Move tests to separate directories, and document

Today, with the tests inside a `tests` intermingled with the
corresponding library's source code, we have a few problems:

- We have to be careful that wildcards don't end up with tests being
  built as part of Nix proper, or test headers being installed as part
  of Nix proper.

- Tests in libraries but not executables is not right:

  - It means each executable runs the previous unit tests again, because
    it needs the libraries.

  - It doesn't work right on Windows, which doesn't want you to load a
    DLL just for the side global variable . It could be made to work
    with the dlopen equivalent, but that's gross!

This reorg solves these problems.

There is a remaining problem which is that sibbling headers (like
`hash.hh` the test header vs `hash.hh` the main `libnixutil` header) end
up shadowing each other. This PR doesn't solve that. That is left as
future work for a future PR.

Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>

(cherry picked from commit 91b6833686a6a6d9eac7f3f66393ec89ef1d3b57)
(cherry picked from commit a61e42adb528b3d40ce43e07c79368d779a8b624)

1 files changed, 66 insertions, 0 deletions

diff --git a/tests/unit/libutil/hilite.cc b/tests/unit/libutil/hilite.cc
new file mode 100644
index 000000000..1ff5980d5
--- /dev/null
+++ b/tests/unit/libutil/hilite.cc
@@ -0,0 +1,66 @@
+#include "hilite.hh"
+
+#include <gtest/gtest.h>
+
+namespace nix {
+/* ----------- tests for fmt.hh -------------------------------------------------*/
+
+    TEST(hiliteMatches, noHighlight) {
+        ASSERT_STREQ(hiliteMatches("Hello, world!", std::vector<std::smatch>(), "(", ")").c_str(), "Hello, world!");
+    }
+
+    TEST(hiliteMatches, simpleHighlight) {
+        std::string str = "Hello, world!";
+        std::regex re = std::regex("world");
+        auto matches = std::vector(std::sregex_iterator(str.begin(), str.end(), re), std::sregex_iterator());
+        ASSERT_STREQ(
+                    hiliteMatches(str, matches, "(", ")").c_str(),
+                    "Hello, (world)!"
+        );
+    }
+
+    TEST(hiliteMatches, multipleMatches) {
+        std::string str = "Hello, world, world, world, world, world, world, Hello!";
+        std::regex re = std::regex("world");
+        auto matches = std::vector(std::sregex_iterator(str.begin(), str.end(), re), std::sregex_iterator());
+        ASSERT_STREQ(
+                    hiliteMatches(str, matches, "(", ")").c_str(),
+                    "Hello, (world), (world), (world), (world), (world), (world), Hello!"
+        );
+    }
+
+    TEST(hiliteMatches, overlappingMatches) {
+        std::string str = "world, Hello, world, Hello, world, Hello, world, Hello, world!";
+        std::regex re = std::regex("Hello, world");
+        std::regex re2 = std::regex("world, Hello");
+        auto v = std::vector(std::sregex_iterator(str.begin(), str.end(), re), std::sregex_iterator());
+        for(auto it = std::sregex_iterator(str.begin(), str.end(), re2); it != std::sregex_iterator(); ++it) {
+            v.push_back(*it);
+        }
+        ASSERT_STREQ(
+                    hiliteMatches(str, v, "(", ")").c_str(),
+                    "(world, Hello, world, Hello, world, Hello, world, Hello, world)!"
+        );
+    }
+
+    TEST(hiliteMatches, complexOverlappingMatches) {
+        std::string str = "legacyPackages.x86_64-linux.git-crypt";
+        std::vector regexes = {
+            std::regex("t-cry"),
+            std::regex("ux\\.git-cry"),
+            std::regex("git-c"),
+            std::regex("pt"),
+        };
+        std::vector<std::smatch> matches;
+        for(auto regex : regexes)
+        {
+            for(auto it = std::sregex_iterator(str.begin(), str.end(), regex); it != std::sregex_iterator(); ++it) {
+                matches.push_back(*it);
+            }
+        }
+        ASSERT_STREQ(
+                    hiliteMatches(str, matches, "(", ")").c_str(),
+                    "legacyPackages.x86_64-lin(ux.git-crypt)"
+        );
+    }
+}