add ASCompletion.Test.Context.ASContextTest->TestGetCachedFileModel
Organize usings
Rename "ASContextTest->TestCreateFileModelForInvalidFile" by "ASContextTest->TestCreateFileModelForEmptyFileName"
Add ASContextTest->TestCreateFileModelForNullFileName
Rename "ASContextTest->TestGetFileModelForInvalidFile" by "ASContextTest->TestGetFileModelForEmptyFileName"
Add ASContextTest->TestGetFileModelForNullFileName
Replace "" by string.Empty
Implement ASContextTest->TestGetCachedFileModelForEmptyFileName
Add ASContextTest->TestGetCachedFileModelForNullFileName
Add ASContextTest->TestGetCachedFileModelForValidFile
Add ASContextTest->TestFilterSource
Add ASContextTest->TestIsModelValidForEmptyFileName
Replace ASContextTest->TestIsModelValidForEmptyFileName by ASContextTest->TestIsModelValidForNullFileModel
Add AScontextTest->TestIsModelValidForSomeFileModel
Add ASContextTest->TestGetDeclarationAtLineForEmptyContext
Add ASContexTest->TestGetDeclarationAtLine
Merge pull request #10 from SlavaRa/tests-ASCompletion.Test.Context.ASContextTest

Tests up