Valid TrustThresholdFraction and further simplify tests code (#142)

* Valid TrustThresholdFraction for real

* Further simplify tests: init requester with final state

* Apply review suggestions and assert_bisection_err fn

* remove redundant clone

* add another err case

* unpublicize verify_commit_full and verify_commit_trusting (ref #136)

* ensure the untrusted_header.bft_time() > trusted_header.bft_time()

* Fix failing test and test and add another erroring one

* remove dupl test

* Consistent comments in tests

* Refactor init_requester (#152)

* added bisection test for insufficient commits

* refactored init_requester, TODO: update tests

* fixed tests

* Added bisection test for insufficient commits

* fixed failures

* cargo fmt

* Changed tests to use ValsAndCommit struct

* satisfy clippy

* Dealing with the merge conflict's aftermath

Co-authored-by: Shivani Joshi <46731446+Shivani912@users.noreply.github.com>

tendermint/src/lite/error.rs

@@ -24,6 +24,10 @@ pub enum Kind {
     #[error("expected height >= {expected} (got: {got})")]
     NonIncreasingHeight { got: u64, expected: u64 },
 
+    /// Header time is in the past compared to already trusted header.
+    #[error("untrusted header time <= trusted header time")]
+    NonIncreasingTime,
+
     /// Invalid validator hash.
     #[error("header's validator hash does not match actual validator hash ({header_val_hash:?}!={val_hash:?})")]
     InvalidValidatorSet {

tendermint/src/lite/types.rs

@@ -94,16 +94,22 @@ pub struct TrustThresholdFraction {
 }
 
 impl TrustThresholdFraction {
-    pub fn new(numerator: u64, denominator: u64) -> Result<Self, Kind> {
-        if numerator <= denominator && denominator > 0 {
+    /// Instantiate a TrustThresholdFraction if the given denominator and
+    /// numerator are valid.
+    ///
+    /// The parameters are valid iff `1/3 <= numerator/denominator <= 1`.
+    /// In any other case we return [`Error::InvalidTrustThreshold`].
+    pub fn new(numerator: u64, denominator: u64) -> Result<Self, Error> {
+        if numerator <= denominator && denominator > 0 && 3 * numerator >= denominator {
             return Ok(Self {
                 numerator,
                 denominator,
             });
         }
         Err(Kind::InvalidTrustThreshold {
             got: format!("{}/{}", numerator, denominator),
-        })
+        }
+        .into())
     }
 }
 
@@ -227,6 +233,10 @@ pub(super) mod mocks {
                 next_vals,
             }
         }
+
+        pub fn set_time(&mut self, new_time: SystemTime) {
+            self.time = new_time
+        }
     }
 
     impl Header for MockHeader {
@@ -430,8 +440,13 @@ mod tests {
             TrustThresholdFraction::new(1, 3).expect("mustn't panic")
         );
         assert!(TrustThresholdFraction::new(2, 3).is_ok());
+        assert!(TrustThresholdFraction::new(1, 1).is_ok());
 
         assert!(TrustThresholdFraction::new(3, 1).is_err());
+        assert!(TrustThresholdFraction::new(1, 4).is_err());
+        assert!(TrustThresholdFraction::new(1, 5).is_err());
+        assert!(TrustThresholdFraction::new(2, 7).is_err());
+        assert!(TrustThresholdFraction::new(0, 1).is_err());
         assert!(TrustThresholdFraction::new(1, 0).is_err());
     }
 }