Implement Equal on postgres.ParameterSet

Equal is one of the few expectations we can use in our test suite.

Author: cbandy

internal/postgres/parameters.go

@@ -106,6 +106,17 @@ func (ps *ParameterSet) DeepCopy() *ParameterSet {
 	}
 }
 
+func (ps *ParameterSet) Equal(other *ParameterSet) bool {
+	if ps == nil && other == nil {
+		return true
+	}
+	if ps == nil || other == nil {
+		return false
+	}
+
+	return maps.Equal(ps.values, other.values)
+}
+
 // Add sets parameter name to value.
 func (ps *ParameterSet) Add(name, value string) {
 	ps.values[ps.normalize(name)] = value

internal/postgres/parameters_test.go

@@ -97,3 +97,43 @@ func TestParameterSetAppendToList(t *testing.T) {
 	ps.AppendToList("full", "a", "cd", `"e"`)
 	assert.Equal(t, ps.Value("full"), `a,b,a,cd,"e"`)
 }
+
+func TestParameterSetEqual(t *testing.T) {
+	var Nil *ParameterSet
+	ps1 := NewParameterSet()
+	ps2 := NewParameterSet()
+
+	// nil equals nil, and empty does not equal nil
+	assert.Assert(t, Nil.Equal(nil))
+	assert.Assert(t, !Nil.Equal(ps1))
+	assert.Assert(t, !ps1.Equal(nil))
+
+	// empty equals empty
+	assert.Assert(t, ps1.Equal(ps2))
+	assert.Assert(t, ps2.Equal(ps1))
+
+	// different keys are not equal
+	ps1.Add("a", "b")
+	assert.Assert(t, !ps1.Equal(nil))
+	assert.Assert(t, !Nil.Equal(ps1))
+	assert.Assert(t, !ps1.Equal(ps2))
+	assert.Assert(t, !ps2.Equal(ps1))
+
+	// different values are not equal
+	ps2.Add("a", "c")
+	assert.Assert(t, !ps1.Equal(ps2))
+	assert.Assert(t, !ps2.Equal(ps1))
+
+	// normalized keys+values are equal
+	ps1.Add("A", "c")
+	assert.Assert(t, ps1.Equal(ps2))
+	assert.Assert(t, ps2.Equal(ps1))
+
+	// [assert.DeepEqual] can only compare exported fields.
+	// When present, the `(T) Equal(T) bool` method is used instead.
+	//
+	// https://pkg.go.dev/github.com/google/go-cmp/cmp#Equal
+	t.Run("DeepEqual", func(t *testing.T) {
+		assert.DeepEqual(t, NewParameterSet(), NewParameterSet())
+	})
+}