Add config validation

.runny.yaml

@@ -47,8 +47,3 @@ commands:
     needs:
       - demo-broken
     run: ls
-
-  demo-unknown-dependency:
-    needs:
-      - unknown
-    run: ls

go.mod

@@ -12,6 +12,7 @@ require (
 require (
 	github.com/bahlo/generic-list-go v0.2.0 // indirect
 	github.com/buger/jsonparser v1.1.1 // indirect
+	github.com/dominikbraun/graph v0.23.0 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect

go.sum

@@ -4,6 +4,8 @@ github.com/buger/jsonparser v1.1.1 h1:2PnMjfWD7wBILjqQbt530v576A/cAbQvEW9gGIpYMU
 github.com/buger/jsonparser v1.1.1/go.mod h1:6RYKKt7H4d4+iWqouImQ9R2FZql3VbhNgx27UK13J/0=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dominikbraun/graph v0.23.0 h1:TdZB4pPqCLFxYhdyMFb1TBdFxp8XLcJfTTBQucVPgCo=
+github.com/dominikbraun/graph v0.23.0/go.mod h1:yOjYyogZLY1LSG9E33JWZJiq5k83Qy2C6POAuiViluc=
 github.com/fatih/color v1.17.0 h1:GlRw1BRJxkpqUCBKzKOw098ed57fEsKeNjpTe3cSjK4=
 github.com/fatih/color v1.17.0/go.mod h1:YZ7TlrGPkiz6ku9fK3TLD/pl3CpsiFyu8N92HLgmosI=
 github.com/invopop/jsonschema v0.12.0 h1:6ovsNSuvn9wEQVOyc72aycBMVQFKz7cPdMJn10CvzRI=

runny/fixtures/invalid-circular-dependency.yaml

@@ -0,0 +1,7 @@
+commands:
+  foo:
+    needs:
+      - bar
+  bar:
+    needs:
+      - foo

runny/utils.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"strings"
 
+	"github.com/dominikbraun/graph"
 	"gopkg.in/yaml.v3"
 )
 
@@ -37,5 +38,30 @@ func readConfig(path string) (Config, error) {
 		}
 		return conf, err
 	}
-	return conf, nil
+
+	return conf, conf.validate()
+}
+
+func (c *Config) validate() error {
+	hash := func(c CommandName) string {
+		return string(c)
+	}
+	g := graph.New(hash, graph.Directed(), graph.PreventCycles())
+
+	for cmdName := range c.Commands {
+		err := g.AddVertex(cmdName)
+		if err != nil {
+			return fmt.Errorf("error declaring command %s: %v", cmdName, err)
+		}
+	}
+
+	for cmdName, cmd := range c.Commands {
+		for _, needsName := range cmd.Needs {
+			err := g.AddEdge(hash(cmdName), hash(needsName))
+			if err != nil {
+				return fmt.Errorf("error declaring %s as dependency of %s: %v", needsName, cmdName, err)
+			}
+		}
+	}
+	return nil
 }

runny/utils_test.go

@@ -58,3 +58,14 @@ func TestReadInvalidConfig(t *testing.T) {
 		t.Fatalf("unexpected error message: %v", err)
 	}
 }
+
+func TestConfigWithCircularDependency(t *testing.T) {
+	_, err := readConfig("fixtures/invalid-circular-dependency.yaml")
+	if err == nil {
+		t.Fatalf("Expected an error when reading invalid config, but reading was succeeded")
+	}
+
+	if !strings.Contains(err.Error(), "edge would create a cycle") {
+		t.Fatalf("unexpected error message: %v", err)
+	}
+}