Add comprehensive unit tests for services and main package

- Implement tests for the app service, including course processing from file and URI.
- Create mock implementations for CourseParser and Exporter to facilitate testing.
- Add tests for HTML cleaner service to validate HTML content cleaning functionality.
- Develop tests for the parser service, covering course fetching and loading from files.
- Introduce tests for utility functions in the main package, ensuring URI validation and string joining.
- Include benchmarks for performance evaluation of key functions.

main_test.go

@@ -0,0 +1,175 @@
+// Package main_test provides tests for the main package utility functions.
+package main
+
+import (
+	"testing"
+)
+
+// TestIsURI tests the isURI function with various input scenarios.
+func TestIsURI(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected bool
+	}{
+		{
+			name:     "valid HTTP URI",
+			input:    "http://example.com",
+			expected: true,
+		},
+		{
+			name:     "valid HTTPS URI",
+			input:    "https://example.com",
+			expected: true,
+		},
+		{
+			name:     "valid Articulate Rise URI",
+			input:    "https://rise.articulate.com/share/N_APNg40Vr2CSH2xNz-ZLATM5kNviDIO#/",
+			expected: true,
+		},
+		{
+			name:     "local file path",
+			input:    "C:\\Users\\test\\file.json",
+			expected: false,
+		},
+		{
+			name:     "relative file path",
+			input:    "./sample.json",
+			expected: false,
+		},
+		{
+			name:     "filename only",
+			input:    "sample.json",
+			expected: false,
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			expected: false,
+		},
+		{
+			name:     "short string",
+			input:    "http",
+			expected: false,
+		},
+		{
+			name:     "malformed URI",
+			input:    "htp://example.com",
+			expected: false,
+		},
+		{
+			name:     "FTP URI",
+			input:    "ftp://example.com",
+			expected: false,
+		},
+		{
+			name:     "HTTP with extra characters",
+			input:    "xhttp://example.com",
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := isURI(tt.input)
+			if result != tt.expected {
+				t.Errorf("isURI(%q) = %v, want %v", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+// TestJoinStrings tests the joinStrings function with various input scenarios.
+func TestJoinStrings(t *testing.T) {
+	tests := []struct {
+		name      string
+		strs      []string
+		separator string
+		expected  string
+	}{
+		{
+			name:      "empty slice",
+			strs:      []string{},
+			separator: ", ",
+			expected:  "",
+		},
+		{
+			name:      "single string",
+			strs:      []string{"hello"},
+			separator: ", ",
+			expected:  "hello",
+		},
+		{
+			name:      "two strings with comma separator",
+			strs:      []string{"markdown", "docx"},
+			separator: ", ",
+			expected:  "markdown, docx",
+		},
+		{
+			name:      "three strings with comma separator",
+			strs:      []string{"markdown", "md", "docx"},
+			separator: ", ",
+			expected:  "markdown, md, docx",
+		},
+		{
+			name:      "multiple strings with pipe separator",
+			strs:      []string{"option1", "option2", "option3"},
+			separator: " | ",
+			expected:  "option1 | option2 | option3",
+		},
+		{
+			name:      "strings with no separator",
+			strs:      []string{"a", "b", "c"},
+			separator: "",
+			expected:  "abc",
+		},
+		{
+			name:      "strings with newline separator",
+			strs:      []string{"line1", "line2", "line3"},
+			separator: "\n",
+			expected:  "line1\nline2\nline3",
+		},
+		{
+			name:      "empty strings in slice",
+			strs:      []string{"", "middle", ""},
+			separator: "-",
+			expected:  "-middle-",
+		},
+		{
+			name:      "nil slice",
+			strs:      nil,
+			separator: ", ",
+			expected:  "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := joinStrings(tt.strs, tt.separator)
+			if result != tt.expected {
+				t.Errorf("joinStrings(%v, %q) = %q, want %q", tt.strs, tt.separator, result, tt.expected)
+			}
+		})
+	}
+}
+
+// BenchmarkIsURI benchmarks the isURI function performance.
+func BenchmarkIsURI(b *testing.B) {
+	testStr := "https://rise.articulate.com/share/N_APNg40Vr2CSH2xNz-ZLATM5kNviDIO#/"
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		isURI(testStr)
+	}
+}
+
+// BenchmarkJoinStrings benchmarks the joinStrings function performance.
+func BenchmarkJoinStrings(b *testing.B) {
+	strs := []string{"markdown", "md", "docx", "word", "pdf", "html"}
+	separator := ", "
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		joinStrings(strs, separator)
+	}
+}