1 files changed, 123 insertions, 0 deletions
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index 06c0234..46a8635 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -156,3 +156,126 @@ func TestWriteDefaultRoundTrips(t *testing.T) {
 		t.Fatalf("the file we generate must validate: %v", err)
 	}
 }
+
+func TestCustomColumnDeclaration(t *testing.T) {
+	cfg, err := Load(write(t, `columns=hour,temp,birch
+column.birch = air:birch_pollen
+label.birch = brzoza
+width.birch = 7
+decimals.birch = 2
+suffix.birch = g
+`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	cc, ok := cfg.Custom["birch"]
+	if !ok {
+		t.Fatal("birch was not declared")
+	}
+	if cc.Source != "air" || cc.Field != "birch_pollen" {
+		t.Errorf("source/field = %q/%q", cc.Source, cc.Field)
+	}
+	if cc.Label != "brzoza" || cc.Width != 7 || cc.Decimals != 2 || cc.Suffix != "g" {
+		t.Errorf("attributes not parsed: %+v", cc)
+	}
+	if err := cfg.Validate(); err != nil {
+		t.Fatalf("a complete declaration must validate: %v", err)
+	}
+}
+
+// Only the fields a selected column needs, split by which API serves them.
+func TestCustomColumnsSplitFieldsByApi(t *testing.T) {
+	cfg, err := Load(write(t, `columns=hour,temp,birch,soil
+column.birch = air:birch_pollen
+column.soil = forecast:soil_temperature_0cm
+`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	fc := strings.Join(cfg.Fields(), ",")
+	if !strings.Contains(fc, "soil_temperature_0cm") || !strings.Contains(fc, "temperature_2m") {
+		t.Errorf("forecast fields = %q", fc)
+	}
+	if strings.Contains(fc, "birch_pollen") {
+		t.Errorf("an air field must not be asked of the forecast API: %q", fc)
+	}
+	if air := strings.Join(cfg.AirFields(), ","); air != "birch_pollen" {
+		t.Errorf("air fields = %q, want birch_pollen", air)
+	}
+}
+
+// No custom air column means no second request at all.
+func TestNoAirFieldsWhenNoneDeclared(t *testing.T) {
+	if got := Default().AirFields(); len(got) != 0 {
+		t.Fatalf("AirFields() = %v, want empty", got)
+	}
+}
+
+func TestCustomColumnErrors(t *testing.T) {
+	for name, body := range map[string]string{
+		"no source":      "column.x = birch_pollen\ncolumns=hour,x\n",
+		"unknown source": "column.x = weather:birch_pollen\ncolumns=hour,x\n",
+		"empty field":    "column.x = air:\ncolumns=hour,x\n",
+		"bad width":      "column.x = air:f\nwidth.x = wide\n",
+		"bad decimals":   "column.x = air:f\ndecimals.x = 9\n",
+	} {
+		t.Run(name, func(t *testing.T) {
+			if _, err := Load(write(t, body)); err == nil {
+				t.Fatalf("expected an error for %q", body)
+			}
+		})
+	}
+}
+
+// Attributes without a declaration are a typo, not a silent no-op.
+func TestAttributesWithoutDeclarationAreRejected(t *testing.T) {
+	cfg, err := Load(write(t, "label.birch = brzoza\n"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := cfg.Validate(); err == nil {
+		t.Fatal("label.birch without column.birch must be an error")
+	}
+}
+
+// Shadowing a built-in would make which column you get depend on lookup order.
+func TestCustomColumnCannotShadowABuiltIn(t *testing.T) {
+	cfg, err := Load(write(t, "column.temp = air:birch_pollen\n"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = cfg.Validate()
+	if err == nil || !strings.Contains(err.Error(), "built-in") {
+		t.Fatalf("expected a built-in clash error, got %v", err)
+	}
+}
+
+// An undeclared column name should say how to declare it.
+func TestUnknownColumnSuggestsDeclaringIt(t *testing.T) {
+	cfg := Default()
+	cfg.Columns = []string{"hour", "birch"}
+	err := cfg.Validate()
+	if err == nil || !strings.Contains(err.Error(), "column.birch") {
+		t.Fatalf("error should show how to declare it, got %v", err)
+	}
+}
+
+func TestPollenExplicitTracksWhoChose(t *testing.T) {
+	cases := map[string]bool{
+		"pollen=grass,birch\n": true,
+		"pollen=all\n":         false,
+		"pollen=none\n":        false,
+	}
+	for body, want := range cases {
+		cfg, err := Load(write(t, body))
+		if err != nil {
+			t.Fatal(err)
+		}
+		if cfg.PollenExplicit != want {
+			t.Errorf("%q gave PollenExplicit=%v, want %v", body, cfg.PollenExplicit, want)
+		}
+	}
+	if Default().PollenExplicit {
+		t.Error("the default is not an explicit choice")
+	}
+}