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Testing SHA256 Hash Generation Implementation in github-linguist/linguist

This test suite validates SHA256 hashing functionality in the Linguist module, ensuring consistent hexdigest generation across different Ruby data types and structures.

Test Coverage Overview

The test suite provides comprehensive coverage of SHA256 hexdigest generation across multiple data types including strings, symbols, integers, booleans, nil values, arrays, and hashes.

Key functionality tested includes:

Consistent hash generation for primitive types
Version-specific integer handling for Ruby 2.4.0+
Hash order independence verification
Type-specific hash uniqueness validation

Implementation Analysis

The testing approach uses Minitest framework with systematic verification of hexdigest outputs for each data type. The implementation employs assertion-based testing patterns with explicit expected hash values and refutation tests to verify type-specific hash uniqueness.

Technical patterns include:

Ruby version conditional testing
Hash ordering verification
Cross-type hash comparison
Nested data structure handling

Technical Details

Testing tools and configuration:

Minitest test framework
Linguist module integration
Ruby version detection using Gem::Version
Relative helper file inclusion
SHA256 class implementation

Best Practices Demonstrated

The test suite exemplifies robust testing practices through comprehensive type coverage and edge case handling. Notable practices include:

Explicit version compatibility handling
Systematic data type testing
Clear test case organization
Defensive hash comparison testing
Consistent assertion patterns

github-linguist/linguist

test/test_sha256.rb

            
require_relative "./helper"

class TestSHA256 < Minitest::Test
  include Linguist

  def test_hexdigest_string
    assert_equal "15020d93a6f635366cb20229cb3931c3651992dc6df85cddecc743fa11e48a66", SHA256.hexdigest("foo")
    assert_equal "3da77c2b08c7d29fe3d936b7918039941c0881065dde07d0af9d280d2d475d00", SHA256.hexdigest("bar")
  end

  def test_hexdigest_symbol
    assert_equal "dea6712e86478d2ee22a35a8c5ac9627e7cbc5ce2407a7da7c645fea2434fe9b", SHA256.hexdigest(:foo)
    assert_equal "9e414b095a78ef4c2ae6f74dc6898f653c6590554ff36719d4803733a6d910e3", SHA256.hexdigest(:bar)

    refute_equal SHA256.hexdigest("foo"), SHA256.hexdigest(:foo)
  end

  def test_hexdigest_integer
    # Ruby 2.4.0 merged Bignum and Fixnum into Integer which means we get different digests
    if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new("2.4.0")
      assert_equal "e2e98cd680460c0cecd76714d94e601be9b629ad16ae45251fa30366f62007bb", SHA256.hexdigest(1)
      assert_equal "88159e413c4a97194ee0d8b082ebfd54ce3f9985b58270d3bf59a6e6186f8da6", SHA256.hexdigest(2)
    else
      assert_equal "d9af1c504ce3dc080973d6de94d44884482fcee3ff04fd430c5aba2e4d1ba2cd", SHA256.hexdigest(1)
      assert_equal "1a4dfbfcf67bc80f3dbade7083386362d8f40db225cbd8e41e61199599f334c3", SHA256.hexdigest(2)
    end

    refute_equal SHA256.hexdigest("1"), SHA256.hexdigest(1)
  end

  def test_hexdigest_boolean
    assert_equal "92de503a8b413365fc38050c7dd4bacf28b0f705e744dacebcaa89f2032dcd67", SHA256.hexdigest(true)
    assert_equal "bdfd64a7c8febcc3b0b8fb05d60c8e2a4cb6b8c081fcba20db1c9778e9beaf89", SHA256.hexdigest(false)

    refute_equal SHA256.hexdigest("true"), SHA256.hexdigest(true)
    refute_equal SHA256.hexdigest("false"), SHA256.hexdigest(false)
  end

  def test_hexdigest_nil
    assert_equal "9bda381dac87b1c16b04f996abb623f43f1cdb89ce8be7dda3f67319dc440bc5", SHA256.hexdigest(nil)

    refute_equal SHA256.hexdigest("nil"), SHA256.hexdigest(nil)
  end

  def test_hexdigest_array
    assert_equal "f0cf39d0be3efbb6f86ac2404100ff7e055c17ded946a06808d66f89ca03a811", SHA256.hexdigest([])
    # Ruby 2.4.0 merged Bignum and Fixnum into Integer which means we get different digests
    if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new("2.4.0")
      assert_equal "e0ca0f6a274c6cc8e07fce6cf58cd2feef978928cad1c0760b6c3b8a865eafaf", SHA256.hexdigest([1])
      assert_equal "46b40ee5dcee74020fd75532659329e2a01b8cd74727218966c40cd1b4a54dab", SHA256.hexdigest([1, 2])
      assert_equal "0c950e57182b6830a3f4da3388fa7e3e5ec879277847c20b941f5a0144ba53a7", SHA256.hexdigest([1, 2, 3])
      assert_equal "0ef88eec0c680d3860c0001c6beb4407559d61db85744e088436a21d72425b4f", SHA256.hexdigest([1, 2, [3]])
    else
      assert_equal "87d177e40c167e5ce164081297c788c36540aa8f9cc05a0d1d3abfa577b56886", SHA256.hexdigest([1])
      assert_equal "c8189462e4785c786b96c8d29ecfa7c030010700dd1dfb194b84b37c50981feb", SHA256.hexdigest([1, 2])
      assert_equal "7edd426189105eede4954333ce40d96ff850ca86aa48e15b58cd017aab52c712", SHA256.hexdigest([1, 2, 3])
      assert_equal "b0f08d52b5efd5c44dc47965733ff8baac34db05abf2620a1f71c0fc0a7e42d2", SHA256.hexdigest([1, 2, [3]])
    end
  end

  def test_hexdigest_hash
    assert_equal "a91069147f9bd9245cdacaef8ead4c3578ed44f179d7eb6bd4690e62ba4658f2", SHA256.hexdigest({})
    # Ruby 2.4.0 merged Bignum and Fixnum into Integer which means we get different digests
    if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new("2.4.0")
      assert_equal "124c84e8bf1fe4be4d2c3e5d79522972f390dbf6031dd8ba7029793f2fec0ef7", SHA256.hexdigest({:a => 1})
      assert_equal "8a1c987468032f979d4a7d4eeb5049bfe0aa04acea54a4456888e2898dd1c532", SHA256.hexdigest({:b => 2})
    else
      assert_equal "7ae6ddefc4ec3fca1ca84794904144cdc99ca24444fcb44c05c0f269af8c8840", SHA256.hexdigest({:a => 1})
      assert_equal "484ca3e0efd43e7d650189150751512a3c985957f4c15b52da0bb12d72b3dcaa", SHA256.hexdigest({:b => 2})
    end

    refute_equal SHA256.hexdigest([:b, 2]), SHA256.hexdigest({:b => 2})

    assert_equal SHA256.hexdigest({:b => 2, :a => 1}), SHA256.hexdigest({:a => 1, :b => 2})
    assert_equal SHA256.hexdigest({:c => 3, :b => 2, :a => 1}), SHA256.hexdigest({:a => 1, :b => 2, :c => 3})
  end
end