
-
-impl From<Work> for ExpandedDifficulty {
-    fn from(value: Work) -> Self {
-        let work: U256 = value.0.into();
-        let expanded = (!work + 1) / work;
-        ExpandedDifficulty(expanded)
-    }
-}
-
 impl ExpandedDifficulty {
     /// Returns the difficulty of the hash.
     ///

zebra-state/Cargo.toml

@@ -35,3 +35,4 @@ spandoc = "0.2"
 tempdir = "0.3.7"
 tokio = { version = "0.2.22", features = ["full"] }
 proptest = "0.10.1"
+primitive-types = "0.7.2"

zebra-state/src/tests.rs

@@ -4,6 +4,7 @@ use zebra_chain::{
     block::{self, Block},
     transaction::Transaction,
     transparent,
+    work::difficulty::ExpandedDifficulty,
     work::difficulty::Work,
 };
 
@@ -42,9 +43,14 @@ impl FakeChainHelper for Arc<Block> {
     }
 
     fn set_work(mut self, work: u128) -> Arc<Block> {
-        let work = Work::try_from(work).expect("tests should only pass in valid work values");
+        use primitive_types::U256;
+
+        let work: U256 = work.into();
+        let expanded = (!work + 1) / work;
+        let expanded = ExpandedDifficulty::from(expanded);
+
         let block = Arc::make_mut(&mut self);
-        block.header.difficulty_threshold = work.into();
+        block.header.difficulty_threshold = expanded.into();
         self
     }
 }