Add ability to create a clio.Application that runs test assertions in…

…stead of cmd.RunE (#37)

In order to test the configuration setup (arg, config file, and env var parsing) in
clio applications, add a cliotestutils package that spies on the config that would be
created before calling the command's RunE instead of just wrapping it as a normal
clio.Application does. This enables consumers of the library to write unit tests that, for example, assert
that a given command accepts a given flag.

---------

Signed-off-by: Alex Goodman <[email protected]>
Signed-off-by: Will Murphy <[email protected]>
Co-authored-by: Alex Goodman <[email protected]>

cliotestutils/application.go

@@ -0,0 +1,73 @@
+package cliotestutils
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/spf13/cobra"
+	"github.com/stretchr/testify/assert"
+
+	"github.com/anchore/clio"
+)
+
+// NewApplication takes a testing.T, a clio setup config, and a slice of assertions, and returns
+// a clio application that will, instead of setting up commands with their normal RunE, set up commands
+// such that the assertions are called with the testing.T after config state is set up by reading flags,
+// env vars, and config files. Useful for testing that expected configuration options are wired up.
+// Note that initializers will be cleared from the clio setup config, since the initialization may happen
+// more than once and affect global state. For necessary global state, a workaround is to set it in a TestingMain.
+func NewApplication(t *testing.T, cfg *clio.SetupConfig, assertions ...AssertionFunc) clio.Application {
+	cfg.Initializers = nil
+	a := clio.New(*cfg)
+
+	var asserter assertionClosure = func(cmd *cobra.Command, args []string, cfgs ...any) {
+		for _, assertion := range assertions {
+			assertion(t, cmd, args, cfgs...)
+		}
+	}
+
+	return &testApplication{
+		a,
+		asserter,
+	}
+}
+
+type AssertionFunc func(t *testing.T, cmd *cobra.Command, args []string, cfgs ...any)
+
+func OptionsEquals(wantOpts any) AssertionFunc {
+	return func(t *testing.T, cmd *cobra.Command, args []string, cfgs ...any) {
+		assert.Equal(t, len(cfgs), 1)
+		if d := cmp.Diff(wantOpts, cfgs[0]); d != "" {
+			t.Errorf("mismatched options (-want +got):\n%s", d)
+		}
+	}
+}
+
+type assertionClosure func(cmd *cobra.Command, args []string, cfgs ...any)
+
+type testApplication struct {
+	clio.Application
+	assertion assertionClosure
+}
+
+func (a *testApplication) SetupCommand(cmd *cobra.Command, cfgs ...any) *cobra.Command {
+	cmd.RunE = func(cmd *cobra.Command, args []string) error {
+		a.assertion(cmd, args, cfgs...)
+		return nil
+	}
+	return a.Application.SetupCommand(cmd, cfgs...)
+}
+
+func (a *testApplication) SetupRootCommand(cmd *cobra.Command, cfgs ...any) *cobra.Command {
+	cmd.RunE = func(cmd *cobra.Command, args []string) error {
+		a.assertion(cmd, args, cfgs...)
+		return nil
+	}
+	return a.Application.SetupRootCommand(cmd, cfgs...)
+}
+
+/*
+// TODO: WISHLIST:
+1. Helper to wire up a test fixture as the only config file that will be found
+2. Set env vars by passing map[string]string (currently possible by caller in test; a helper here would be nice.)
+*/

go.mod

@@ -5,6 +5,7 @@ go 1.18
 require (
 	github.com/anchore/fangs v0.0.0-20230807173929-13c94c86f47e
 	github.com/anchore/go-logger v0.0.0-20230725134548-c21dafa1ec5a
+	github.com/google/go-cmp v0.5.9
 	github.com/gookit/color v1.5.4
 	github.com/iancoleman/strcase v0.3.0
 	github.com/pborman/indent v1.2.1

go.sum

@@ -109,6 +109,7 @@ github.com/google/go-cmp v0.5.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
+github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/martian v2.1.0+incompatible/go.mod h1:9I4somxYTbIHy5NJKHRl3wXiIaQGbYVAs8BPL6v8lEs=
 github.com/google/martian/v3 v3.0.0/go.mod h1:y5Zk1BBys9G+gd6Jrk0W3cC1+ELVxBWuIGO+w/tUAp0=
 github.com/google/martian/v3 v3.1.0/go.mod h1:y5Zk1BBys9G+gd6Jrk0W3cC1+ELVxBWuIGO+w/tUAp0=