Fix nil ptr panic when adding env variables to uninitialized Generator

When calling AddProcessEnv on a Generator instance that was created
using zero-value initialization (Generator{}) rather than through
New(), the envMap field would be nil. This caused a panic when
attempting to write to the map in the addEnv helper function.

This commit adds a nil check before writing to the envMap in addEnv. If
the map is uninitialized, it creates a new empty map before proceeding
with the map insertion operation.

A new test case has been added to TestEnvCaching that validates this
scenario by creating a Generator using zero-value initialization and
verifying that AddProcessEnv works correctly without panicking.

Signed-off-by: Andreas Karis <[email protected]>

Author: andreaskaris

generate/generate.go

@@ -540,6 +540,9 @@ func (g *Generator) addEnv(env, key string) {
 	} else {
 		// else the env doesn't exist, so add it and add it's index to g.envMap
 		g.Config.Process.Env = append(g.Config.Process.Env, env)
+		if g.envMap == nil {
+			g.envMap = map[string]int{}
+		}
 		g.envMap[key] = len(g.Config.Process.Env) - 1
 	}
 }

generate/generate_test.go

@@ -124,6 +124,15 @@ func TestEnvCaching(t *testing.T) {
 	}
 	g.AddProcessEnv("", "")
 	assert.Equal(t, []string(nil), g.Config.Process.Env)
+
+	// Test empty ENV with nil envMap.
+	g = generate.Generator{}
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected = []string{"k1=v1"}
+	g.AddProcessEnv("k1", "v1")
+	assert.Equal(t, expected, g.Config.Process.Env)
 }
 
 func TestMultipleEnvCaching(t *testing.T) {