Re: [PATCH v4 4/4] t0060: verify that basename() and dirname() work as expected

Unfortunately, some libgen implementations yield outcomes different
from what Git expects. For example, mingw-w64-crt provides a basename()
function, that shortens `path0/` to `path`!

So let's verify that the basename() and dirname() functions we use
conform to what Git expects.

Derived-from-code-by: Ramsay Jones [off-list ref]
Signed-off-by: Johannes Schindelin <redacted>
---
 t/t0060-path-utils.sh |   3 +
 test-path-utils.c     | 166 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 169 insertions(+)

diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index 627ef85..f0152a7 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh

@@ -59,6 +59,9 @@ case $(uname -s) in
 	;;
 esac
 
+test_expect_success basename 'test-path-utils basename'
+test_expect_success dirname 'test-path-utils dirname'
+
 norm_path "" ""
 norm_path . ""
 norm_path ./ ""

diff --git a/test-path-utils.c b/test-path-utils.c
index c67bf65..4ab68ac 100644
--- a/test-path-utils.c
+++ b/test-path-utils.c

@@ -39,6 +39,166 @@ static void normalize_argv_string(const char **var, const char *input)
 		die("Bad value: %s\n", input);
 }
 
+struct test_data {
+	const char *from;  /* input:  transform from this ... */
+	const char *to;    /* output: ... to this.            */
+};
+
+static int test_function(struct test_data *data, char *(*func)(char *input),
+	const char *funcname)
+{
+	int failed = 0, i;
+	char buffer[1024];
+	char *to;
+
+	for (i = 0; data[i].to; i++) {
+		if (!data[i].from)
+			to = func(NULL);
+		else {
+			strcpy(buffer, data[i].from);
+			to = func(buffer);
+		}
+		if (strcmp(to, data[i].to)) {
+			error("FAIL: %s(%s) => '%s' != '%s'\n",
+				funcname, data[i].from, to, data[i].to);
+			failed = 1;
+		}
+	}
+	return failed;
+}
+
+static struct test_data basename_data[] = {
+	/* --- POSIX type paths --- */
+	{ NULL,              "."    },
+	{ "",                "."    },
+	{ ".",               "."    },
+	{ "..",              ".."   },
+	{ "/",               "/"    },
+#if defined(__CYGWIN__) && !defined(NO_LIBGEN_H)
+	{ "//",              "//"   },
+	{ "///",             "//"   },
+	{ "////",            "//"   },
+#else
+	{ "//",              "/"    },
+	{ "///",             "/"    },
+	{ "////",            "/"    },
+#endif
+	{ "usr",             "usr"  },
+	{ "/usr",            "usr"  },
+	{ "/usr/",           "usr"  },
+	{ "/usr//",          "usr"  },
+	{ "/usr/lib",        "lib"  },
+	{ "usr/lib",         "lib"  },
+	{ "usr/lib///",      "lib"  },
+
+#if defined(__MINGW32__) || defined(_MSC_VER)
+
+	/* --- win32 type paths --- */
+	{ "\\usr",           "usr"  },
+	{ "\\usr\\",         "usr"  },
+	{ "\\usr\\\\",       "usr"  },
+	{ "\\usr\\lib",      "lib"  },
+	{ "usr\\lib",        "lib"  },
+	{ "usr\\lib\\\\\\",  "lib"  },
+	{ "C:/usr",          "usr"  },
+	{ "C:/usr",          "usr"  },