tests: add util tests

internal/utils/string_utils_test.go

@@ -0,0 +1,50 @@
+package utils_test
+
+import (
+	"testing"
+	"tinyauth/internal/utils"
+
+	"gotest.tools/v3/assert"
+)
+
+func TestCapitalize(t *testing.T) {
+	// Test empty string
+	assert.Equal(t, "", utils.Capitalize(""))
+
+	// Test single character
+	assert.Equal(t, "A", utils.Capitalize("a"))
+
+	// Test multiple characters
+	assert.Equal(t, "Hello", utils.Capitalize("hello"))
+
+	// Test already capitalized
+	assert.Equal(t, "World", utils.Capitalize("World"))
+
+	// Test non-alphabetic first character
+	assert.Equal(t, "1number", utils.Capitalize("1number"))
+
+	// Test Unicode characters
+	assert.Equal(t, "Γειά", utils.Capitalize("γειά"))
+	assert.Equal(t, "Привет", utils.Capitalize("привет"))
+
+}
+
+func TestCoalesceToString(t *testing.T) {
+	// Test with []any containing strings
+	assert.Equal(t, "a,b,c", utils.CoalesceToString([]any{"a", "b", "c"}))
+
+	// Test with []any containing mixed types
+	assert.Equal(t, "a,c", utils.CoalesceToString([]any{"a", 1, "c", true}))
+
+	// Test with []any containing no strings
+	assert.Equal(t, "", utils.CoalesceToString([]any{1, 2, 3}))
+
+	// Test with string input
+	assert.Equal(t, "hello", utils.CoalesceToString("hello"))
+
+	// Test with non-string, non-[]any input
+	assert.Equal(t, "", utils.CoalesceToString(123))
+
+	// Test with nil input
+	assert.Equal(t, "", utils.CoalesceToString(nil))
+}