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1>------ Build started: Project: protobuf_net, Configuration: Debug Any CPU ------
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1> Build succeeded.
1> 0 Warning(s).
1> 0 Error(s).
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1> Time elapsed 00:00:00.2370835
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2>------ Build started: Project: Protobuf.Tests, Configuration: Debug Any CPU ------
2>D:\Dev\protobuf-net\Examples\Arrays.cs(4,7,4,12): DNX 4.5.1 error CS0246: The type or namespace name 'NUnit' could not be found (are you missing a using directive or an assembly reference?)
2>D:\Dev\protobuf-net\Examples\AutoFields.cs(6,7,6,12): DNX 4.5.1 error CS0246: The type or namespace name 'NUnit' could not be found (are you missing a using directive or an assembly reference?)
2>D:\Dev\protobuf-net\Examples\AutoTuple.cs(3,7,3,12): DNX 4.5.1 error CS0246: The type or namespace name 'NUnit' could not be found (are you missing a using directive or an assembly reference?)
2>D:\Dev\protobuf-net\Examples\Callbacks.cs(3,7,3,12): DNX 4.5.1 error CS0246: The type or namespace name 'NUnit' could not be found (are you missing a using directive or an assembly reference?)
(and so on for ... well, ages)
2>D:\Dev\protobuf-net\Examples\Primatives.cs(561,17,561,23): DNX Core 5.0 error CS0103: The name 'Assert' does not exist in the current context
2>D:\Dev\protobuf-net\Examples\Primatives.cs(567,17,567,23): DNX Core 5.0 error CS0103: The name 'Assert' does not exist in the current context
2>D:\Dev\protobuf-net\Examples\SimpleStream\SimpleStreamDemo.cs(317,24,317,31): DNX Core 5.0 warning CS0219: The variable 'psClone' is assigned but its value is never used
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2> Build failed.
2> 1 Warning(s).
2> 2431 Error(s).
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2> Time elapsed 00:00:01.0541880
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========== Build: 1 succeeded or up-to-date, 1 failed, 0 skipped ==========
Edit: is this possibly a "we aren't going to show more than 1000 errors in the IDE" check? If so, I suggest putting in at least one (presumably in the highest level severity encountered), i.e. in the above "There are more than {0} build errors; please see build output" (or "build warnings" in the warnings tab if only warnings were seen, etc)