Add unit test for parsing build files in bp2build

This involves some minor changes to testing infrastructure.

Bug: 285631638
Fixes: 286545783
Test: unit test
Change-Id: If64ba29308d99e63a1cc5526feaf077f2cb14478

bp2build/build_conversion_test.go

@@ -1946,3 +1946,36 @@ func TestPrettyPrintSelectMapEqualValues(t *testing.T) {
 	actual, _ := prettyPrintAttribute(lla, 0)
 	android.AssertStringEquals(t, "Print the common value if all keys in an axis have the same value", `[":libfoo.impl"]`, actual)
 }
+
+func TestAlreadyPresentBuildTarget(t *testing.T) {
+	bp := `
+	custom {
+		name: "foo",
+	}
+	custom {
+		name: "bar",
+	}
+	`
+	alreadyPresentBuildFile :=
+		MakeBazelTarget(
+			"custom",
+			"foo",
+			AttrNameToString{},
+		)
+	expectedBazelTargets := []string{
+		MakeBazelTarget(
+			"custom",
+			"bar",
+			AttrNameToString{},
+		),
+	}
+	registerCustomModule := func(ctx android.RegistrationContext) {
+		ctx.RegisterModuleType("custom", customModuleFactoryHostAndDevice)
+	}
+	RunBp2BuildTestCase(t, registerCustomModule, Bp2buildTestCase{
+		AlreadyExistingBuildContents: alreadyPresentBuildFile,
+		Blueprint:                    bp,
+		ExpectedBazelTargets:         expectedBazelTargets,
+		Description:                  "Not duplicating work for an already-present BUILD target.",
+	})
+}