imm32: Add some really basic tests for ImmSetCompositionString().

[Dmitry Timoshkov]

"Andrew Riedi" <andrewriedi at gmail.com> wrote:

> +static int test_ImmSetCompositionString(void)

It's a usual practice to have the test cases return 'void',
especially if you don't use the return value.

> +{
> +    HIMC imc;
> +    BOOL ret;
> +    DWORD error;
> +
> +    imc = ImmGetContext(hwnd);

First thing to test is the return value of ImmGetContext() and report
last error in the case of a failure.

-- 
Dmitry.