1 files changed, 99 insertions, 0 deletions
diff --git a/internal/parser/parser_test.go b/internal/parser/parser_test.go
new file mode 100644
index 0000000..05255a5
--- /dev/null
+++ b/internal/parser/parser_test.go
@@ -0,0 +1,99 @@
+package parser
+
+import (
+	"context"
+	"strings"
+	"testing"
+)
+
+func TestParseFile_CSV(t *testing.T) {
+	// We can't easily test file operations without creating temp files
+	// So we'll test the error case
+	ctx := context.Background()
+	_, err := ParseFile(ctx, "/nonexistent/file.csv", "csv")
+
+	if err == nil {
+		t.Error("Expected error for nonexistent file")
+	}
+}
+
+func TestParseWithFormat_CSV(t *testing.T) {
+	ctx := context.Background()
+	input := `test_metric,env=prod,100,1234567890000`
+	reader := strings.NewReader(input)
+
+	samples, err := parseWithFormat(ctx, reader, "csv")
+	if err != nil {
+		t.Fatalf("parseWithFormat(csv) error = %v", err)
+	}
+	if len(samples) != 1 {
+		t.Errorf("Expected 1 sample, got %d", len(samples))
+	}
+}
+
+func TestParseWithFormat_JSON(t *testing.T) {
+	ctx := context.Background()
+	input := `[{"metric": "test_metric", "value": 100, "timestamp_ms": 1234567890000}]`
+	reader := strings.NewReader(input)
+
+	samples, err := parseWithFormat(ctx, reader, "json")
+	if err != nil {
+		t.Fatalf("parseWithFormat(json) error = %v", err)
+	}
+	if len(samples) != 1 {
+		t.Errorf("Expected 1 sample, got %d", len(samples))
+	}
+}
+
+func TestParseWithFormat_UnsupportedFormat(t *testing.T) {
+	ctx := context.Background()
+	reader := strings.NewReader("")
+
+	_, err := parseWithFormat(ctx, reader, "xml")
+	if err == nil {
+		t.Error("Expected error for unsupported format")
+	}
+	if err.Error() != "unsupported format: xml (use csv or json)" {
+		t.Errorf("Unexpected error message: %v", err)
+	}
+}
+
+func TestParseWithFormat_EmptyResult(t *testing.T) {
+	ctx := context.Background()
+	input := `[]` // Empty JSON array
+	reader := strings.NewReader(input)
+
+	_, err := parseWithFormat(ctx, reader, "json")
+	if err == nil {
+		t.Error("Expected error for empty samples")
+	}
+	if err.Error() != "no valid samples found" {
+		t.Errorf("Expected 'no valid samples found' error, got: %v", err)
+	}
+}
+
+func TestParseStdin_Format(t *testing.T) {
+	// We can't easily test stdin without mocking,
+	// but we can verify the error path
+	ctx := context.Background()
+
+	// Test with invalid format
+	_, err := parseWithFormat(ctx, strings.NewReader(""), "invalid_format")
+	if err == nil {
+		t.Error("Expected error for invalid format")
+	}
+}
+
+func TestNewCSVParser(t *testing.T) {
+	parser := NewCSVParser()
+	if parser == nil {
+		t.Error("NewCSVParser() returned nil")
+	}
+}
+
+func TestNewJSONParser(t *testing.T) {
+	parser := NewJSONParser()
+	if parser == nil {
+		t.Error("NewJSONParser() returned nil")
+	}
+}