Add basic benchmark (#3038)

* Add basic benchmark

* Add basic documentation for how to run and add tests/benchmarks

* Update benchmark example output

* Add changelog entry

Co-authored-by: zneix <zneix@zneix.eu>

docs/test-and-benchmark.md

@@ -0,0 +1,88 @@
+# Test and Benchmark
+
+Chatterino includes a set of unit tests and benchmarks. These can be built using cmake by adding the `-DBUILD_TESTS=On` and `-DBUILD_BENCHMARKS=On` flags respectively.
+
+## Adding your own test
+
+1. Create a new file for the file you're adding tests for. If you're creating tests for `src/providers/emoji/Emojis.cpp`, create `tests/src/Emojis.cpp`.
+2. Add the newly created file to `tests/CMakeLists.txt` in the `test_SOURCES` variable (see the comment near it)
+
+See `tests/src/Emojis.cpp` for simple tests you can base your tests off of.
+
+Read up on http://google.github.io/googletest/primer.html to figure out how GoogleTest works.
+
+## Building and running tests
+
+```sh
+mkdir build-tests
+cd build-tests
+cmake -DBUILD_TESTS=On ..
+make
+./bin/chatterino-test
+```
+
+### Example output
+
+```
+[==========] Running 26 tests from 8 test suites.
+[----------] Global test environment set-up.
+[----------] 2 tests from AccessGuardLocker
+[ RUN      ] AccessGuardLocker.NonConcurrentUsage
+[       OK ] AccessGuardLocker.NonConcurrentUsage (0 ms)
+[ RUN      ] AccessGuardLocker.ConcurrentUsage
+[       OK ] AccessGuardLocker.ConcurrentUsage (686 ms)
+[----------] 2 tests from AccessGuardLocker (686 ms total)
+
+[----------] 4 tests from NetworkCommon
+[ RUN      ] NetworkCommon.parseHeaderList1
+[       OK ] NetworkCommon.parseHeaderList1 (0 ms)
+[ RUN      ] NetworkCommon.parseHeaderListTrimmed
+[       OK ] NetworkCommon.parseHeaderListTrimmed (0 ms)
+[ RUN      ] NetworkCommon.parseHeaderListColonInValue
+...
+[ RUN      ] TwitchAccount.NotEnoughForMoreThanOneBatch
+[       OK ] TwitchAccount.NotEnoughForMoreThanOneBatch (0 ms)
+[ RUN      ] TwitchAccount.BatchThreeParts
+[       OK ] TwitchAccount.BatchThreeParts (0 ms)
+[----------] 3 tests from TwitchAccount (2 ms total)
+
+[----------] Global test environment tear-down
+[==========] 26 tests from 8 test suites ran. (10297 ms total)
+[  PASSED  ] 26 tests.
+```
+
+## Adding your own benchmark
+
+1. Create a new file for the file you're adding benchmark for. If you're creating benchmarks for `src/providers/emoji/Emojis.cpp`, create `benchmarks/src/Emojis.cpp`.
+2. Add the newly created file to `benchmarks/CMakeLists.txt` in the `benchmark_SOURCES` variable (see the comment near it)
+
+See `benchmarks/src/Emojis.cpp` for simple benchmark you can base your benchmarks off of.
+
+## Building and running benchmarks
+
+```sh
+mkdir build-benchmarks
+cd build-benchmarks
+cmake -DBUILD_BENCHMARKS=On ..
+make
+./bin/chatterino-benchmark
+```
+
+### Example output
+
+```
+2021-07-18T13:12:11+02:00
+Running ./bin/chatterino-benchmark
+Run on (12 X 4000 MHz CPU s)
+CPU Caches:
+  L1 Data 32 KiB (x6)
+  L1 Instruction 32 KiB (x6)
+  L2 Unified 256 KiB (x6)
+  L3 Unified 15360 KiB (x1)
+Load Average: 2.86, 3.08, 3.51
+***WARNING*** CPU scaling is enabled, the benchmark real time measurements may be noisy and will incur extra overhead.
+--------------------------------------------------------------
+Benchmark                    Time             CPU   Iterations
+--------------------------------------------------------------
+BM_ShortcodeParsing       2394 ns         2389 ns       278933
+```