Fixing reading of multiple app context switches from a single AppContextSwitchOverrides configuration field.

[tetolv]

Description

SqlAppContextSwitchManager was unable to correctly parse multiple switches from the single configuration field. In case of such sample configuration:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section type="Microsoft.Data.SqlClient.AppContextSwitchOverridesSection, Microsoft.Data.SqlClient" name="AppContextSwitchOverrides"/>
  </configSections>
  <AppContextSwitchOverrides value="Switch.Microsoft.Data.SqlClient.EnableUserAgent=true;Switch.Microsoft.Data.SqlClient.UseCompatibilityProcessSni=true;System.Globalization.Invariant=false;"/>
</configuration>

following parsing code :

            string[] switches = appContextSwitches.Value?.Split('=', ';');
            ...
            for (int i = 0; i < switches.Length / 2; i++)
            {
                try
                {
                    AppContext.SetSwitch(switches[i], Convert.ToBoolean(switches[i + 1]));
                    SqlClientEventSource.Log.TryTraceEvent("<sc.{0}.{1}|INFO> Successfully assigned the AppContext switch '{2}'={3}.",
                                                           TypeName, methodName, switches[i], switches[i + 1]);
                }
                ...
            }

, on the second iteration would confuse switch key with a value and would try to convert key name to bool, which would of course fail.

One additional fix is for proper handling of configuration field, if it's content (sequence of switch=value pairs) starts, or ends with semicolon.

Testing

Changes seems trivial, bet unittests could be added, if deemed necessary.

[paulmedynski]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[paulmedynski]

Great catch! We clearly lack any unit tests for this, so I'll add that to the pile.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.69%. Comparing base (f06e783) to head (bf3de46).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
...ta/SqlClient/SqlAppContextSwitchManager.netcore.cs	0.00%	2 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (f06e783) and HEAD (bf3de46). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (f06e783)	HEAD (bf3de46)
addons	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3960       +/-   ##
===========================================
- Coverage   90.82%   67.69%   -23.14%     
===========================================
  Files           6      260      +254     
  Lines         316    65724    +65408     
===========================================
+ Hits          287    44490    +44203     
- Misses         29    21234    +21205     

Flag	Coverage Δ
addons	?
netcore	67.85% <0.00%> (?)
netfx	66.44% <ø> (?)

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