test(hash): add unit tests for Hash, Hash determinism, and Md5Hex edg…

[amshithnair]

Problem

The Hash() function in core/hash/hash.go (murmur3 wrapper) has no dedicated unit test. Only Md5() and Md5Hex() are directly tested. While Hash() is exercised indirectly through consistenthash_test.go, the function itself lacks isolated coverage.

Solution

Added 4 new test cases to core/hash/hash_test.go:

Test	Purpose
TestHash	Verifies Hash() returns a non-zero value for non-empty input
TestHash_Deterministic	Verifies identical inputs always produce the same hash
TestHash_Empty	Ensures Hash() does not panic on empty byte slice
TestMd5Hex_Empty	Validates Md5Hex() returns a valid 32-char hex string for empty input

Impact

• Test-only change — no production code modified
• No public API changes
• No breaking changes

Testing performed

go test -v -count=1 ./core/hash/...   # PASS
go vet ./core/hash/...                # PASS

Files changed

• core/hash/hash_test.go — added 4 test functions

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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