[duplicate-code] Duplicate Code: Shared Logic Between OdbcDataConnection and OleDataConnection

[Evangelink]

Analysis of commit 756cdee

Assignee: @copilot

Summary

OdbcDataConnection and OleDataConnection in src/Adapter/MSTestAdapter.PlatformServices/Data/ both extend TestDataConnectionSql and implement nearly the same database schema retrieval, identifier quoting, and connection-string fix-up logic. The two files are structurally very similar (~100 lines each), sharing identical patterns for GetTablesForSchema, QuoteIdentifier, UnquoteIdentifier, and connection-string path fixing — with differences only in the underlying ADO.NET provider types (Odbc* vs OleDb*).

Duplication Details

Pattern: Parallel ADO.NET Provider Implementations with Shared Logic

• Severity: Medium
• Occurrences: 2 files (~198 lines combined, ~60% structurally duplicated)
• Locations:
  • src/Adapter/MSTestAdapter.PlatformServices/Data/OdbcDataConnection.cs (lines 1–105)
  • src/Adapter/MSTestAdapter.PlatformServices/Data/OleDataConnection.cs (lines 1–93)

The files share:

Section	OdbcDataConnection	OleDataConnection
Constructor (lines 19–27)	Connection.Driver → IsMSSql(...)	Connection.Provider → IsMSSql(...)
CommandBuilder property	OdbcCommandBuilder cast	OleDbCommandBuilder cast
Connection property	OdbcConnection cast	OleDbConnection cast
QuoteIdentifier (lines 64–66)	CommandBuilder.QuoteIdentifier(id, Connection)	identical
UnquoteIdentifier (lines 70–72)	CommandBuilder.UnquoteIdentifier(id, Connection)	identical
FixupConnectionString pattern	DSN/Excel path fix	DataSource path fix
GetTablesForSchema structure	SchemaMetaData lookup	SchemaMetaData lookup

• Code Sample (identical quoting methods):

// OdbcDataConnection.cs (lines 63–73) — IDENTICAL in both files
protected override string QuoteIdentifier(string identifier)
{
    return CommandBuilder.QuoteIdentifier(identifier, Connection);  // Must pass connection.
}

protected override string UnquoteIdentifier(string identifier)
{
    return CommandBuilder.UnquoteIdentifier(identifier, Connection);  // Must pass connection.
}

// OleDataConnection.cs (lines 57–65) — structurally identical
protected override string QuoteIdentifier(string identifier)
{
    return CommandBuilder.QuoteIdentifier(identifier, Connection);
}

protected override string UnquoteIdentifier(string identifier)
{
    return CommandBuilder.UnquoteIdentifier(identifier, Connection);
}

Impact Analysis

• Maintainability: Any change to schema retrieval or quoting logic must be applied in parallel to both files. The GetTablesForSchema methods diverge in schema column names (TABLE_SCHEM vs TABLE_SCHEMA) and valid table types, making them harder to spot as candidates for sharing.
• Bug Risk: Medium — a fix to connection-string path normalization in one file may not be applied to the other.
• Code Bloat: ~60 lines of duplicated code between the two files.

Refactoring Recommendations

1. Move identical QuoteIdentifier/UnquoteIdentifier to the TestDataConnectionSql base class

   • Both implementations call CommandBuilder.QuoteIdentifier(identifier, Connection) identically. These two methods can be moved up to the base class and removed from both OdbcDataConnection and OleDataConnection.
   • The base class TestDataConnectionSql already owns CommandBuilder and Connection, so the move is straightforward.
   • File: src/Adapter/MSTestAdapter.PlatformServices/Data/TestDataConnectionSql.cs
   • Estimated effort: Low (2–4 hours)

2. Extract shared IsMSSql detection

   • Both constructors call IsMSSql(Connection.Driver) / IsMSSql(Connection.Provider) to set _isMSSql. The IsMSSql method is defined in TestDataConnectionSql. A virtual/abstract GetProviderName(DbConnection conn) hook on the base class could unify the constructor logic.

3. Consider a template-method pattern for FixupConnectionString

   • The path fix-up logic follows the same pattern (find file path → normalize → update connection string) but uses provider-specific ConnectionStringBuilder types. A protected virtual UpdateFilePath(string fixedPath) on the base class could handle the update step.

Implementation Checklist

• Review duplication findings
• Move QuoteIdentifier/UnquoteIdentifier to TestDataConnectionSql base class (lowest risk, highest impact)
• Add a virtual GetProviderName(DbConnection) to unify the _isMSSql assignment pattern
• Evaluate feasibility of a template-method for FixupConnectionString
• Run MSTestAdapter.PlatformServices unit/integration tests to confirm no regressions

Analysis Metadata

• Analyzed Files: 2 (OdbcDataConnection.cs, OleDataConnection.cs) + base class (TestDataConnectionSql.cs)
• Detection Method: Semantic code analysis + structural diff
• Commit: 756cdee
• Analysis Date: 2026-06-06

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• expires on Jun 8, 2026, 5:37 AM UTC