self sub test

Author: thedavidmeister

.gas-snapshot

@@ -195,9 +195,10 @@ LibDecimalFloatImplementationPow10Test:testExactLookups() (gas: 1281984)
 LibDecimalFloatImplementationPow10Test:testExactPows() (gas: 1260129)
 LibDecimalFloatImplementationPow10Test:testInterpolatedLookupsPower() (gas: 1282922)
 LibDecimalFloatImplementationPow10Test:testNoRevert(int224,int32) (runs: 5103, μ: 1258761, ~: 1259054)
-LibDecimalFloatImplementationSubTest:testSubIsAdd(int256,int256,int256,int256) (runs: 5109, μ: 15686, ~: 15706)
-LibDecimalFloatImplementationSubTest:testSubMinSignedValue(int256,int256,int256) (runs: 5109, μ: 14809, ~: 14755)
-LibDecimalFloatImplementationSubTest:testSubOneFromMax() (gas: 5460)
+LibDecimalFloatImplementationSubTest:testSubIsAdd(int256,int256,int256,int256) (runs: 5109, μ: 15665, ~: 15684)
+LibDecimalFloatImplementationSubTest:testSubMinSignedValue(int256,int256,int256) (runs: 5109, μ: 14792, ~: 14735)
+LibDecimalFloatImplementationSubTest:testSubOneFromMax() (gas: 6435)
+LibDecimalFloatImplementationSubTest:testSubSelf(int224,int32) (runs: 5109, μ: 5346, ~: 5449)
 LibDecimalFloatImplementationWithTargetExponentTest:testWithTargetExponentExamples() (gas: 13429)
 LibDecimalFloatImplementationWithTargetExponentTest:testWithTargetExponentLargerExponentOverflowRescaleRevert(int256,int256,int256) (runs: 5101, μ: 14426, ~: 14395)
 LibDecimalFloatImplementationWithTargetExponentTest:testWithTargetExponentLargerExponentVeryLargeDiffRevert(int256,int256,int256) (runs: 5109, μ: 13307, ~: 13527)

test/src/lib/implementation/LibDecimalFloatImplementation.sub.t.sol

@@ -64,4 +64,11 @@ contract LibDecimalFloatImplementationSubTest is Test {
     function testSubOneFromMax() external pure {
         checkSub(type(int224).max, type(int32).max, 1, 0, int256(type(int224).max) * 1e8, type(int32).max - 8);
     }
+
+    function testSubSelf(int224 signedCoefficientA, int32 exponentA) external pure {
+        (int256 signedCoefficient, int256 exponent) =
+            LibDecimalFloatImplementation.sub(signedCoefficientA, exponentA, signedCoefficientA, exponentA);
+        (exponent);
+        assertEq(signedCoefficient, 0, "LibDecimalFloatImplementation.sub self coefficient");
+    }
 }