flamegraph: add native svg pipeline and tests

1 files changed, 109 insertions, 0 deletions

diff --git a/internal/flamegraph/svgwriter_test.go b/internal/flamegraph/svgwriter_test.go
new file mode 100644
index 0000000..6fdbe3d
--- /dev/null
+++ b/internal/flamegraph/svgwriter_test.go
@@ -0,0 +1,109 @@
+package flamegraph
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func renderSVGForTest(t *testing.T, tr *trie, cfg SVGConfig) string {
+	t.Helper()
+	var buf bytes.Buffer
+	if err := WriteSVG(&buf, tr, cfg); err != nil {
+		t.Fatalf("WriteSVG failed: %v", err)
+	}
+	return buf.String()
+}
+
+func TestWriteSVGBasic(t *testing.T) {
+	tr := newTrie()
+	tr.add([]string{"a", "b"}, 3)
+	tr.add([]string{"a", "c"}, 2)
+	tr.computeTotals()
+
+	svg := renderSVGForTest(t, tr, defaultSVGConfig())
+	if !strings.Contains(svg, "<svg") || !strings.Contains(svg, "</svg>") {
+		t.Fatalf("expected valid svg wrapper, got: %s", svg)
+	}
+	if !strings.Contains(svg, "data-name=\"a\"") || !strings.Contains(svg, "data-name=\"b\"") {
+		t.Fatalf("expected rendered frame names, got: %s", svg)
+	}
+}
+
+func TestWriteSVGEmptyTrie(t *testing.T) {
+	tr := newTrie()
+	tr.computeTotals()
+
+	svg := renderSVGForTest(t, tr, defaultSVGConfig())
+	if !strings.Contains(svg, "<svg") || !strings.Contains(svg, "</svg>") {
+		t.Fatalf("expected valid svg wrapper, got: %s", svg)
+	}
+	if strings.Contains(svg, "class=\"frame\"") {
+		t.Fatalf("expected no rendered frames for empty trie, got: %s", svg)
+	}
+}
+
+func TestWriteSVGMinWidth(t *testing.T) {
+	tr := newTrie()
+	tr.add([]string{"wide"}, 100)
+	tr.add([]string{"tiny"}, 1)
+	tr.computeTotals()
+
+	cfg := defaultSVGConfig()
+	cfg.Width = 120
+	cfg.MinWidthPx = 2.0
+	svg := renderSVGForTest(t, tr, cfg)
+
+	if !strings.Contains(svg, "data-name=\"wide\"") {
+		t.Fatalf("expected wide frame to be rendered, got: %s", svg)
+	}
+	if strings.Contains(svg, "data-name=\"tiny\"") {
+		t.Fatalf("expected tiny frame to be skipped by min width, got: %s", svg)
+	}
+}
+
+func TestWriteSVGTitle(t *testing.T) {
+	tr := newTrie()
+	tr.add([]string{"a"}, 1)
+	tr.computeTotals()
+
+	cfg := defaultSVGConfig()
+	cfg.Title = "Custom Flamegraph"
+	svg := renderSVGForTest(t, tr, cfg)
+
+	if !strings.Contains(svg, "Custom Flamegraph") {
+		t.Fatalf("expected custom title in output, got: %s", svg)
+	}
+}
+
+func TestFrameColor(t *testing.T) {
+	colorA1 := frameColor("read")
+	colorA2 := frameColor("read")
+	colorB := frameColor("write")
+
+	if colorA1 != colorA2 {
+		t.Fatalf("expected deterministic color for identical names, got %q vs %q", colorA1, colorA2)
+	}
+	if !strings.HasPrefix(colorA1, "rgb(") || !strings.HasSuffix(colorA1, ")") {
+		t.Fatalf("expected rgb() format, got %q", colorA1)
+	}
+	if colorA1 == colorB {
+		t.Fatalf("expected different colors for different names, got %q", colorA1)
+	}
+}
+
+func TestWriteSVGInvalidConfigFallsBack(t *testing.T) {
+	tr := newTrie()
+	tr.add([]string{"a"}, 1)
+	tr.computeTotals()
+
+	cfg := SVGConfig{Title: "x", Width: 0, FrameHeight: 0, FontSize: 0, MinWidthPx: 0}
+	svg := renderSVGForTest(t, tr, cfg)
+
+	if !strings.Contains(svg, `width="1200"`) {
+		t.Fatalf("expected fallback width, got: %s", svg)
+	}
+	if !strings.Contains(svg, "I/O Flame Graph") {
+		t.Fatalf("expected fallback title, got: %s", svg)
+	}
+}