feat: support parsing scheme-only DSNs

[ChiragAgg5k]

Summary

This PR adds support for parsing scheme-only DSNs like local://, memory://, file:// etc.

Changes

• Made host property nullable to support DSNs without a host
• Updated getHost() return type from string to ?string
• Added special handling for scheme-only DSNs (e.g., local://) which PHP's parse_url returns false for
• Added tests for scheme-only DSN parsing

Example Usage

$dsn = new DSN('local://');
$dsn->getScheme(); // 'local'
$dsn->getHost();   // null

Summary by CodeRabbit

• New Features
  • DSN parser now supports scheme-only connection strings (e.g., "local://", "memory://", "file://")
  • Host parameter is now optional in DSN configurations

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

The changes modify the DSN class to support scheme-only DSN strings (e.g., "local://", "memory://"). The host property and its getter method are made nullable. The constructor is updated to short-circuit parsing for scheme-only DSNs, initializing all fields appropriately. Additionally, a new test method is added to verify DSN parsing behavior for scheme-only cases, and an existing test input is updated to use a different invalid DSN string.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

• Constructor logic changes: Review the scheme-only DSN handling path to ensure it correctly initializes all fields and prevents parse failures
• Null propagation: Verify that all methods and callers that use the host property handle the nullable type correctly
• Test coverage: Confirm that the new testSchemeOnly() test adequately covers all scheme-only DSN variations and edge cases
• Related methods: Check if other methods in the DSN class that depend on host property need adjustments for nullable type handling

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: adding support for parsing scheme-only DSNs, which is exactly what the changeset implements.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/support-scheme-only-dsn

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (2)

tests/DSN/DSNTest.php (1)

151-179: Scheme-only DSN tests align well with the new behavior

Assertions for scheme, null user/password/host/port, empty path, and null query for local://, memory://, and file:// match the constructor’s scheme-only initialization and give good coverage. If you ever add more such schemes, a data provider could de-duplicate this, but it’s not required.

src/DSN/DSN.php (1)

58-69: Scheme-only DSN handling works but could be more version-robust

The early-return branch cleanly initializes all fields for scheme-only DSNs and matches the new tests. Two things to verify/consider:

1. PHP version constraint – \str_ends_with() is PHP 8.0+, so this effectively requires PHP ≥ 8 unless you already enforce that elsewhere or provide a polyfill.
2. Reliance on parse_url() returning false – behavior for inputs like 'local://' is quirky across PHP versions; tying scheme-only detection to !$parts may be brittle.

A more robust pattern would be to detect scheme-only DSNs before calling parse_url(), e.g. via a simple regex, and bypass parse_url() entirely in that case:

-        $parts = \parse_url($dsn);
-
-        // Handle scheme-only DSNs like "local://" which parse_url returns false for
-        if (!$parts && \str_ends_with($dsn, '://') && \strlen($dsn) > 3) {
+        // Handle scheme-only DSNs like "local://", "memory://", "file://"
+        if (\preg_match('~^[A-Za-z][A-Za-z0-9+\-.]*://$~', $dsn) === 1) {
             $this->scheme = \substr($dsn, 0, -3);
             $this->user = null;
             $this->password = null;
             $this->host = null;
             $this->port = null;
             $this->path = '';
             $this->query = null;
 
             return;
         }
 
+        $parts = \parse_url($dsn);
+
         if (!$parts) {
             throw new \InvalidArgumentException("Unable to parse DSN: $dsn");
         }

This avoids depending on the exact parse_url() behavior and removes the need for str_ends_with().

Please verify against your supported PHP versions that parse_url() behaves as assumed today, and decide whether you want to adopt this more explicit detection to future‑proof the behavior.

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 42ee37a and c39e37d.

📒 Files selected for processing (2)

• src/DSN/DSN.php (4 hunks)
• tests/DSN/DSNTest.php (1 hunks)

🧰 Additional context used

🧬 Code graph analysis (1)

tests/DSN/DSNTest.php (1)

src/DSN/DSN.php (1)

• DSN (5-177)

🔇 Additional comments (2)

tests/DSN/DSNTest.php (1)

181-185: Updated failing DSN keeps negative coverage consistent with new semantics

Switching testFail() to use 'invalid-dsn-without-scheme' correctly targets the “missing scheme” path while allowing scheme-only DSNs like mariadb:// to be valid under the new rules.

src/DSN/DSN.php (1)

23-26: Host nullability is wired through correctly; confirm BC/semver expectations

Making $host nullable and propagating that through assignment and getHost(): ?string is internally consistent and matches the scheme-only DSN behavior where there genuinely is no host. This does, however, change the public API contract of getHost() from string to ?string, which can break strict-typed consumers expecting a non-nullable string.

Please double‑check that:

• The package versioning (and changelog) explicitly call out this return-type change, or
• All known consumers can handle null from getHost().

Also applies to: 82-82, 121-125