chore: Add tests for CodeHandler (#105)

* chore: Extract test utils to separate file

This makes it possible to reuse the utils in other test files.

* chore: Add tests for CodeHandler

test/CodeHandlerTest.cpp

@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2025 Povilas Kanapickas
+ *
+ * This file is part of QodeAssist.
+ *
+ * QodeAssist is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * QodeAssist is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with QodeAssist. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "CodeHandler.hpp"
+#include "TestUtils.hpp"
+
+#include <gtest/gtest.h>
+#include <QObject>
+#include <QString>
+
+using namespace QodeAssist;
+
+class CodeHandlerTest : public QObject, public testing::Test
+{
+    // Tests are written in the fixture format with the expectation that CodeHandler will
+    // be expanded.
+    Q_OBJECT
+};
+
+TEST_F(CodeHandlerTest, testProcessTextWithCodeBlock)
+{
+    QString input = "This is a comment\n"
+                    "```python\nprint('Hello, world!')\n```\n"
+                    "Another comment";
+
+    EXPECT_EQ(
+        CodeHandler::processText(input),
+        "# This is a comment\n\nprint('Hello, world!')\n# Another comment\n\n");
+}
+
+TEST_F(CodeHandlerTest, testProcessTextWithMultipleCodeBlocks)
+{
+    QString input = "First comment\n```python\nprint('Block 1')\n"
+                    "```\nMiddle comment\n"
+                    "```cpp\ncout << \"Block 2\";\n```\n"
+                    "Last comment";
+
+    EXPECT_EQ(
+        CodeHandler::processText(input),
+        "# First comment\n\n"
+        "print('Block 1')\n"
+        "// Middle comment\n\n"
+        "cout << \"Block 2\";\n"
+        "// Last comment\n\n");
+}
+
+TEST_F(CodeHandlerTest, testProcessTextWithEmptyLines)
+{
+    QString input = "Comment with empty line\n\n```python\nprint('Hello')\n```\n\nAnother comment";
+
+    EXPECT_EQ(
+        CodeHandler::processText(input),
+        "# Comment with empty line\n\n\nprint('Hello')\n\n# Another comment\n\n");
+}
+
+TEST_F(CodeHandlerTest, testProcessTextWithoutCodeBlock)
+{
+    QString input = "This is just a comment\nwith multiple lines";
+
+    EXPECT_EQ(
+        CodeHandler::processText(input), "// This is just a comment\n// with multiple lines\n\n");
+}
+
+TEST_F(CodeHandlerTest, testProcessTextWithDifferentLanguages)
+{
+    QString input = "Python code:\n"
+                    "```python\nprint('Hello')\n```\n"
+                    "JavaScript code:\n"
+                    "```javascript\nconsole.log('Hello');\n```";
+
+    EXPECT_EQ(
+        CodeHandler::processText(input),
+        "# Python code:\n\nprint('Hello')\n"
+        "// JavaScript code:\n\nconsole.log('Hello');\n");
+}
+
+TEST_F(CodeHandlerTest, testDetectLanguage)
+{
+    EXPECT_EQ(CodeHandler::detectLanguage("```python"), "python");
+    EXPECT_EQ(CodeHandler::detectLanguage("```javascript"), "javascript");
+    EXPECT_EQ(CodeHandler::detectLanguage("```cpp"), "cpp");
+    EXPECT_EQ(CodeHandler::detectLanguage("``` ruby "), "ruby");
+    EXPECT_EQ(CodeHandler::detectLanguage("```"), "");
+    EXPECT_EQ(CodeHandler::detectLanguage("``` "), "");
+}
+TEST_F(CodeHandlerTest, testCommentPrefixForDifferentLanguages)
+{
+    struct TestCase
+    {
+        std::string language;
+        QString input;
+        QString expected;
+    };
+
+    std::vector<TestCase> testCases
+        = {{"python", "Comment\n```python\ncode\n```", "# Comment\n\ncode\n"},
+           {"cpp", "Comment\n```cpp\ncode\n```", "// Comment\n\ncode\n"},
+           {"ruby", "Comment\n```ruby\ncode\n```", "# Comment\n\ncode\n"},
+           {"lua", "Comment\n```lua\ncode\n```", "-- Comment\n\ncode\n"}};
+
+    for (const auto &testCase : testCases) {
+        EXPECT_EQ(CodeHandler::processText(testCase.input), testCase.expected)
+            << "Failed for language: " << testCase.language;
+    }
+}
+
+TEST_F(CodeHandlerTest, testEmptyInput)
+{
+    EXPECT_EQ(CodeHandler::processText(""), "\n\n");
+}
+
+TEST_F(CodeHandlerTest, testCodeBlockWithoutLanguage)
+{
+    QString input = "Comment\n```\ncode\n```";
+
+    EXPECT_EQ(CodeHandler::processText(input), "// Comment\n\ncode\n");
+}
+
+#include "CodeHandlerTest.moc"