test: expand coverage across readers, writers, cmd, ui, diff and merge

Implements tests/_plans and previously deferred packages; updates plan
README with new coverage numbers.

pkg/writers/template/funcmap_test.go

@@ -0,0 +1,75 @@
+package template
+
+import (
+	"bytes"
+	"reflect"
+	"testing"
+	"text/template"
+)
+
+func TestBuildFuncMapEntriesAreFunctions(t *testing.T) {
+	fm := BuildFuncMap()
+	if len(fm) < 100 {
+		t.Errorf("unexpectedly small func map: %d", len(fm))
+	}
+	for name, fn := range fm {
+		if reflect.TypeOf(fn).Kind() != reflect.Func {
+			t.Errorf("%s is not a function", name)
+		}
+	}
+	for _, name := range []string{"toSnakeCase", "sqlToGo", "filterTables", "toJSON", "enumerate", "get", "sortTablesByName", "dict", "seq"} {
+		if _, ok := fm[name]; !ok {
+			t.Errorf("missing %s", name)
+		}
+	}
+	// Must be accepted by text/template (valid names and signatures).
+	if _, err := template.New("x").Funcs(fm).Parse("ok"); err != nil {
+		t.Fatalf("funcmap rejected by text/template: %v", err)
+	}
+}
+
+func TestBuildFuncMapRender(t *testing.T) {
+	tests := []struct {
+		name, tmpl, want string
+	}{
+		{"add", `{{add 2 3}}`, "5"},
+		{"sub", `{{sub 5 3}}`, "2"},
+		{"mul", `{{mul 2 3}}`, "6"},
+		{"div", `{{div 6 3}}`, "2"},
+		{"div zero", `{{div 6 0}}`, "0"},
+		{"mod", `{{mod 7 3}}`, "1"},
+		{"mod zero", `{{mod 7 0}}`, "0"},
+		{"default nil", `{{default "d" .Missing}}`, "d"},
+		{"default set", `{{default "d" "v"}}`, "v"},
+		{"dict", `{{get (dict "a" 1) "a"}}`, "1"},
+		{"dict odd", `{{if dict "a"}}set{{else}}nil{{end}}`, "nil"},
+		{"dict non-string key", `{{if dict 1 2}}set{{else}}nil{{end}}`, "nil"},
+		{"list", `{{len (list 1 2 3)}}`, "3"},
+		{"seq", `{{range seq 1 3}}{{.}}{{end}}`, "123"},
+		{"seq reversed", `{{len (seq 3 1)}}`, "0"},
+		{"snake", `{{toSnakeCase "UserName"}}`, "user_name"},
+		{"pluralize", `{{pluralize "category"}}`, "categories"},
+		{"sqlToGo", `{{sqlToGo "integer" true}}`, ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tpl, err := template.New("t").Funcs(BuildFuncMap()).Parse(tt.tmpl)
+			if err != nil {
+				t.Fatalf("parse: %v", err)
+			}
+			var buf bytes.Buffer
+			if err := tpl.Execute(&buf, map[string]interface{}{}); err != nil {
+				t.Fatalf("execute: %v", err)
+			}
+			if tt.name == "sqlToGo" {
+				if buf.Len() == 0 {
+					t.Error("sqlToGo rendered nothing")
+				}
+				return
+			}
+			if buf.String() != tt.want {
+				t.Errorf("got %q, want %q", buf.String(), tt.want)
+			}
+		})
+	}
+}