Remove most instances ofcustom error checking from tests.

Patterns mostly were of the form:

```
if (someBooleanCondition)
{
    Assert.True(false, ....);
    // Or sometimes Assert.False(true, ....);
}
```
or
```
try
{
    SomeErrorThrowingOperation
    Assert.True(false, ....);
    // Or sometimes Assert.False(true, ....);
}
catch (ExpectedExceptionType e)
{
}
```
This replaces most instances with calls to the proper Xunit.Assert#### .
Some additional minor work was performed as noted with the affected package.

Add common ShouldNotBeInvokedException
System.Collections
 - Partially unwind edges of internal test framework.
System.Collections.Concurrent
 - Switch some tests to use InlineData instead of delegated method calls.
System.Collections.Immutable
 - Use ShouldNotBeInvokedException to state some lambdas should not be called.
System.Collections.NonGeneric
System.Composition
 - Partially unwind internal test famework.
 - Switch to using xunit asserts where possible.
System.Diagnostics.Contracts
 - Use ShouldNotBeInvokedException to state some lambdas should not be called.
 - Update project file to use upper case letter in hash.
System.Diagnostics.FileVersionInfo
 - Switch to direct equals comparison.
System.Diagnostics.Process
 - Use ShouldNotBeInvokedException to state a task should exit.
System.Diagnostics.Tracing.Telemetry
 - Use ShouldNotBeInvokedException to state an overridden method should not be called.
System.Globalization
 - Switch to direct equals comparisons in some cases.
System.Globalization.Extensions
 - Switch to direct equals comparison in some cases.
System.IO.Compression.ZipFile
System.IO.FileSystem
 - Partially unwind internal test framework.
System.IO.Packaging
 - Correct test T006 to check that adding absolute Uri part in internal mode is invalid.
System.ObjectModel
 - Use ShouldNotBeInvokedException to state some observables should execute.
System.Reflection
 - Update readonly-set test to verify that the field is set (previous test implied it was not).
System.Reflection.Extensions
System.Reflection.Metadata
 - Partially remove internal test framework.
 - Switch to xunit asserts where possible.
System.Reflection.TypeExtensions
System.Runtime
System.Runtime.Extensions
 - Switch to xunit bounded equals for doubles.
 - Switch to verifying non-varags Path.Combine override.
System.Runtime.Numerics
 - Switch to xunit Assert.Throws from internal version.
System.ServiceProcess.ServiceController
System.Text.Encoding
System.Text.Encodings.Web
System.Threading
System.Threading.Tasks.Dataflow
System.Threading.Tasks.Parallel
System.Xml.ReaderWriter
 - Switch to form verifying exception is thrown.
System.Xml.XmlDocument
 - Use ShouldNotBeInvokedException to state some handlers should not be called.

1 files changed, 0 insertions, 4 deletions

diff --git a/src/System.Collections.NonGeneric/tests/ArrayList/PropertyIsReadOnlyTests.cs b/src/System.Collections.NonGeneric/tests/ArrayList/PropertyIsReadOnlyTests.cs
index 757b3a7fb5..8082038459 100644
--- a/src/System.Collections.NonGeneric/tests/ArrayList/PropertyIsReadOnlyTests.cs
+++ b/src/System.Collections.NonGeneric/tests/ArrayList/PropertyIsReadOnlyTests.cs
@@ -72,10 +72,6 @@ namespace System.Collections.ArrayListTests
             alst3 = ArrayList.ReadOnly(alst2);
             Assert.True(alst2.IsReadOnly);
             Assert.True(alst3.IsReadOnly);
-            if (!alst3.IsReadOnly)
-            {
-                Assert.False(true, "Error, Expected value not returned, " + alst3.IsReadOnly);
-            }
 
             //[]we still cant access the 2nd one :)
             //we cant access remove or add to the readonly list