test(spanner): replace fixed hashCode value assertions with contract-compliance tests in OptionsTest

[anishesg]

OptionsTest contained four assertions that verified Options#hashCode() returns specific fixed integer values (31, 108027089, -2118248262). The Java hashCode() contract does not guarantee cross-JVM or cross-version stability of hash values, so testing against hardcoded numbers is brittle and misleads readers into thinking fixed values are part of the API contract.

This change replaces each fixed-value assertion in allOptionsAbsent, listOptionsTest, updateOptionsTest, and transactionOptionsTest with contract-compliance assertions: two equal Options instances produce equal hash codes, and calling hashCode() twice on the same instance returns the same value (stability within a session).

Fixes #12268

[gemini-code-assist]

Code Review

This pull request updates OptionsTest.java to replace hardcoded hash code values with dynamic assertions that verify the hashCode contract between equal objects. The review feedback suggests removing redundant tautological assertions where an object's hash code is compared to itself and recommends using more idiomatic AssertJ assertions for object equality to provide better failure messages.

[gemini-code-assist]

The assertion assertThat(options.hashCode()).isEqualTo(options.hashCode()) is a tautology and provides little value in a unit test for a value-like object. Additionally, using assertThat(options).isEqualTo(options2) is more idiomatic and provides better failure messages than assertThat(options.equals(options2)).isTrue().

Suggested change

	// Verify hashCode contract: equal objects must have equal hashCodes, and hashCode is stable.
	Options options2 = Options.fromReadOptions();
	assertThat(options.equals(options2)).isTrue();
	assertThat(options.hashCode()).isEqualTo(options2.hashCode());
	assertThat(options.hashCode()).isEqualTo(options.hashCode());
	// Verify hashCode contract: equal objects must have equal hashCodes.
	Options options2 = Options.fromReadOptions();
	assertThat(options).isEqualTo(options2);
	assertThat(options.hashCode()).isEqualTo(options2.hashCode());

[gemini-code-assist]

The assertion assertThat(options.hashCode()).isEqualTo(options.hashCode()) is a tautology and provides little value in a unit test for a value-like object. Additionally, using assertThat(options).isEqualTo(options2) is more idiomatic and provides better failure messages than assertThat(options.equals(options2)).isTrue().

Suggested change

	// Verify hashCode contract: equal objects must have equal hashCodes, and hashCode is stable.
	Options options2 =
	Options.fromListOptions(
	Options.pageSize(pageSize), Options.pageToken(pageToken), Options.filter(filter));
	assertThat(options.equals(options2)).isTrue();
	assertThat(options.hashCode()).isEqualTo(options2.hashCode());
	assertThat(options.hashCode()).isEqualTo(options.hashCode());
	// Verify hashCode contract: equal objects must have equal hashCodes.
	Options options2 =
	Options.fromListOptions(
	Options.pageSize(pageSize), Options.pageToken(pageToken), Options.filter(filter));
	assertThat(options).isEqualTo(options2);
	assertThat(options.hashCode()).isEqualTo(options2.hashCode());

[gemini-code-assist]

The assertion assertThat(options.hashCode()).isEqualTo(options.hashCode()) is a tautology and provides little value in a unit test for a value-like object. Additionally, using assertThat(options).isEqualTo(options2) is more idiomatic and provides better failure messages than assertThat(options.equals(options2)).isTrue().

Suggested change

	// Verify hashCode contract: equal objects must have equal hashCodes, and hashCode is stable.
	Options options2 = Options.fromUpdateOptions(Options.tag(tag));
	assertThat(options.equals(options2)).isTrue();
	assertThat(options.hashCode()).isEqualTo(options2.hashCode());
	assertThat(options.hashCode()).isEqualTo(options.hashCode());
	// Verify hashCode contract: equal objects must have equal hashCodes.
	Options options2 = Options.fromUpdateOptions(Options.tag(tag));
	assertThat(options).isEqualTo(options2);
	assertThat(options.hashCode()).isEqualTo(options2.hashCode());

[gemini-code-assist]

The assertion assertThat(options.hashCode()).isEqualTo(options.hashCode()) is a tautology and provides little value in a unit test for a value-like object. Additionally, using assertThat(options).isEqualTo(options2) is more idiomatic and provides better failure messages than assertThat(options.equals(options2)).isTrue().

Suggested change

	// Verify hashCode contract: equal objects must have equal hashCodes, and hashCode is stable.
	Options options2 = Options.fromTransactionOptions(Options.tag(tag));
	assertThat(options.equals(options2)).isTrue();
	assertThat(options.hashCode()).isEqualTo(options2.hashCode());
	assertThat(options.hashCode()).isEqualTo(options.hashCode());
	// Verify hashCode contract: equal objects must have equal hashCodes.
	Options options2 = Options.fromTransactionOptions(Options.tag(tag));
	assertThat(options).isEqualTo(options2);
	assertThat(options.hashCode()).isEqualTo(options2.hashCode());