This is normal, as VS2015 runs tests in a number of threads. But at least the output log showing number of discovered tests should report also the source binary path or similar info. See e.g. this sample output:
------ Discover test started ------
NSpec VS Adapter 0.1.0.0: [INFO] Discovery started
NSpec VS Adapter 0.1.0.0: [INFO] Discovering tests in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\AdHocConsoleRunner\bin\Debug\AdHocConsoleRunner.exe'
NSpec VS Adapter 0.1.0.0: [INFO] Discovery started
NSpec VS Adapter 0.1.0.0: [INFO] Discovering tests in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\ConfigSampleSpecs\bin\Debug\ConfigSampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [DEBUG] Start collecting tests in 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\ConfigSampleSpecs\bin\Debug\ConfigSampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [DEBUG] Start collecting tests in 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\AdHocConsoleRunner\bin\Debug\AdHocConsoleRunner.exe'
NSpec VS Adapter 0.1.0.0: [INFO] Discovery started
NSpec VS Adapter 0.1.0.0: [INFO] Skipping binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\ConfigSampleSystem\bin\Debug\ConfigSampleSystem.exe' because it does not reference nspec library
NSpec VS Adapter 0.1.0.0: [INFO] Discovery finished
NSpec VS Adapter 0.1.0.0: [INFO] Discovery started
NSpec VS Adapter 0.1.0.0: [INFO] Skipping binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSystem\bin\Debug\SampleSystem.dll' because it does not reference nspec library
NSpec VS Adapter 0.1.0.0: [INFO] Discovery finished
NSpec VS Adapter 0.1.0.0: [INFO] Discovery started
NSpec VS Adapter 0.1.0.0: [INFO] Discovering tests in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [DEBUG] Start collecting tests in 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [DEBUG] Finish collecting tests in 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\AdHocConsoleRunner\bin\Debug\AdHocConsoleRunner.exe'
NSpec VS Adapter 0.1.0.0: [INFO] Found 0 tests
NSpec VS Adapter 0.1.0.0: [INFO] Discovery finished
NSpec VS Adapter 0.1.0.0: [TRACE] Debug info found for method 'SampleSpecs.ParentSpec'.'<method_context_1>b__2_0' in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [TRACE] Debug info found for method 'SampleSpecs.ParentSpec'.'<method_context_1>b__2_1' in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [TRACE] Debug info found for method 'SampleSpecs.ParentSpec'.'<method_context_2>b__3_0' in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [DEBUG] Cannot get debug info for method 'NSpec.nspec'.'<.ctor>b__0' in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [TRACE] Debug info found for method 'SampleSpecs.ChildSpec'.'<method_context_4>b__1_0' in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [TRACE] Debug info found for method 'SampleSpecs.ChildSpec'.'<method_context_5>b__2_1' in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [TRACE] Debug info found for method 'SampleSpecs.ChildSpec'.'<method_context_5>b__2_2' in binary 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [DEBUG] Finish collecting tests in 'D:\WS\NET\NSpec framework\NSpec.VsAdapter\src\NSpec.VsAdapter\Test\Samples\SampleSpecs\bin\Debug\SampleSpecs.dll'
NSpec VS Adapter 0.1.0.0: [INFO] Found 7 tests
NSpec VS Adapter 0.1.0.0: [INFO] Discovery finished
========== Discover test finished: 0 found (0:00:00,4990949) ==========
This is normal, as VS2015 runs tests in a number of threads. But at least the output log showing number of discovered tests should report also the source binary path or similar info. See e.g. this sample output: