1 files changed, 83 insertions, 0 deletions
diff --git a/internal/render/render_test.go b/internal/render/render_test.go
index d06fc7b..4879855 100644
--- a/internal/render/render_test.go
+++ b/internal/render/render_test.go
@@ -403,3 +403,86 @@ func TestNoSpeciesIsPrivileged(t *testing.T) {
 		t.Errorf("grass at zero must be dropped like any other species:\n%s", out)
 	}
 }
+
+// A narrow range cannot be labelled in whole degrees: rounding makes adjacent
+// rows read the same, so the axis claims two different temperatures are equal.
+func TestNarrowRangeGetsDecimalAxisLabels(t *testing.T) {
+	cfg := testConfig()
+	cfg.Graph = true
+	var rows []openmeteo.Row
+	for i, temp := range []float64{15.7, 16.0, 16.0, 15.2, 14.8, 15.1, 15.2, 15.2} {
+		r := row(0, temp, 3, 0, 0)
+		r.When = time.Date(2026, 8, 25, 15+i, 0, 0, 0, time.UTC)
+		rows = append(rows, r)
+	}
+	out := Render(view(rows...), cfg, 80, false)
+
+	var labels []string
+	for _, l := range strings.Split(out, "\n") {
+		if i := strings.Index(l, "│"); i > 0 {
+			if lbl := strings.TrimSpace(l[:i]); lbl != "" && lbl != "rain" {
+				labels = append(labels, lbl)
+			}
+		}
+	}
+	if len(labels) < 3 {
+		t.Fatalf("expected three axis labels, got %v\n%s", labels, out)
+	}
+	seen := map[string]bool{}
+	for _, l := range labels {
+		if seen[l] {
+			t.Errorf("axis label %q repeats; a 1.2 degree span needs decimals:\n%s", l, out)
+		}
+		seen[l] = true
+		if !strings.Contains(l, ".") {
+			t.Errorf("label %q should carry a decimal for a narrow range", l)
+		}
+	}
+}
+
+// A wide range stays in whole degrees: decimals there are noise.
+func TestWideRangeKeepsWholeDegreeLabels(t *testing.T) {
+	cfg := testConfig()
+	cfg.Graph = true
+	var rows []openmeteo.Row
+	for i, temp := range []float64{5, 12, 18, 24, 28, 22, 14, 7} {
+		r := row(0, temp, 3, 0, 0)
+		r.When = time.Date(2026, 8, 25, 15+i, 0, 0, 0, time.UTC)
+		rows = append(rows, r)
+	}
+	out := Render(view(rows...), cfg, 80, false)
+	for _, l := range strings.Split(out, "\n") {
+		if i := strings.Index(l, "│"); i > 0 {
+			lbl := strings.TrimSpace(l[:i])
+			if strings.Contains(lbl, ".") {
+				t.Errorf("wide range should use whole degrees, got %q", lbl)
+			}
+		}
+	}
+}
+
+func TestAxisLabelPrecisionAndWidth(t *testing.T) {
+	cases := []struct {
+		lo, hi   float64
+		maxWidth int
+		wantDot  bool
+		why      string
+	}{
+		{14.8, 16.0, 5, true, "1.2 degrees needs decimals"},
+		{12, 28, 5, false, "16 degrees does not"},
+		{15, 17, 5, false, "exactly the threshold stays whole"},
+		{-20.4, -19.6, 5, false, "decimals would not fit, so fall back"},
+	}
+	for _, c := range cases {
+		f := tempLabeller(c.lo, c.hi, c.maxWidth)
+		got := f(c.lo)
+		if strings.Contains(got, ".") != c.wantDot {
+			t.Errorf("lo=%v hi=%v gave %q; %s", c.lo, c.hi, got, c.why)
+		}
+		for _, v := range []float64{c.lo, c.hi} {
+			if w := DisplayWidth(f(v)); w > c.maxWidth {
+				t.Errorf("label %q is %d cells, over the %d-cell gutter", f(v), w, c.maxWidth)
+			}
+		}
+	}
+}