1 files changed, 49 insertions, 0 deletions
diff --git a/test/unit/message_spec.lua b/test/unit/message_spec.lua
new file mode 100644
index 0000000000..23d342c027
--- /dev/null
+++ b/test/unit/message_spec.lua
@@ -0,0 +1,49 @@
+local helpers = require("test.unit.helpers")
+
+local ffi = helpers.ffi
+local eq = helpers.eq
+local to_cstr = helpers.to_cstr
+
+local cimp = helpers.cimport('./src/nvim/message.h')
+
+describe('trunc_string', function()
+  local buffer = ffi.typeof('char_u[40]')
+
+  local function test_inplace(s, expected)
+    local buf = buffer()
+    ffi.C.strcpy(buf, s)
+    cimp.trunc_string(buf, buf, 20, 40)
+    eq(expected, ffi.string(buf))
+  end
+
+  local function test_copy(s, expected)
+    local buf = buffer()
+    cimp.trunc_string(to_cstr(s), buf, 20, 40)
+    eq(expected, ffi.string(buf))
+  end
+
+  local permutations = {
+    { ['desc'] = 'in-place', ['func'] = test_inplace },
+    { ['desc'] = 'by copy', ['func'] = test_copy },
+  }
+
+  for _,t in ipairs(permutations) do
+    describe('populates buf '..t.desc, function()
+      it('with a small string', function()
+        t.func('text', 'text')
+      end)
+
+      it('with a medium string', function()
+        t.func('a short text', 'a short text')
+      end)
+
+      it('with a string exactly the truncate size', function()
+        t.func('a text tha just fits', 'a text tha just fits')
+      end)
+
+      it('with a string that must be truncated', function()
+        t.func('a text that nott fits', 'a text t...nott fits')
+      end)
+    end)
+  end
+end)