feat: detect upper case letters with get_substr_matcher (#2950)

* feat: detect upper case letters by substr matcher

* test: add tests for get_substr_matcher

lua/tests/automated/sorters_spec.lua

@@ -0,0 +1,84 @@
+local sorters = require "telescope.sorters"
+
+describe("get_substr_matcher", function()
+  local function with_smartcase(smartcase, case)
+    local original = vim.o.smartcase
+    vim.o.smartcase = smartcase
+
+    describe("scoring_function", function()
+      it(case.msg, function()
+        local matcher = sorters.get_substr_matcher()
+        assert.are.same(case.expected_score, matcher.scoring_function(_, case.prompt, _, case.entry))
+      end)
+    end)
+
+    describe("highlighter", function()
+      it("returns valid highlights", function()
+        local matcher = sorters.get_substr_matcher()
+        local highlights = matcher.highlighter(_, case.prompt, case.entry.ordinal)
+        table.sort(highlights, function(a, b)
+          return a.start < b.start
+        end)
+        assert.are.same(case.expected_highlights, highlights)
+      end)
+    end)
+
+    vim.o.smartcase = original
+  end
+
+  describe("when smartcase=OFF", function()
+    for _, case in ipairs {
+      {
+        msg = "doesn't match",
+        prompt = "abc def",
+        entry = { index = 3, ordinal = "abc d" },
+        expected_score = -1,
+        expected_highlights = { { start = 1, finish = 3 } },
+      },
+      {
+        msg = "matches with lower case letters only",
+        prompt = "abc def",
+        entry = { index = 3, ordinal = "abc def ghi" },
+        expected_score = 3,
+        expected_highlights = { { start = 1, finish = 3 }, { start = 5, finish = 7 } },
+      },
+      {
+        msg = "doesn't match with upper case letters",
+        prompt = "ABC def",
+        entry = { index = 3, ordinal = "ABC def ghi" },
+        expected_score = -1,
+        expected_highlights = { { start = 5, finish = 7 } },
+      },
+    } do
+      with_smartcase(false, case)
+    end
+  end)
+
+  describe("when smartcase=OFF", function()
+    for _, case in ipairs {
+      {
+        msg = "doesn't match",
+        prompt = "abc def",
+        entry = { index = 3, ordinal = "abc d" },
+        expected_score = -1,
+        expected_highlights = { { start = 1, finish = 3 } },
+      },
+      {
+        msg = "matches with lower case letters only",
+        prompt = "abc def",
+        entry = { index = 3, ordinal = "abc def ghi" },
+        expected_score = 3,
+        expected_highlights = { { start = 1, finish = 3 }, { start = 5, finish = 7 } },
+      },
+      {
+        msg = "matches with upper case letters",
+        prompt = "ABC def",
+        entry = { index = 3, ordinal = "ABC def ghi" },
+        expected_score = 3,
+        expected_highlights = { { start = 1, finish = 3 }, { start = 5, finish = 7 } },
+      },
+    } do
+      with_smartcase(true, case)
+    end
+  end)
+end)