Fix Unicode issue in Contain and ContainExactly.

[tkirill]

fix #377

These are the only places where Get-Content is used in assertions.

[tkirill]

How I can fix the build? Locally I have all tests passed on powershell v4.

[dlwyatt]

Those timeouts indicate a problem on the build server, don't worry about it for now.

As for the PR, I'd be concerned with what happens if the code encounters a file that isn't ASCII or UTF-8. (Unicode / UTF-16, for instance, which are created by default when you use Out-File or the redirection operators.)

[tkirill]

@dlwyatt I took the character レ which takes 3 bytes 0xE3 0x83 0xAC in UTF-8. I saved the character in a file in UTF-16 with BOM and this test passed:

Describe "Get-Content" {
    It "magically works with UTF-16" {
        'test.txt' | Should Contain 'レ'

        $utf8 = Get-Content -Encoding UTF8 'test.txt'
        $utf16 = Get-Content -Encoding Unicode 'test.txt'
        $oem = Get-Content -Encoding Oem 'test.txt'

        $utf8 | Should Be 'レ'
        $utf16 | Should Be 'レ'
        $oem | Should Be 'レ'
    }
}

The test passes even without my changes but I don't know why. Maybe when Powershell sees BOM it assumes UTF-16 and doesn't look at -Encoding parameter? This is strange. Anyway, I think it would be right to say that this PR changes nothing for UTF-16.

Also, when save the character in UTF-8 this test

Describe "Should Contains" {
    It "works with UTF-8" {
        'test.txt' | Should Contain 'レ'

        $utf8 = Get-Content -Encoding UTF8 'test.txt'

        $utf8 | Should Be 'レ'
    }
}

fails without this PR.

[tkirill]

@dlwyatt If you don't like these changes I would be happy if you provide small instruction how to implement custom should assertions. It would solve my little problem too 👍

[dlwyatt]

Sorry about that, I lost track of this one. I'll look it over now and merge if everything seems okay