1 files changed, 76 insertions, 0 deletions
diff --git a/internal/passgen/passgen_test.go b/internal/passgen/passgen_test.go
new file mode 100644
index 0000000..8c70420
--- /dev/null
+++ b/internal/passgen/passgen_test.go
@@ -0,0 +1,76 @@
+package passgen
+
+import (
+	"bytes"
+	"io"
+	"strings"
+	"testing"
+)
+
+func TestGenerateUsesRequestedLengthAndAlphabet(t *testing.T) {
+	opts := Options{
+		Length:    64,
+		UseLower:  true,
+		UseUpper:  false,
+		UseDigits: false,
+	}
+
+	password, err := Generate(opts)
+	if err != nil {
+		t.Fatalf("Generate returned error: %v", err)
+	}
+
+	if len(password) != opts.Length {
+		t.Fatalf("password length = %d, want %d", len(password), opts.Length)
+	}
+
+	for _, ch := range password {
+		if !strings.ContainsRune(lowerChars, ch) {
+			t.Fatalf("password contains character outside requested alphabet: %q", ch)
+		}
+	}
+}
+
+func TestGenerateRejectsEmptyAlphabet(t *testing.T) {
+	_, err := Generate(Options{Length: 24})
+	if err != ErrEmptyAlphabet {
+		t.Fatalf("Generate error = %v, want %v", err, ErrEmptyAlphabet)
+	}
+}
+
+func TestGenerateUsesProvidedRandomReader(t *testing.T) {
+	opts := Options{
+		Length:     3,
+		UseLower:   true,
+		UseUpper:   false,
+		UseDigits:  false,
+		UseSymbols: false,
+		Random:     bytes.NewReader([]byte{0, 1, 2}),
+	}
+
+	password, err := Generate(opts)
+	if err != nil {
+		t.Fatalf("Generate returned error: %v", err)
+	}
+
+	if password != "abc" {
+		t.Fatalf("password = %q, want %q", password, "abc")
+	}
+}
+
+func TestGenerateReturnsRandomReaderError(t *testing.T) {
+	opts := Options{
+		Length:     1,
+		UseLower:   true,
+		UseUpper:   false,
+		UseDigits:  false,
+		UseSymbols: false,
+		Random:     strings.NewReader(""),
+	}
+
+	if _, err := Generate(opts); err == nil {
+		t.Fatalf("Generate returned nil error")
+	} else if !strings.Contains(err.Error(), io.EOF.Error()) {
+		t.Fatalf("Generate error = %v, want EOF context", err)
+	}
+}